Animal Nutrition, and the start of Special Bacteriology (Day 159)

Gram Negative Bacteria - Pseudomonas aeruginosa gram stain under the microscope

Today’s Diary Entry is sponsored by Scampers Pet Shop

The end of week 1 of semester 2, this week has literally flown by and I am honestly not sure where my time has vanished too! Its been interesting as now instead of just looking at structures we are getting introduced into the things that cause diseases and how to treat them! Fundraising is starting to go well however I did struggle to fit everything I needed to do into this week.

Today I started a new topic in Animal Nutrition which will be spread over two semesters, and the next stage of microbiology – special bacteriology – which looks at specific disease causing bacteria each week. Now Animal Nutrition is basically looking at how food is used by an animal for energy to fuel the body processes and to promote health (physiologically it is split across structural, energetic and reserve functions). Within cats for example excessive vitamin A intake during pregnancy can cause the kittens to be born missing the palatine bone (cleft palate) which means they cannot form a vacuum and so cannot feed from their mom.

The introduction basically looked at the different components of food which looks something like this.

  • FOOD
    • Water
    • Dry Matter
      • Organic
        • Carbohydrates
        • Lipids
        • Proteins
        • Nucleic acids
        • Vitamins
      • Inorganic
        • Minerals

Obviously you can see from this that most of the nutritional value of food comes from the dry matter, this is why it is such a problem when supermarkets etc add extra water to their food products to increase the weight and charge more. Enough of that for today though.

Starting special bacteriology today there are a few words that I am always going remember that went something like this…

This semester you will be looking at different pathogenic bacteria in the laboratory, we only have a level 2 lab on the university campus so some of the bacteria you will read about only as it is too dangerous for our lab. about 30 minutes later Nesseria meningitidis is especially nasty as one day you go to work, the next day you are dead.

To be honest I am kinda glad that I am not in a lab working with N. meningitidis, I don’t mind working with dangerous stuff when I need to, but playing with something so deadly just to see what it looks like is not logical to me. Anyways back to today’s bacteria and we looked at the pseudomonadaceae, burkholderiaceae, neisseriaceae and legionellaceae families of bacteria in the theory lecture. In the lab however we only looked at pseudomonadaceae which can be classed as either pathogenic or non-pathogenic depending on the ability to destroy body tissues.

Gram Negative Bacteria - Pseudomonas aeruginosa gram stain under the microscope
Gram stain of Pseudomonas aeruginosa under the microscope with red staining rods

There are loads of different species of Pseudomonas not all of which cause disease and several that are opportunistic and only cause disease when they are given a chance by other things (aka cuts/weak immune system/stress etc).

Looking at Bacteria and Microbiological Staining (Day 22)


So Tuesday is solely Microbiology and Immunology, I kinda enjoy it as many of the why’s that previously confused me are being made clear. The morning starts with a lecture, before then having a practical session a couple of hours later. The lecture today was on the differences between the cell walls of Gram Negative and Gram Positive bacteria, I previously knew there was a difference, so am pleased to now actually understand it.

Talking about praticals here something I really do enjoy are the small group sizes, so for Microbiology there are just 9 of us in the lab meaning there is plenty of space to work. More importantly though it means that you get more time with the lecturer which means that stupid mistakes are corrected. Today for example when looking at motility (movement) of bacteria under the microscope I had pressed down a cover slip onto the microscope slide too hard squeezing all the saline suspension from the slide. After spending 5 minutes trying (and failing) to find the bacteria I was corrected and told to do it again without drying out the slide. When repeating it I rapidly found the bacteria, it may seem basic however its definately not a mistake that I will be making again.

microbiology-staining-practical-setupThe most basic way to look at bacteria is without staining, however like this you cannot view details. Probably the most common stain used is a gram stain, this is done in stages and uses different dyes to stain different bacteria different colors. The first dye is crystal violet which can be absorbed by both gram negative and gram positive bacteria and stains everything blue. The slide is then washed and Lugol solution is applied which makes the cell nuclie more visible before that is then also washed off. 95% ethyl alcohol is then applied which removes any excess dye, and in the case of gram negative bacteria can also cross the cell membrane to wash the crystal violet out from with the cell. The last dye applied is Carbolfuchsin which is red in color which then enters the empty gram negative cells to stain them red.

Gram Negative Bacteria
Gram Negative Bacteria

This evening I went to the anatomy self study which was pretty cool, basically the university opens up the dissection rooms between 5pm – 8pm on Tuesdays, Wednesdays and Thursdays for students to use under the supervision of student supervisors. We got to experience searching the bone cuboard for the bones from the thoracic limb (which was good revision in itself identifying the different bones). Being self study you are basically free to revise whatever you need to revise, and several second year students were revising the digestive tract and stomach and so had a goat dissection going on in one of the rooms which was pretty interesting to look at. I am still amazed at how vivid the colours of internal organs are!!!

Anyways I can relate all the structures on the Scapula now, and have started on the Humerus and Radius and Ulna (which is interesting as they are connected differently in different species). I will be back again tommorow night for sure as I am still not feeling as confident as I would like!