Influence of incubation temperature and embryonic motility on the growth of members of Caiman yacare (Daudin, 1802)

This study aimed to evaluate whether skeletal development of the Pantanal Caiman (Caiman yacare) is similarly influenced by temperature variation and controlled increases in embryo motility. All eggs were incubated at 90% humidity and 29 °C for the first 45 days. Thereafter, the incubation temperature was either maintained at 29 °C and embryos were treated with 4-aminopyridine (4-AP) on days 46, 47, 48, and 49 (Group I, 29 °C 4-AP, n = 15); maintained at 29 °C (n = 14; Group II); or at 33 °C (n = 14, Group III). Embryonic movement was measured using an Egg Buddy® digital monitor on days 30, 35, 42, 49, 56, and 60, at which point embryos were euthanized and samples were collected for analysis. No differences were observed between groups with varying incubation temperatures. In contrast, embryonic motility was greater in embryos treated with 4-AP (P < 0.001) on day 49, and this was associated with higher proportions of snout-vent and hand lengths. This study demonstrates for the first time that pharmacologically induced increases in embryo motility result in phenotypic changes to the proportion of elements during prenatal ontogeny, thereby effectively altering the adaptation of the species to specific environments.

Do Incubation Temperatures Affect the Preferred Body Temperatures of Hatchling Velvet Geckos?

In many lizards, a mother’s choice of nest site can influence the thermal and hydric regimes experienced by developing embryos, which in turn can influence key traits putatively linked to fitness, such as body size, learning ability, and locomotor performance. Future increases in nest temperatures predicted under climate warming could potentially influence hatchling traits in many reptiles. In this study, we investigated whether future nest temperatures affected the thermal preferences of hatchling velvet geckos, Amalosia lesueurii. We incubated eggs under two fluctuating temperature treatments; the warm treatment mimicked temperatures of currently used communal nests (mean = 24.3°C, range 18.4–31.1°C), while the hot treatment (mean = 28.9°C, range 20.7–38.1°C) mimicked potential temperatures likely to occur during hot summers. We placed hatchlings inside a thermal gradient and measured their preferred body temperatures (Tbs) after they had access to food, and after they had fasted for 5 days. We found that hatchling feeding status significantly affected their preferred Tbs. Hatchlings maintained higher Tbs after feeding (mean = 30.6°C, interquartile range = 29.6–32.0°C) than when they had fasted for 5 d (mean = 25.8°C, interquartile range = 24.7–26.9°C). Surprisingly, we found that incubation temperatures did not influence the thermal preferences of hatchling velvet geckos. Hence, predicting how future changes in nest temperatures will affect reptiles will require a better understanding of how incubation and post-hatchling environments shape hatchling phenotypes.

Effects of constant incubation regimes on eggs and hatchlings of the egg-laying skink, Oligosoma suteri

<p>The conditions under which reptilian eggs are incubated affect survival probability and physiological attributes of the progeny. The egg-laying skink, Oligosoma suteri, is the only endemic oviparous lizard in New Zealand. No controlled laboratory incubation had previously been undertaken, and thus no information was available on the requirements for successful captive incubation. I studied the effects of incubation regime on the eggs and hatchlings of O. suteri to four months of age. Oligosoma suteri eggs (n = 174) were randomly distributed among three constant incubation temperatures (18°C, 22°C and 26°C) and two water potentials (-120 kPa and -270 kPa). Hatching success and hatchling survival were greatest at 22°C and 26°C, with hatchlings from 18°C incubation suffering from physical abnormalities. Incubation regime and maternal influence did not affect sex of individuals, with equal sex ratios occurring from each incubation treatment. Hatchlings from the 22°C and -120 kPa incubation treatments were larger, for most measurements, and warmer incubation temperatures resulted in increased growth rates. Juveniles from 22°C and 26°C and individuals with greater mass per unit length (condition index) sprinted faster over 0.25 m. Sprint speed was positively correlated with ambient temperature. At four months of age sprint speed decreased in 18°C individuals and individuals incubated at 26°C and -270 kPa compared to their performance at one month. The results suggest that the most successful captive incubation regime for O. suteri is 22°C and -120 kPa. This study also shows that temperature-dependent sex determination does not occur in O. suteri, but that fitness traits are influenced by incubation temperature.</p>

