This document discusses multiple sequence alignment. It begins by explaining that pairwise sequence alignment is not reliable for more distantly related sequences, as there may be many possible alignments with the same score. Multiple sequence alignment allows discovering conserved motifs across a protein family. The document then discusses different scoring systems for multiple sequence alignments, including sum-of-pairs and entropy-based scores. It also describes the dynamic programming solution and progressive alignment approaches like CLUSTALW and T-COFFEE. The document concludes by mentioning faster methods like MUSCLE that use hashing to find short matches and build an initial sequence similarity tree.
The document discusses the maximum parsimony method for constructing phylogenetic trees. It states that this method minimizes the number of evolutionary changes needed to explain the differences between sequences. The method prefers the simplest phylogenetic tree that requires the fewest evolutionary changes between ancestral and descendent sequences. It also discusses evaluating different possible trees based on the total number of changes needed across all sequence positions to identify the most parsimonious tree.
This document discusses global and local sequence alignment. It introduces sequence alignment and its uses in identifying similarities between sequences that could indicate functional or evolutionary relationships. It describes the principles of alignment and the different types of alignment, including global alignment, which aligns entire sequences, and local alignment, which matches regions of similarity. Methods for alignment include dot plots, scoring matrices, and dynamic programming. BLAST is introduced as a tool for comparing sequences against databases using local alignment algorithms.
This document provides an outline for a presentation on biological networks, including introducing biological networks, describing their basic components and types, methods for predicting and building networks, sources of interaction data, tools for network visualization and analysis, and a demonstration of building, visualizing and analyzing biological networks using Cytoscape. The presentation covers topics like nodes and edges in networks, features used to analyze networks, methods for predicting networks from sequences and omics data, integrated databases for interaction data, and popular tools for searching, visualizing and performing network analysis.
14th International Conference on Intelligent Systems for Molecular Biology, Software demo, Fortaleza Conference Center, Fortaleza, Brazil, August 6-10, 2006
This document discusses several techniques for analyzing gene expression, including serial analysis of gene expression (SAGE), digital gene expression (DDG), RNA sequencing, SDS-PAGE gel electrophoresis, DNA microarrays, and their applications and limitations. SAGE involves extracting small gene tags that are sequenced to determine expression levels. DDG analyzes EST databases to compare gene proportions between treatments. RNA sequencing directly sequences mRNA fragments to determine expression levels more broadly than microarrays. SDS-PAGE separates proteins by molecular weight. Microarrays detect gene expression by fluorescent hybridization of cDNA to a DNA chip and allow comparison of two conditions.
This document discusses multiple sequence alignment. It begins by explaining that pairwise sequence alignment is not reliable for more distantly related sequences, as there may be many possible alignments with the same score. Multiple sequence alignment allows discovering conserved motifs across a protein family. The document then discusses different scoring systems for multiple sequence alignments, including sum-of-pairs and entropy-based scores. It also describes the dynamic programming solution and progressive alignment approaches like CLUSTALW and T-COFFEE. The document concludes by mentioning faster methods like MUSCLE that use hashing to find short matches and build an initial sequence similarity tree.
The document discusses the maximum parsimony method for constructing phylogenetic trees. It states that this method minimizes the number of evolutionary changes needed to explain the differences between sequences. The method prefers the simplest phylogenetic tree that requires the fewest evolutionary changes between ancestral and descendent sequences. It also discusses evaluating different possible trees based on the total number of changes needed across all sequence positions to identify the most parsimonious tree.
This document discusses global and local sequence alignment. It introduces sequence alignment and its uses in identifying similarities between sequences that could indicate functional or evolutionary relationships. It describes the principles of alignment and the different types of alignment, including global alignment, which aligns entire sequences, and local alignment, which matches regions of similarity. Methods for alignment include dot plots, scoring matrices, and dynamic programming. BLAST is introduced as a tool for comparing sequences against databases using local alignment algorithms.
This document provides an outline for a presentation on biological networks, including introducing biological networks, describing their basic components and types, methods for predicting and building networks, sources of interaction data, tools for network visualization and analysis, and a demonstration of building, visualizing and analyzing biological networks using Cytoscape. The presentation covers topics like nodes and edges in networks, features used to analyze networks, methods for predicting networks from sequences and omics data, integrated databases for interaction data, and popular tools for searching, visualizing and performing network analysis.
