A couple of weeks back I talked about my new venture as a member of a Special Topics Network on Thermal Fertility Limits. This is a network of researchers interested in delving deeper into the mechanisms behind fertility failure following heat stress. I attended the first of three online meetings of the network and, after so many months at home with little interaction from a research perspective, it was so interesting and refreshing. We discussed a range of ideas around the topic and, as you'd expect, we had more questions than answers. We started off by asking: what do me mean with fertility? Do we intend viable eggs and sperm? Number of hatched young? Clutches of eggs? Then we moved on to thermal stress. Heat stress comes in lots of different forms, which one should we study? Long-term heat stress or short intense bursts? Should we be looking at a constant temperature, steady or sudden increase? If an animal/plant suffers damage, should be looking at irreversible damage or measure time to recovery? Are there sex differences (some initial evidence suggests there are)? Does it matter at what developmental stage heat stress happens? For insects, which undergo metamorphosis, early stages are usually immobile and less likely to be able to buffer damage caused by heat stress. Could this affect the lifespan of the individual post sexual maturity? There seem to be almost endless possibilities for student research! If you are interested please do get in touch to discuss this exciting and timely topic. I will be writing more as the network develops, meanwhile we will stay in touch and meet regularly.
0 Comments
A few months back, I was working on a manuscript (soon to be published) about work I have been doing during my Back to Science Fellowship. We ran different experimental treatments for our Indian meal moth cultures, heating them during their development and up to the point when, as adults, they were ready to mate. We found that sperm got shorter the higher the temperature we subjected the insect cultures to. This is interesting in itself because it is important to know how species will be affected by rising temperatures as the climate is changing. However, as I was reading the literature, I was surprised to learn that this pattern wasn't unique. I mean, I have been working on reproduction since my PhD, so I have done a fair bit of reading on the topic in general and yet, I had not noticed this pattern before. Let me explain. It is well known that male mammals are unable to produce sperm at body temperature, hence the reason why mammalian testes are usually located outside the body cavity - there are some exceptions to this pattern, for example in marine mammals, but these species have developed adaptations to cool the testes. However, what I was reading in the literature, was that when subjected to heat stress, male mammals and some male insects too, become infertile - and this is the interesting part - before the females do. So, you can mate females who have also been heat stressed to non-stressed males - and they can produce offspring but the reverse doesn't work, heat-stressed males are infertile. Somehow, spermatogenesis (the production of sperm) - and more generally gametogenesis (the production of gametes) too, as plants show the same trend - appears more sensitive to heat stress than oogenesis (the production of eggs). Then, in January, an opinion article came out that summarised exactly what I had been thinking. As I read it excitedly, I noticed that the authors had not picked up on the male/female differences on heat-stress sensitivity, so I wrote a comment. It is not only intriguing that males and females show different sensitivity to temperature stress, it may also tell us something about how species will be affected by climate change and how we might buffer or tackle these sensitivities. I am very keen to explore this further. So if you are a student, and this sounds interesting, please contact me. |
AuthorGraziella Iossa Archives
August 2023
Categories
All
|