Effects of constant incubation regimes on eggs and hatchlings of the egg-laying skink, Oligosoma suteri

<p>The conditions under which reptilian eggs are incubated affect survival probability and physiological attributes of the progeny. The egg-laying skink, Oligosoma suteri, is the only endemic oviparous lizard in New Zealand. No controlled laboratory incubation had previously been undertaken, and thus no information was available on the requirements for successful captive incubation. I studied the effects of incubation regime on the eggs and hatchlings of O. suteri to four months of age. Oligosoma suteri eggs (n = 174) were randomly distributed among three constant incubation temperatures (18°C, 22°C and 26°C) and two water potentials (-120 kPa and -270 kPa). Hatching success and hatchling survival were greatest at 22°C and 26°C, with hatchlings from 18°C incubation suffering from physical abnormalities. Incubation regime and maternal influence did not affect sex of individuals, with equal sex ratios occurring from each incubation treatment. Hatchlings from the 22°C and -120 kPa incubation treatments were larger, for most measurements, and warmer incubation temperatures resulted in increased growth rates. Juveniles from 22°C and 26°C and individuals with greater mass per unit length (condition index) sprinted faster over 0.25 m. Sprint speed was positively correlated with ambient temperature. At four months of age sprint speed decreased in 18°C individuals and individuals incubated at 26°C and -270 kPa compared to their performance at one month. The results suggest that the most successful captive incubation regime for O. suteri is 22°C and -120 kPa. This study also shows that temperature-dependent sex determination does not occur in O. suteri, but that fitness traits are influenced by incubation temperature.</p>

Control of Escherichia coli O157:H7 Motility and Biofilm Formation by Salicylate and Decanoate: MarA/SoxS/Rob and pchE Interactions

Prophage-encoded Escherichia coli O157:H7 transcription factor (TF), PchE, inhibits biofilm formation and attachment to cultured epithelial cells by reducing curli fimbriae expression and increasing flagella expression. To identify pchE regulators that might be used in intervention strategies to reduce environmental persistence or host infections, we performed a computational search of O157:H7 strain PA20 pchE promoter sequences for binding sites used by known TFs. A common site shared by MarA/SoxS/Rob TFs was identified and the typical MarA/Rob inducers, salicylate and decanoate, were tested for biofilm and motility effects. Sodium salicylate, a proven biofilm inhibitor, but not sodium decanoate, strongly reduced O157:H7 biofilms by a pchE -independent mechanism. Both salicylate and decanoate enhanced O157:H7 motility dependent on pchE using media and incubation temperatures optimum for culturing human epithelial cells. However, induction of pchE by salicylate did not activate the SOS response. MarA/SoxS/Rob inducers provide new potential agents for controlling O157:H7 interactions with the host and its persistence in the environment. IMPORTANCE There is a need to develop E. coli serotype O157:H7 non-antibiotic interventions that do not precipitate the release and activation of virulence factor-encoded prophage and transferrable genetic elements. One method is to stimulate existing regulatory pathways that repress bacterial persistence and virulence genes. Here we show that certain inducers of MarA and Rob have that ability, working through both pchE -dependent and -independent pathways.

Feminization of Hawksbill Turtle hatchlings in the Twenty-first Century at an important Regional Nesting Aggregation

Projected climate change is forecasted to have significant effects on biological systems worldwide. Marine turtles in particular may be vulnerable, as the sex of their offspring is determined by their incubating temperature. This study is aimed to estimate historical and forecast future, primary sex ratios of hawksbill turtle hatchlings, Eretmochelys imbricata, in Qatar. Incubation temperatures were measured over two nesting seasons. Climate data from same period was regressed with nest temperatures to estimate incubation temperatures and hatchling sex ratios for the site from 1993 to 2100. Historical climate data showed female-biased sex ratios of 73.2 ±12.1% from 1993 to 2017. Female biases from 2018 to 2100 averaged 85.7% ±6.7%. In addition, predicted female hatchling production was >90% from 2054. These results show that hawksbill primary sex ratios in Qatar are at risk of significant feminization by the year 2100.