14th International Conference on Intelligent Systems for Molecular Biology, Software demo, Fortaleza Conference Center, Fortaleza, Brazil, August 6-10, 2006
This document discusses several techniques for analyzing gene expression, including serial analysis of gene expression (SAGE), digital gene expression (DDG), RNA sequencing, SDS-PAGE gel electrophoresis, DNA microarrays, and their applications and limitations. SAGE involves extracting small gene tags that are sequenced to determine expression levels. DDG analyzes EST databases to compare gene proportions between treatments. RNA sequencing directly sequences mRNA fragments to determine expression levels more broadly than microarrays. SDS-PAGE separates proteins by molecular weight. Microarrays detect gene expression by fluorescent hybridization of cDNA to a DNA chip and allow comparison of two conditions.
This document discusses pathway and network analysis. It defines systems biology and biological networks. Some benefits of studying pathways and networks are that it improves statistical power, allows identification of potential causal mechanisms, and facilitates integration of multiple data types. Types of analysis include gene set enrichment and de novo network construction. Visualization is important for representing relationships between molecules and finding subnetworks. Software like Cytoscape can be used to import networks, map gene expression data to node colors/borders, filter networks, and export publication-quality images. A tutorial demonstrates combining expression and network data in Cytoscape to tell biological stories.
This document reviews protein-protein interactions (PPIs). It discusses how PPIs occur and their importance in biological processes. Several methods are described for identifying PPIs, including yeast two-hybrid systems, co-immunoprecipitation, and computational databases. PPIs help mediate cellular functions and understanding them can provide insight into diseases and new therapeutic approaches.
The Nucleic Acid Database provides structural references and a search engine for DNA and RNA structures. It depicts structures through systematic design based on biological data in tools like the RNA Viewer, Base Pair Viewer, and ATLAS. It also examines structures through innovative methods like the Musical Atlas, which uses musical algorithms to represent DNA structures as instrumental songs.
De novo genome assembly - T.Seemann - IMB winter school 2016 - brisbane, au ...Torsten Seemann
This document discusses de novo genome assembly, which is the process of reconstructing long genomic sequences from many short sequencing reads without the aid of a reference genome. It is challenging due to factors like short read lengths, repetitive sequences that complicate the assembly graph, and sequencing errors. The goals of assembly are to produce contiguous sequences with high completeness and correctness by resolving overlaps between reads into consensus sequences. Metrics like N50, core gene content, and read remapping are used to assess assembly quality.
Slightly modified version of slides on BWA-MEM2 that I presented at IPDPS'19 for the paper: Efficient Architecture-Aware Acceleration of BWA-MEM for Multicore Systems. Vasimuddin Md, Sanchit Misra, Heng Li, Srinivas Aluru. IEEE International Parallel and Distributed Processing Symposium (IPDPS), 2019.
Nadia Pisanti - With the recent New Genome Sequencing Technologies, Medicine and Biology are witnessing a revolution where Computer Science and Data Analysis play a crucial role. In this talk, I will give an overview of perspectives and challenges in this field.
This document discusses biochemical network mapping and visualization. It begins by describing the process of creating a metabolic network graph with nodes representing metabolites and edges representing reactions. While metabolic databases can provide information on known reactions, not all detected metabolites may be present. The document then introduces MetaMapp as an approach to map all detected metabolites into a network graph by combining information on known biochemical reactions with chemical similarity. Cytoscape software allows visualization and analysis of these network graphs. In conclusion, MetaMapp can be used to incorporate all identified metabolites into biochemical modules to aid in interpretation of omics data.
This document discusses metabolic network analysis and summarizes information from the KEGG database. It describes searching metabolic terms on Google and Google Scholar, keywords used in metabolic network analysis, and basic concepts in metabolic network reconstruction. It also provides an overview of the KEGG PATHWAY, MEDICUS, Mapper, and Expression databases and tools for mapping gene expression data onto metabolic pathways. The document concludes by assigning a report task analyzing gene expression data mapped to pathways using KEGG Expression and KegArray.
