Thermal Tolerance Of Eggs Research Articles

HSP70/DNAJ Family of Genes in the Brown Planthopper, Nilaparvata lugens: Diversity and Function.

Heat shock 70kDa proteins (HSP70s) and their cochaperones DNAJs are ubiquitous molecular chaperones, which function as the “HSP70/DNAJ machinery” in a myriad of biological processes. At present, a number of HSP70s have been classified in many species, but studies on DNAJs, especially in insects, are lacking. Here, we first systematically identified and characterized the HSP70 and DNAJ family members in the brown planthopper (BPH), Nilaparvata lugens, a destructive rice pest in Asia. A total of nine HSP70 and 31 DNAJ genes were identified in the BPH genome. Sequence and phylogenetic analyses revealed the high diversity of the NlDNAJ family. Additionally, spatio-temporal expression analysis showed that most NlHSP70 and NlDNAJ genes were highly expressed in the adult stage and gonads. Furthermore, RNA interference (RNAi) revealed that seven NlHSP70s and 10 NlDNAJs play indispensable roles in the nymphal development, oogenesis, and female fertility of N. lugens under physiological growth conditions; in addition, one HSP70 (NlHSP68) was found to be important in the thermal tolerance of eggs. Together, our results in this study shed more light on the biological roles of HSP70/DNAJ in regulating life cycle, coping with environmental stresses, and mediating the interactions within, or between, the two gene families in insects.

Relationship between Fish Size and Upper Thermal Tolerance

AbstractUsing critical thermal maximum (CTMax) tests, we examined the relationship between upper temperature tolerances and fish size (fry–adult or subadult lengths) of rainbow trout Oncorhynchus mykiss (41–200‐mm TL), Apache trout O. gilae apache (40–220‐mm TL), largemouth bass Micropterus salmoides (72–266‐mm TL), Nile tilapia Oreochromis niloticus (35–206‐mm TL), channel catfish Ictalurus punctatus (62–264 mm‐TL), and Rio Grande cutthroat trout O. clarkii virginalis (36–181‐mm TL). Rainbow trout and Apache trout were acclimated at 18°C, Rio Grande cutthroat trout were acclimated at 14°C, and Nile tilapia, largemouth bass, and channel catfish were acclimated at 25°C, all for 14 d. Critical thermal maximum temperatures were estimated and data were analyzed using simple linear regression. There was no significant relationship (P > 0.05) between thermal tolerance and length for Nile tilapia (P = 0.33), channel catfish (P = 0.55), rainbow trout (P = 0.76), or largemouth bass (P = 0.93) for the length ranges we tested. There was a significant negative relationship between thermal tolerance and length for Rio Grande cutthroat trout (R2 = 0.412, P < 0.001) and Apache trout (R2 = 0.1374, P = 0.028); however, the difference was less than 1°C across all lengths of Apache trout tested and about 1.3°C across all lengths of Rio Grande cutthroat trout tested. Because there was either no or at most a slight relationship between upper thermal tolerance and size, management and research decisions based on upper thermal tolerance should be similar for the range of sizes within each species we tested. However, the different sizes we tested only encompassed life stages ranging from fry to adult/subadult, so thermal tolerance of eggs, alevins, and larger adults should also be considered before making management decisions affecting an entire species.

Thermal Tolerance of Eggs and Larvae of Japanese Surf Clam Pseudocardium sachalinensis (SCHRENCK)

Thermal Tolerance of Eggs and Larvae of Japanese Surf Clam Pseudocardium sachalinensis (SCHRENCK)

Desiccation and thermal tolerance of eggs and the coexistence of competing mosquitoes

We tested the hypothesis that differences in temperature and desiccation tolerances of eggs of the container-dwelling mosquitoes Aedes albopictus and Aedes aegypti influence whether invading A. albopictus coexist with or exclude A. aegypti in Florida. In the laboratory, egg mortality through 30 days for A. albopictus was strongly temperature and humidity dependent, with low humidity and high temperature producing greatest mortality. In contrast, mortality through 30 days and through 60 days for A. aegypti was very low and independent of temperature and humidity. Mortality through 90 days for A. aegypti showed significant effects of both temperature and humidity. In the field, the proportion of vases occupied by A. albopictus was significantly lower at four of six sites at the start of the wet season (after a dry period) versus well into the wet season (after containers had held water for weeks). The proportion of vases occupied by A. aegypti was independent of when during the wet season vases were sampled. These results imply that dry periods cause disproportionately greater mortality of A. albopictus eggs compared to A. aegypti eggs. Container occupancy at tire and cemetery sites was significantly related to two principal components derived from longterm average climate data. Occupancy of containers by A. albopictus was greatest at cool sites with little or no dry season, and decreased significantly with increasing mean temperature and increasing number of dry months. In contrast, occupancy of containers by A. aegypti was lowest at cool sites with little or no dry season, and increased significantly with increasing mean temperature and increasing dry season length, and decreased significantly with total precipitation and number of wet months. We suggest that local coexistence of these species is possible because warm, dry climates favor A. aegypti and alleviate effects of competition from A. albopictus via differential mortality of A. albopictus eggs.

Développement et tolérance à la température des œufs deHeterobranchus longifilis, et comparaison des développements larvaires deH. longifiliset deClarias gariepinus(Teleostei, Clariidae)

Resume Development and thermal tolerance of eggs in Heterobranchus longfili.~, and comparison of larval developments of H. longifilis and Clarias gariepinus (Teleostei, Clariidae).

Thermal Tolerance of Eggs and Larvae of Hawaiian Striped Mullet, Mugil cephalus L.

Abstract Relationships between temperature and mortality of eggs and survival of the larvae are described for the striped mullet Mugil cephalus L. Eggs were incubated at temperatures between 1.0 and 40.5 C. Mortalities were least (4.2%) within the range 22.7-23.3 C. Hatching time was inversely related to temperature. The equation Y = 3.6674 − 1.5240 X describes the relation between incubation time and temperature over the range of 11-30 C. Larvae were exposed to temperatures between 2.7 and 32.9 C. Survival up to 12 days was greatest (19.9%) at a mean temperature of 24.9 C (range 24.5-25.3 C).