PSX-B-14 Properties of Kluyveromyces marxianus strains isolated from natural biotopes

Kluyveromyces marxianus yeast is often isolated from dairy products and used as probiotic agents in food. As a producer-yeast they must be genetically stable, have simple nutrient requirements, be effective in hostile conditions, grow on inexpensive nutrient media and be easy to store and distribute. Nineteen strains of K. marxianus isolated from natural biotopes were tested for their ability to grow on various carbon sources. For this, the YPD medium (1% yeast extract, 2% peptone, 2% dextrose, pH 5.5) was used with the addition of 20 g/L of one of the following carbon sources: glucose, sucrose, lactose, maltose, mannitol, arabinose, xylose, and galactose. The cultivation was carried out for 1–3 days. All isolates were also tested for their ability to grow in YPD broth at different temperatures (4, 27, 37, 40, 42, 46 and 48 °C) and pH (5; 3 and 2). K. marxianus strains showed widespread use of the substrate and high resistance to elevated incubation temperatures. All tested strains grew at 27 and 37 °C and one strain grew at 46 °C. None of the strains showed active growth at pH 2 and all cultures grew actively at pH 3. At the same time five strains showed growth at pH 5.0. All strains fermented galactose, 16 - xylose, 9 - glucose, 7 - lactose, 12 - maltose, 11 - arabinose, 5 - sucrose, 13 - mannitol. It should be noted that all strains in this study have showed fully restored growth after 2 hours’ incubation at pH 2. It indicates that they could survive when passing through the gastric passage into the intestine. These properties make the use of K. marxianus and its metabolites indispensable in agriculture as a feed additive. This work was supported by the Ministry of Science and Higher Education of Russia.

Developmental dynamics of sex reprogramming by high incubation temperatures in a dragon lizard

In some vertebrate species, gene-environment interactions can determine sex, driving bipotential gonads to differentiate into either ovaries or testes. In the central bearded dragon (Pogona vitticeps), the genetic influence of sex chromosomes (ZZ/ZW) can be overridden by high incubation temperatures, causing ZZ male to female sex reversal. Previous research showed ovotestes, a rare gonadal phenotype with traits of both sexes, develop during sex reversal, leading to the hypothesis that sex reversal relies on high temperature feminisation to outcompete the male genetic cue. To test this, we conducted temperature switching experiments at key developmental stages, and analysed the effect on gonadal phenotypes using histology and transcriptomics. We found sexual fate is more strongly influenced by the ZZ genotype than temperature. Any exposure to low temperatures (28oC) caused testes differentiation, whereas sex reversal required longer exposure to high temperatures. We revealed ovotestes exist along a spectrum of female-ness to male-ness at the transcriptional level. We found inter-individual variation in gene expression changes following temperature switches, suggesting both genetic sensitivity to, and the timing and duration of the temperature cue influences sex reversal. These findings bring new insights to the mechanisms underlying sex reversal, improving our understanding of thermosensitive sex systems in vertebrates.

Production of Natural Colorant by Monascus Purpureus FNCC 6008 using Rice and Cassava as Carbon Substrates

Consumer recognition of the adverse effects of synthetic colorant has increased awareness in utilizing natural colorants as an alternative. One of them is a microbial colorant and it is already studied for its safety and functional properties in the human body, i.e. hypercholesterolemia, antimicrobial, antioxidant, and anticancer. The functional properties of microbial colorant have driven many kinds of research about natural colorant produced by the microorganism. Monascus pigment is one of the popular red pigment synthesized by mold Monascus purpureus. This research was conducted to investigate the effects of particle size and incubation temperature on color value and water solubility of the natural colorant produced by M. purpureus FNCC 6008 using rice and cassava as carbon substrates. Every experiment was conducted in an erlenmeyer flask filled by 15 g of substrates, sterilized and incubated in an incubator chamber. Three particle sizes of 8, 10, and 16 mesh were employed on the incubation temperatures of 30, 32, and 34 oC for 14 days. Two parameters were measured from the sample to evaluate the results of the fermentation process, i.e. color intensity and water solubility of product. The highest color intensity of 59.6 CVU/gds was obtained from the rice substrate at the particle size of 10 mesh and incubation temperature of 32 oC. That particular fermentation condition resulted in a product with 71.4% product solubility.