The biological databases document summarizes several important biological databases including BioGRID, Rfam, miRBase, and ModBase. BioGRID is a curated database of protein-protein and genetic interactions. Rfam contains information about RNA families and annotations for millions of RNA genes. miRBase is an archive of microRNA sequences and annotations that provides a central registry for assigning microRNA names. ModBase is a database of annotated protein structure models calculated in silico that may contain significant errors.
The document summarizes key concepts about gene expression and analysis. It describes the central dogma of biology where DNA is transcribed into RNA which is then translated into protein. Gene structure is explained, noting that eukaryotic genes contain introns and exons. The roles of DNA, RNA and proteins in gene expression are outlined. The processes of transcription, including initiation, elongation and termination are summarized. Post-transcriptional processing of RNA including capping, splicing and polyadenylation is covered. Translation including initiation, elongation and termination is also summarized concisely. Control of gene expression occurs at transcriptional, post-transcriptional, translational and post-translational levels.
The document summarizes a bioinformatics summer camp, including:
1. The camp will cover basic molecular biology and bioinformatics topics like DNA, proteins, gene expression and the genetic code.
2. Students will work on computational analysis projects involving whole genome sequencing, gene expression profiling, and functional and comparative genomics.
3. The camp will teach techniques for analyzing protein structures and interactions, gene expression data, and identifying pockets on protein surfaces.
Mascot is a software package from Matrix Science that interprets mass spectral data into protein identities.
In this presentation we will study about MASCOT and also on how to use it.
The document discusses various methods for structurally aligning proteins, including combinatorial extension, VAST, DALI, SSAP, and TM-align. It also describes Ramachandran plots, which show allowed and favored phi/psi dihedral angle combinations for protein backbone chains based on steric constraints. Structural alignment methods are useful for detecting evolutionary relationships between proteins with low sequence similarity. Ramachandran plots help validate protein structures by identifying conformations not allowed by steric hindrance.
dbSNP is a public archive of genetic polymorphisms including SNPs, insertions/deletions, and repeats. It contains contextual sequence information, frequency data, and experimental methods. dbSNP supports research areas like physical mapping, functional analysis, pharmacogenomics, and evolution. Variations are used as positional markers similar to STSs. Submitted SNPs are assigned IDs and aligned to reference genomes, clustering shared positions into reference SNP clusters. BLAST and FASTA tools allow searching. Null results of invariant sequences are also submitted.
This document discusses protein motifs and domains. It defines a motif as a recurring arrangement of secondary structure found in multiple proteins, such as the HTH, HLH, and hairpin motifs. A domain contains one or more well-characterized motifs and has an independent function. Two common motifs are described: the HTH motif, which contains two antiparallel alpha helices connected by a beta turn for DNA binding; and the HLH motif, which contains two helices connected by a loop, with the larger helix binding DNA and the smaller helix aiding folding. Domains are defined as distinct functional units that are evolutionarily conserved and can exist independently; they are classified based on secondary structure composition.
Structural genomics aims to determine the 3D structures of all proteins encoded by genomes through high-throughput methods. It uses a genome-based approach to solve protein structures rapidly and cost-effectively. Major initiatives like the Protein Structure Initiative have made progress in determining thousands of protein structures. Challenges include expressing membrane and eukaryotic proteins, as well as determining remaining novel folds. Determining protein structures through structural genomics increases understanding of protein function and facilitates drug discovery.
Brief Introduction of Protein-Protein Interactions (PPIs)Creative Proteomics
For more information, please visit https://www.creative-proteomics.com/services/protein-protein-interaction-networks.htm. Protein-protein interactions play important roles in various biological processes. PPIs can be classified based on different factors, including composition, affinity, and lifetime.
Molecular genetics: it deals with the structure, composition, function and replication of chromosomes and genes, representing genetics material like DNA and RNA.
Functional genomics uses high-throughput methods to study biological networks and network states at a genome-wide level. Key methods include microarrays to measure gene and protein expression, mass spectrometry to analyze proteomes, and techniques like yeast two-hybrid, co-immunoprecipitation followed by mass spectrometry, and ChIP-chip to map protein-protein and protein-DNA interaction networks. These functional genomics approaches generate large datasets that provide system-level understanding of biological processes and disease states.
