Temperature shapes oviposition site selection and post-oviposition egg transport in an insect with parental care

Depositing eggs in an area with adequate temperature is often crucial for mothers and their offspring, as the eggs are immobile and therefore cannot avoid exposure to sub-optimal temperatures. However, the importance of temperature on oviposition site selection is less clear when mothers have the capability to avoid these potential adverse effects by both moving their eggs after oviposition and providing other forms of egg care. In this study, we addressed this question in the European earwig, an insect in which mothers care for the eggs during several months in winter and often move them during this period. Using 60 females from two Canadian populations (St John's and Harvey station) set up under controlled thermal gradients, we demonstrated that earwig females both select oviposition sites according to temperature and move their eggs after oviposition to reach warmer environmental temperatures. While this set of behavioural thermoregulation is present in the two studied populations, its modality of expression was population-specific: St John's females explored greater ranges of temperatures before oviposition, laid their eggs in warmer areas, and moved their eggs quicker toward warm locations. Overall, our study reveals that earwig females have evolved both pre-and post-oviposition behavioural strategies to mitigate the risks inherent to tending eggs during winter. More generally, it also reveals that egg care and egg transport do not prevent behavioural thermoregulation via oviposition site selection and highlights the diversity of behaviours that insects can adopt to enhance their tolerance to global climate change.

Mating induces early transcriptional response in the rat endosalpinx: the role of TNF and RA

During mating, males provide not only the spermatozoa to fertilize the oocyte but also other stimuli that are essential for initiating and maintaining the reproductive programme in females. In the mammalian oviduct, mating regulates sperm storage, egg transport, fertilization, early embryonic development, and oestradiol metabolism. However, the main molecules underlying these processes are poorly understood. Using microarray analyses, we identified 58 genes that were either induced or repressed by mating in the endosalpinx at 3 h post-stimulus. RT-qPCR confirmed that mating downregulated the expression of the Oas1h and Prim1 genes and upregulated the expression of the Ceacam1, Chad, Chst10, Slc5a3 and Slc26a4 genes. The functional category ‘cell-to-cell signalling and interaction’ was over-represented in this gene list. Network modelling identified TNF and all-trans retinoic acid (RA) as upstream regulators of the mating-induced transcriptional response, which was confirmed by intraoviductal injection of TNF or RA in unmated rats. It partially mimicked the transcriptional effect of mating in the rat endosalpinx. Furthermore, mating decreased RA levels in oviductal fluid, and RA-receptor-gamma (RARG) exhibited a nuclear location in oviductal epithelium in both unmated and mated rats, indicating RA-RARG transcriptional activity. In conclusion, the early transcriptional response regulated by mating in the rat endosalpinx is mediated by TNF and RA. These signalling molecules regulate a cohort of genes involved in ‘cell-to-cell signalling and interactions’ and merit further studies to understand the specific processes activated in the endosalpinx to sustain the events that occur in the mammalian oviduct early after mating.

UJI KUALITAS TELUR AYAM RAS DI KOTA MANOKWARI

A study was conducted to evaluate table eggs in Manokwari city. A total of 300 eggs were examined for external and internal qualities. The eggs were gathered from different places: local farmer for local eggs (1 respondent), markets for imported eggs (2 respondents)), supermarkets (4 respondents), egg distributors (1 respondent), and stalls (10 respondents)). The egg examinations were done twice, first was the time when no ship for egg transport came to Manokwari (period 1) to assume that the eggs had been kept for quite long before reached the consumers and second was the time when ship for egg transport that just arrived to Manokwari with the assumption that he eggs were still relatively fresh (periode 2). Results showed that the majority of table eggs in Manokwari had brown shells followed by spotted and light brown, all with oval shapes. Eggs gathered at period 2 were larger than those of period 1; local eggs were significantly heavier than imported eggs due to the difference of egg freshness. The local eggs of period 2 showed a very good air sac with AA quality, while the imported eggs had the air sac quality for A and B. The highest yolk score (8.88) were observed at local eggs at period 2.

Estradiol increases IP3 by a nongenomic mechanism in the smooth muscle cells from the rat oviduct

Estradiol (E2) accelerates egg transport by a nongenomic action, requiring activation of estrogen receptor (ER) and successive cAMP and IP3production in the rat oviduct. Furthermore, E2increases IP3production in primary cultures of oviductal smooth muscle cells. As smooth muscle cells are the mechanical effectors for the accelerated oocyte transport induced by E2in the oviduct, herein we determined the mechanism by which E2increases IP3in these cells. Inhibition of protein synthesis by Actinomycin D did not affect the E2-induced IP3increase, although this was blocked by the ER antagonist ICI182780 and the inhibitor of phospholipase C (PLC) ET-18-OCH3. Immunoelectron microscopy for ESR1 or ESR2 showed that these receptors were associated with the plasma membrane, indicating compatible localization with E2nongenomic actions in the smooth muscle cells. Furthermore, ESR1 but not ESR2 agonist mimicked the effect of E2on the IP3level. Finally, E2stimulated the activity of a protein associated with the contractile tone, calcium/calmodulin-dependent protein kinase II (CaMKII), in the smooth muscle cells. We conclude that E2increases IP3by a nongenomic action operated by ESR1 and that involves the activation of PLC in the smooth muscle cells of the rat oviduct. This E2effect is associated with CaMKII activation in the smooth muscle cells, suggesting that IP3and CaMKII are involved in the contractile activity necessary to accelerate oviductal egg transport.