The document summarizes autophagy and electron microscopy. It defines autophagy as the degradation of cells through lysosomes and discusses its importance in survival, cancer, and disease. Three forms of autophagy are identified: macroautophagy, microautophagy, and chaperone-mediated autophagy. Electron microscopes use electron beams for high magnification imaging of cells and materials. Transmission electron microscopes image thin samples while scanning electron microscopes image surface structure of bulk samples. Sample preparation for electron microscopy involves cleaning, coating, and thin film deposition depending on the analysis needs.

1. Kavita jaidiya
Rajuvas, Bikaner

2.  Autophagy is natural, conserverd, degradation
of the cell that removes unnecessary or
dysfunctional components through a
lysosome dependent regulated mechanism.
Autopahgy

3.  The concept emerged during 1960 s till
recently mechanism was not known.
 1990- Y. Ohsumni demostrated mechanism in
yeast.
History

4. Mechanism

5.  Three forms of autophagy have been
identified-
1) Macro autophagy
2) Micro autophagy
3) Chaperone mediated autophagy
Classification

7.  Autophagy functions as a survival mechanism
under various stress conditions, maintaining the
integrity of cells by recyclingessectial metabolites
and clearing debris.
 Autophagy cann both promote cancer growth
and act as a defence against cancer.
 Many pathogens are degraded by autophagy,
these include mycobacteria, shigella spp.
 Dysregulation of autophagy occurs in many
disease states including cancers, inflammatory
bowel disease and neurodegenerative disorders.
 Autophagy plays a role in host defense
against certain microbes.
Importance of Autophagy

8.  Etosis is a cell death mechanism defined by
the release of extracellular traps, which
can foster inflammation and exert
microbicidal activity.
Etosis

9.  Electrone microscope are used to
investigate the ultrastructure of wide range
of biological and inorganic specimens
including microorganisms cells, large
molecules, biopsy samples , metals and
crystals.
 Electroen microscope uses a beam of
electrons an image of the specimen.
 It is capable of much higher magnification
and has a greater resolving power than a
light microscope.

11.  There are two types of electrone
microscope-
1) Transmission electron microscope ( TEM)
2) Scanning electron microscope ( SEM)
 For SEM samples can be classified into
three categories-
1) Sample for fracture study
2) Sample for Microstructural study
3) Powder samples of morphology i.e size,
shapes of powder particles

12. For Fractography-
 Fracture sample is carefully cut according to
the size that specimen holder can accommodate.
 Sample is cleaned using some solvent eg.
Acetone, carbon tetrachloride, alchohal, oil,
grease , dust, oil or any other extraneous
material.
For Microscopical study-
 Sample of suitable size is taken.
 It is gound and polished than etched using
suitable etchant.
 Then cleaned etched sample is ready for
observation in the SEM.

13. For particle size and shape determination of
powder sample-
 The powder must be distributed evenly over a
clean substrate.
 A small quantity of powder is taken in test tube
filled with sovent or distilled water.
 Then it is agitated in ultrasonic cleaner to
disperse the particles, with the help of dropper
one or more drops of the solvent is dropped on
clean glass slides. When the slides is dried a
self adhesive conducting tapes is pressed
over the glass slide, so that all particles comes
out of slides, when tape is stripped out.
 The tape is then put on a mount and coated
with gold or carbon before examination in SEM.

14. For TEM-
 Thin film of material are prepared by physical vapour
deposition technique.
 The material is kept in a tungsten or Molybdenum basket
and clean substrate is place above or below the basket.
 The basket is then heated by passing current through it.
 When the material melts it evaporates and get deposits
on substrate.
 A clean glass slide coated with uniform layer of soap or
Nacl can be used as substrate.
 When thin flim is form on slide , it is striped out by
dipping the slide in distilled water .
 The soap and Nacl dissolve in distilled water and thin film
floats on water surface then can be loaded in TEM
specimen hloder and ready for examination.

15. Thank you
Kavita Jaidiya