This document outlines a presentation on protein-protein interaction networks, including predicting such networks, available interaction data sources, visualization and analysis tools. Methods for predicting networks include analyzing genomic sequences, 'omics' data, and literature. Popular tools for visualizing and analyzing networks include Cytoscape, VisANT, and tools for detecting network motifs and similarities. The presentation will demonstrate predicting a network from microarray data using ARACNE and visualizing it in Cytoscape.
This document discusses pathway and network analysis. It defines systems biology and biological networks. Some benefits of studying pathways and networks are that it improves statistical power, allows identification of potential causal mechanisms, and facilitates integration of multiple data types. Types of analysis include gene set enrichment and de novo network construction. Visualization is important for representing relationships between molecules and finding subnetworks. Software like Cytoscape can be used to import networks, map gene expression data to node colors/borders, filter networks, and export publication-quality images. A tutorial demonstrates combining expression and network data in Cytoscape to tell biological stories.
This document reviews protein-protein interactions (PPIs). It discusses how PPIs occur and their importance in biological processes. Several methods are described for identifying PPIs, including yeast two-hybrid systems, co-immunoprecipitation, and computational databases. PPIs help mediate cellular functions and understanding them can provide insight into diseases and new therapeutic approaches.
The Nucleic Acid Database provides structural references and a search engine for DNA and RNA structures. It depicts structures through systematic design based on biological data in tools like the RNA Viewer, Base Pair Viewer, and ATLAS. It also examines structures through innovative methods like the Musical Atlas, which uses musical algorithms to represent DNA structures as instrumental songs.
De novo genome assembly - T.Seemann - IMB winter school 2016 - brisbane, au ...Torsten Seemann
This document discusses de novo genome assembly, which is the process of reconstructing long genomic sequences from many short sequencing reads without the aid of a reference genome. It is challenging due to factors like short read lengths, repetitive sequences that complicate the assembly graph, and sequencing errors. The goals of assembly are to produce contiguous sequences with high completeness and correctness by resolving overlaps between reads into consensus sequences. Metrics like N50, core gene content, and read remapping are used to assess assembly quality.
Slightly modified version of slides on BWA-MEM2 that I presented at IPDPS'19 for the paper: Efficient Architecture-Aware Acceleration of BWA-MEM for Multicore Systems. Vasimuddin Md, Sanchit Misra, Heng Li, Srinivas Aluru. IEEE International Parallel and Distributed Processing Symposium (IPDPS), 2019.
Nadia Pisanti - With the recent New Genome Sequencing Technologies, Medicine and Biology are witnessing a revolution where Computer Science and Data Analysis play a crucial role. In this talk, I will give an overview of perspectives and challenges in this field.
This document discusses biochemical network mapping and visualization. It begins by describing the process of creating a metabolic network graph with nodes representing metabolites and edges representing reactions. While metabolic databases can provide information on known reactions, not all detected metabolites may be present. The document then introduces MetaMapp as an approach to map all detected metabolites into a network graph by combining information on known biochemical reactions with chemical similarity. Cytoscape software allows visualization and analysis of these network graphs. In conclusion, MetaMapp can be used to incorporate all identified metabolites into biochemical modules to aid in interpretation of omics data.
This document discusses metabolic network analysis and summarizes information from the KEGG database. It describes searching metabolic terms on Google and Google Scholar, keywords used in metabolic network analysis, and basic concepts in metabolic network reconstruction. It also provides an overview of the KEGG PATHWAY, MEDICUS, Mapper, and Expression databases and tools for mapping gene expression data onto metabolic pathways. The document concludes by assigning a report task analyzing gene expression data mapped to pathways using KEGG Expression and KegArray.
The biological databases document summarizes several important biological databases including BioGRID, Rfam, miRBase, and ModBase. BioGRID is a curated database of protein-protein and genetic interactions. Rfam contains information about RNA families and annotations for millions of RNA genes. miRBase is an archive of microRNA sequences and annotations that provides a central registry for assigning microRNA names. ModBase is a database of annotated protein structure models calculated in silico that may contain significant errors.
The document summarizes key concepts about gene expression and analysis. It describes the central dogma of biology where DNA is transcribed into RNA which is then translated into protein. Gene structure is explained, noting that eukaryotic genes contain introns and exons. The roles of DNA, RNA and proteins in gene expression are outlined. The processes of transcription, including initiation, elongation and termination are summarized. Post-transcriptional processing of RNA including capping, splicing and polyadenylation is covered. Translation including initiation, elongation and termination is also summarized concisely. Control of gene expression occurs at transcriptional, post-transcriptional, translational and post-translational levels.
The document summarizes a bioinformatics summer camp, including:
1. The camp will cover basic molecular biology and bioinformatics topics like DNA, proteins, gene expression and the genetic code.
2. Students will work on computational analysis projects involving whole genome sequencing, gene expression profiling, and functional and comparative genomics.
3. The camp will teach techniques for analyzing protein structures and interactions, gene expression data, and identifying pockets on protein surfaces.
Mascot is a software package from Matrix Science that interprets mass spectral data into protein identities.
In this presentation we will study about MASCOT and also on how to use it.
The document discusses various methods for structurally aligning proteins, including combinatorial extension, VAST, DALI, SSAP, and TM-align. It also describes Ramachandran plots, which show allowed and favored phi/psi dihedral angle combinations for protein backbone chains based on steric constraints. Structural alignment methods are useful for detecting evolutionary relationships between proteins with low sequence similarity. Ramachandran plots help validate protein structures by identifying conformations not allowed by steric hindrance.
dbSNP is a public archive of genetic polymorphisms including SNPs, insertions/deletions, and repeats. It contains contextual sequence information, frequency data, and experimental methods. dbSNP supports research areas like physical mapping, functional analysis, pharmacogenomics, and evolution. Variations are used as positional markers similar to STSs. Submitted SNPs are assigned IDs and aligned to reference genomes, clustering shared positions into reference SNP clusters. BLAST and FASTA tools allow searching. Null results of invariant sequences are also submitted.
This document discusses protein motifs and domains. It defines a motif as a recurring arrangement of secondary structure found in multiple proteins, such as the HTH, HLH, and hairpin motifs. A domain contains one or more well-characterized motifs and has an independent function. Two common motifs are described: the HTH motif, which contains two antiparallel alpha helices connected by a beta turn for DNA binding; and the HLH motif, which contains two helices connected by a loop, with the larger helix binding DNA and the smaller helix aiding folding. Domains are defined as distinct functional units that are evolutionarily conserved and can exist independently; they are classified based on secondary structure composition.
Structural genomics aims to determine the 3D structures of all proteins encoded by genomes through high-throughput methods. It uses a genome-based approach to solve protein structures rapidly and cost-effectively. Major initiatives like the Protein Structure Initiative have made progress in determining thousands of protein structures. Challenges include expressing membrane and eukaryotic proteins, as well as determining remaining novel folds. Determining protein structures through structural genomics increases understanding of protein function and facilitates drug discovery.
Brief Introduction of Protein-Protein Interactions (PPIs)Creative Proteomics
For more information, please visit https://www.creative-proteomics.com/services/protein-protein-interaction-networks.htm. Protein-protein interactions play important roles in various biological processes. PPIs can be classified based on different factors, including composition, affinity, and lifetime.
Molecular genetics: it deals with the structure, composition, function and replication of chromosomes and genes, representing genetics material like DNA and RNA.
Functional genomics uses high-throughput methods to study biological networks and network states at a genome-wide level. Key methods include microarrays to measure gene and protein expression, mass spectrometry to analyze proteomes, and techniques like yeast two-hybrid, co-immunoprecipitation followed by mass spectrometry, and ChIP-chip to map protein-protein and protein-DNA interaction networks. These functional genomics approaches generate large datasets that provide system-level understanding of biological processes and disease states.
This document outlines a presentation on protein-protein interaction networks, including predicting such networks, available interaction data sources, visualization and analysis tools. Methods for predicting networks include analyzing genomic sequences, 'omics' data, and literature. Popular tools for visualizing and analyzing networks include Cytoscape, VisANT, and tools for detecting network motifs and similarities. The presentation will demonstrate predicting a network from microarray data using ARACNE and visualizing it in Cytoscape.
Similar to Introduzione sulla system biology nel contesto delle biotecnologie moderne Tipologia e modelli dei network Genomica, proteomica e trascrittomica
Tesi laurea Cristian Randieri: TECNICHE DI SOFT COMPUTING PER LA MODELLISTICA...Cristian Randieri PhD
L’approccio classico nella modellizzazione matematica della realtà fisica si basa sull’utilizzo di leggi che descrivono il comportamento del sistema in studio. Tali leggi si esprimono generalmente nella imposizione di condizioni di equilibrio di forze agenti su parti infinitesime del sistema in esame. Le equazioni che così si ricavano sono tipicamente equazioni differenziali alle derivate parziali. Tali modelli però risultano molto complessi e di difficile applicazione quale ad esempio nella previsione degli inquinanti atmosferici. Pertanto molte delle volte non riescono a dare dei risultati in piccola scala ma si riferiscono ad osservazioni macroscopiche del sistema in esame.
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Introduzione sulla system biology nel contesto delle biotecnologie moderne Tipologia e modelli dei network Genomica, proteomica e trascrittomica
1. Biologia dei sistemi
Introduzione sulla system biology nel contesto delle biotecnologie moderne
Tipologia e modelli dei network
Genomica, proteomica e trascrittomica
Tomàs Prats Gambús
Biotecnologie
Università degli Studi di Parma
2. Concetti importanti
1. Introduzione alla biologia dei sistemi
2. Prospettiva storica
3. Principi basici
4. Top-down e bottom-up
5. Tecniche sperimentali
6. Modellazione di reti biologiche
7. Introduzione alle discipline “-OMICA”
8. Genomica
9. Proteomica
10.Trascrittomica
3. Introduzione alla biologia dei sistemi
- Si basa nella computazione e nella modellizazione dei diversi dati
sperimentali.
- Interazioni dinamiche tra le varie molecole (proteine e acidi nucleici).
- La crescita della bioinformatica ha facillitato la computazione dei diversi
dati scientifici.
4. Introduzione alla biologia dei sistemi
- Disciplina biologica che studia gli organismi viventi in quanto sistemi
che si evolvono nel tempo (nell’ interazione dinamica).
- Unendo nella pratica le conoscenze di genomica, proteomica,
trascrittomica e di teoria dei sistemi dinamici.
- Utilizza tecniche molecolare quali i microarray (determinare
cambiamento espressione genica).
- Anche tecniche biochimiche quale la spettrometria di massa o l’analisi
delle attività enzimatiche.
5. Prospettiva storica
- Gli studi della cinetica enzimatica iniziano nell 1900.
- A partire degli anni sessanta cominciano gli studi dei complessi molecolari
e delle teorie della biologia dei sistemi. (1960 Denis Noble svolse il primo
modello computazionale).
- Nel 1969 è la publicazione de “Teoria generali dei sistemi” di Ludwig von
Bertalanffy (il precursore della biologia dei sistemi).
- Nella decada de 1990, nasce la genomica funzionale che significò una
grande quantità di informazione genetica. Allo stesso tempo, che le
innovazione tecnologiche cominciavano a progressare velocemente.
- Nel decennio de 2000, si fa il progetto del genoma umano e inizia tutte le
discipline chiamate “-OMICA” come la metabolomiche o la proteomiche.
6. Obiettivi
- I modelli per svelare i meccanismi che causano fenotipi alterate e elaborare
nuove terapie e farmaci.
- Strumenti predittivi per la progettazione di cellule con proprietà desiderate
economico ed affidabile.
- Medicina individualizzata e predittiva.
7. Top-down e Bottom-up
- Strategie di elaborazione dell’informazione e di gestione delle conoscenze.
- Metodologie per analizzare situazioni problematiche (risoluzione di un problema
practico)
- Top-down: si formula inizialmente una visione generale del sistema, se ne
descrive la finalità principale, senza scendere nel dettaglio delle sue parti.
- Bottom-up: le parte individuali del sistema sono specificate in dettaglio, e dopo
connesse tra loro per formare componenti più grandi fino a realizzare un sistema
completo.
8. Top-down
La programmazione top-down è uno stile di programmazione in cui la
progettazione inizia specificando parti complesse e suddividendole
successivamente in parti più piccole.
Il nome top down significa dall'alto verso il basso: in "alto" viene posto il problema
e in "basso" i sottoproblemi che lo compongono.
Procedura:
Determinare direttamente l'obiettivo, individualizare le risorse necessarie,
precisare quelle disponibili e identificare quelle mancanti, proponere
successivamente ogni risorsa mancante come sub-obiettivo oppure come sotto-
problema in cui ciascun sub-obiettivo richiede una sub-strategia.
9. Bottom-up
Il bottom up richiama invece un'immagine raffigurante una freccia in cui la
coda è il bottom (la parte bassa) mentre up è la punta: dal punto di vista
dinamico si parte dal bottom e si procede verso up.
Considera l'obiettivo finale, induce a costruire un percorso sequenziale
organizzato in passaggi successivi in cui l'ancoraggio tra traguardi intermedi
e obiettivo finale è generalmente ricercato in modo intuitivo.
10. Tecniche sperimentali
1. Spettrometria di massa
La spettrometria di massa è utilizzata per identificare i composti sconosciuti e
quantificare composti noti in una soluzione.
- Un piccolo campione di composti è ionizzato, di solito per cationi dalla perdita
di un elettrone.
- Gli ioni sono ordinati e separati in base alla loro massa e carica.
- Gli ioni separati vengono rilevati e conteggiati, e i risultati vengono visualizzati
in un grafico.
11. Tecniche sperimentali
2. DNA Microarrays
- Si usa il DNA chip, è un metodo recentemente sviluppato per l'analisi high-
throughput di espressione genica
- Invece di guardare l'espressione di un singolo gene, microarrays permettono
di monitorare l'espressione di diverse migliaia di geni in un singolo
esperimento, con conseguente immagine globale dell'attività cellulare.
- Di conseguenza, essi rappresentano uno strumento fondamentale per
l'attuazione di un approccio di biologia dei sistemi.
13. Tecniche sperimentali
3. Yeast two-hybrid (Y2H)
- Il sistema del doppio ibrido di lievito è una tecnica di biologia molecolare
utilizzata per rilevare l'interazione tra le due proteine.
- La tecnica prevede l'attivazione di un gene reporter o più mediante l'azione di
un fattore di trascrizione alla sequenza regolatrice "UAS" (in inglese, sequenza
attivante a monte) situato a monte del promotore.
- Il fattore di trascrizione è diviso in due frammenti, uno che riconosce l'UAS e
altro promuovere l'attivazione del meccanismo di trascrizione. Ogni
frammento è fuso ad una proteina la cui interazione deve essere analizzato. Se
le proteine vengono complessati tra loro, i due frammenti del fattore di
trascrizione saranno trovati e il gene reporter si trascrivono.
15. Modellazione di reti biologiche
Lo scopo principale consiste nell’indentificazione con ragionevole accuratezza
delle interazione tra complesse molecolare a livello dei geni, proteine e metabolite.
1. Classificazione delle reti biologiche
- A livello molecolare (geni regolatori, interazione tra proteine, “signal
transduction”).
- A livello funzionale (immunologici o ecologici).
2. Rappresentazione delle reti
Instrumento utile per descrivere e visualizzare le reti è il “graph”.
16. Modellazione di reti biologiche
Grafo:
Un grafo è un insieme di elementi detti nodi o vertici che
possono essere collegati fra loro da linee chiamate archi o
lati o spigoli.
La distribuzione di grado, P (k), fornisce la probabilità che
un nodo selezionato ha esattamente k collegamenti.
Esso ci permette di distinguere tra le diverse classi di
rete.
Il “clustering coefficient” di un nodo (CI) misura
l’aggregazione delle sue “adjacents”. Misura l’isolamento
di un nodo.
17. Modellazione di reti biologiche
Concetto di modularità:
-Un gruppo di molecole fisicamente o funzionalmente collegati (nodi)
lavorano insieme per realizzare la stessa funzione.
-In una rappresentazione di rete, un modulo appare come un gruppo
altamente interconnesso di nodi.
- Il coefficiente di clustering può essere calcolato per quantificare
modularità.
- In assenza di modularità, il coefficiente di clustering delle reti reali e
“random” sono paragonabili.
- Alto “clustering coefficient”.
18. Modellazione di reti biologiche
3. Tipi di rete
3.1 Random networks:
- N nodi che connectano tra loro con probabilità p.
- Segue una distribuzione de Poisson.
- Molti nodi hanno lo stesso numero di collegamenti.
- Nodi con k più diverse hanno strani.
19. Modellazione di reti biologiche
3.2 Scale-free networks:
- La probabilità che un nodo è altamente collegato è
statisticamente più significativo che in un “random
networks”.
- Reti scale-free sono caratterizzati da una
distribuzione di grado legge di potenza. (power-law)
- La probabilità che un nodo abbia k links segue
dove y è il grado sponenziale.
20. Modellazione di reti biologiche
3.3 Hierarchical networks:
-“Hierarchical structure” pone in sistemi che combinano
topologia della modularità e “scale free.
- Si basa sulla replica di un piccolo gruppo di quattro nodi
(centrali).
- I nodi esterni sono collegati al nodo centrale del cluster
originale.
- Questa rete ha una distribuzione anche di grado legge di
potenza. (privo di scala).
21. Modellazione di reti biologiche
4. Significati reti biologiche
- Rete metaboliche
Nodi: prodotti metabolici
Archi: reazioni trasformando A in B
- Rete de regulazione trascripzionale (proteine-DNA)
Nodi: geni e proteine
Archi: a TF regula un gene
- Rete proteine-proteine
Nodi: proteine
Archi: interazioni tra proteine
- Rete regulazione genica
Nodi: geni
Archi: espressioni di A e B sono correlati
22. Modellazione di reti biologiche
Motifs:
-Patterns che si svolgono nella rete reale significativamente più spesso
che nelle reti randomizzati.
- Feed forward loop (FFL) è un motivo di rete della regolazione
trascrizionale da E.coli.
24. Introduzione alle -OMICA
-Ampio numero di discipline biomolecolari che presentano il suffisso "-
omica", come avviene per la interattomica o la metabolomica.
- In seguito alla diffusione di progetti di biologia quantitativa applicati
su larga scala (come il Progetto Genoma Umano), il suffisso "-oma" è
stato adottato dalle comunità dei bioinformatici e dei biologi molecolari.
25. Genomica
-Lo studio della struttura, il contenuto e l’
evoluzione dei genomi.
- Importante per interesse filogenetico e
agroalimentario, migliorare la conoscenza
umana, malattie genetiche.
- Conoscenza del numero di geni, la loro
organizzazione, funzione dei geni
conservati, regione d’omologia..
- Non essiste nessuna correlazione tra la
complessita d’un organismo e la
dimensione del suo genoma.
27. Trascrittomica
- È la disciplina che studia tutti i trascritti di una cella, e il suo valore, in una
determinata fase di sviluppo come in una particolare condizione fisiologica.
-Per analizzare si può fare:
- Un gene: northern blot, RT-PCR..
- Tutto il trascrittoma: microarrays, EST, RNA-Seq
- C’è un aspetto importante: ALTERNATIVE SPLICING
28. Proteomica
- La proteomica consiste nell'identificazione sistematica di proteine e nella
loro caratterizzazione rispetto a struttura, funzione, attività, quantità e
interazioni molecolari.
- Il proteoma è dinamico nel tempo, varia in risposta a fattori esterni e
differisce sostanzialmente tra i diversi tipi cellulari di uno stesso organismo.
- Mentre il genoma è un'entità costante, il proteoma differisce da cellula a
cellula ed è in continua evoluzione nelle sue continue interazioni con il
genoma e l'ambiente.
29.
30. Riferimento
1. Karp, P. D., and et al., Nucleic Acids Res., 28, 56 (2000).
2. Jeong, H., Tombor, B., Albert, R., Oltvai, Z., and Barabási, A.-L., Nature, 407, 651
(2000).
3. Jeong, H., Mason, S., Barabási, A.-L., and Oltvai, Z. N., Nature, 411, 41 (2001).
4. Kochen, M., editor, The Small World, Ablex, Norwood, NJ, 1989.
5. Wasserman, S., and Faust, K., Social Network Analysis: Methods and Applications,
Cambridge University, Cambridge, 1994.
6. Albert, R., Jeong, H., and Barabási, A.-L., Nature, 401, 130 (1999).
7. Lawrence, S., and Giles, C. L., Nature, 400, 107 (1999).
8. Kleinberg, J., Kumar, S. R., Raghavan, P., Rajagopalan, S., and Tomkins, A., Proc.
of the Int. Conf. on Combinatorics and Computing (1999).