Although birds have genetically determined sex, the sex ratio has been reported to deviate from parity in several studies. Temperature-dependent sex determination, which is common in reptiles, is absent in birds. However, females are able to adjust their investment into eggs according to the sex of the embryo, which may cause sex-specific embryonic mortality. Incubation temperature may also cause sex-biased embryonic mortality, and it may differentially affect the phenotype of male and female hatchlings. We aimed to investigate differences between male and female Mallard embryos regarding their egg size, mortality during incubation and hatchling phenotype in relation to incubation temperature. Mallard eggs were incubated under six constant incubation temperatures (ranging from 35.0 to 38.0 °C). Hatchlings were weighed, and their morphological traits were measured. We determined the sex of hatchlings and unhatched embryos by genetic analysis and found higher male embryonic mortality at 35.5 °C (44 males vs. 28 females) and a higher proportion of female hatchlings at 38 °C (24 males vs. 38 females); however, these results were not statistically significant. Our results suggest that Mallard females do not differentiate quantitatively between sexes during egg production. Male hatchlings were significantly larger but not heavier than females. The size difference between sexes was most pronounced at temperatures around 36 °C, which is the mean temperature of naturally incubated Mallard eggs.

• Klíčová slova
• Anas platyrhynchos, Egg quality, Incubation temperature, Phenotype, Reproduction, Sex,
• MeSH
• Anseriformes embryologie   fyziologie   MeSH
• drůbež embryologie   fyziologie   MeSH
• embryonální vývoj * MeSH
• inkubátory MeSH
• poměr pohlaví * MeSH
• teplota * MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Microbiome formation and assemblage are essential processes influencing proper embryonal and early-life development in neonates. In birds, transmission of microbes from the outer environment into the egg's interior has been found to shape embryo viability and hatchling phenotype. However, microbial transmission may be affected by egg-white antimicrobial proteins (AMPs), whose concentration and antimicrobial action are temperature-modulated. As both partial incubation and clutch covering with nest-lining feathers during the pre-incubation period can significantly alter temperature conditions acting on eggs, we experimentally investigated the effects of these behavioural mechanisms on concentrations of both the primary and most abundant egg-white AMPs (lysozyme and avidin) using mallard (Anas platyrhychos) eggs. In addition, we assessed whether concentrations of egg-white AMPs altered the probability and intensity of bacterial trans-shell penetration, thereby affecting hatchling morphological traits in vivo. We observed higher concentrations of lysozyme in partially incubated eggs. Clutch covering with nest-lining feathers had no effect on egg-white AMP concentration and we observed no association between concentration of egg-white lysozyme and avidin with either the probability or intensity of bacterial trans-shell penetration. The higher egg-white lysozyme concentration was associated with decreased scaled body mass index of hatchlings. These outcomes demonstrate that incubation prior to clutch completion in precocial birds can alter concentrations of particular egg-white AMPs, though with no effect on bacterial transmission into the egg in vivo. Furthermore, a higher egg white lysozyme concentration compromised hatchling body condition, suggesting a potential growth-regulating role of lysozyme during embryogenesis in precocial birds.

• Klíčová slova
• Albumen, Antimicrobial proteins, Bacterial penetration, Embryo viability, Incubation, Microorganisms, Temperature,
• Publikační typ
• časopisecké články MeSH

• MeSH
• bakteriologické techniky MeSH
• koncentrace vodíkových iontů MeSH
• teplota * MeSH
• Vibrio cholerae růst a vývoj   MeSH
• voda MeSH
• Yersinia pestis růst a vývoj   MeSH
• Yersinia růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• voda MeSH

The reproductive success of precocial birds depends on investments in clutch formation and incubation. Egg quality strongly affects the phenotypic traits correlated with survival of the hatchling, but parental ability to maintain incubation temperature can also influence hatchling outcomes. The effect of incubation temperature on hatchling phenotype has been widely studied in reptiles but not in birds. The aim of this study was to explore the effects of egg mass and incubation temperature on the incubation period, hatchability, and hatchling phenotype of the mallard (Anas platyrhynchos). Mallard eggs were incubated under six constant incubation temperatures (ranging from 35.0° to 39.0°C). Hatchlings were weighed, and their structural size was measured. Some hatchlings were used for an examination of residual yolk sac mass and basic chemical composition of the yolk-free body. All investigated phenotypic traits except for chemical composition were positively correlated with egg mass. Incubation temperature did not affect hatchling body mass, but increased temperatures led to a decreased yolk-free body mass and structural size of hatchlings and to increased yolk sac mass. Our results suggest that there is a trade-off between the yolk-free body size and energetic reserves in the form of the yolk sac and that this trade-off is modulated by incubation temperature.

• MeSH
• embryo nesavčí embryologie   MeSH
• embryonální vývoj fyziologie   MeSH
• fenotyp MeSH
• kachny embryologie   MeSH
• novorozená zvířata MeSH
• ovum chemie   MeSH
• teplota * MeSH
• velikost těla MeSH
• žloutkový vak chemie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Although variability in behavioral traits within animal populations is well documented, the mechanisms maintaining that variability are still insufficiently known. In this study, we examined whether differences in thermal environment during egg incubation can permanently organize nonsocial behavior across different contexts and situations in a lizard species. We incubated eggs of the Yucatan banded gecko, Coleonyx elegans (Squamata: Gekkota: Eublepharidae) at 3 constant temperatures (26, 28, and 30 °C) and raised juveniles separately under the same conditions until adulthood. We then subjected them to 3 behavioral tests within 2 different contexts: an open-field test and a test of antipredator behavior (stressful context) as well as a test of feeding behavior (nonstressful context). Individuals of both sexes incubated at 30 °C were consistently less active and showed lower frequencies of several stereotypic behaviors in the stressful contexts than did individuals incubated at 26 and 28 °C. The test of feeding behavior revealed no significant effect of incubation temperature on geckos' behavior. Thus, our study demonstrates that developmental plasticity may play an important role in producing variability in stress-induced behavior in lizards.

• MeSH
• chování zvířat fyziologie   MeSH
• ještěři fyziologie   MeSH
• ovum fyziologie   MeSH
• stravovací zvyklosti fyziologie   psychologie   MeSH
• teplota MeSH
• úniková reakce fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• cytopatogenní efekt virový MeSH
• inkubátory * MeSH
• kultivované buňky MeSH
• kuřecí embryo MeSH
• membrana vitellina MeSH
• teplota MeSH
• virus vakcinie patogenita   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

• MeSH
• inkubátory * MeSH
• kultivace virů MeSH
• kuřecí embryo MeSH
• rozmnožování * MeSH
• teplota MeSH
• virulence MeSH
• virus vakcinie růst a vývoj   MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

We studied the effect of increased initial incubation temperature and repeated preincubation of 35-d stored eggs from 46-week-old Ross 308 parental stock on the hatchability and day-old chick and yolk sac weight. Two different temperatures were applied during the first 36 h and they were combined with 4 preincubation treatments during storage. One half of the hatching eggs (2,400) were incubated for the first 36 h at an incubation temperature of 38.3°C, and the second half were incubated at a higher temperature of 39.2°C. Four different preincubations were applied; none, once at the 7th d of hatching egg storage, twice at the 7th and 12th d of storage and 3 times at the 7th, 12th and 19th d of storage. Both preincubation and increased temperature had negative effects on hatchability (P < 0.001). The interaction between these 2 factors was also significant (P < 0.05). These 2 factors also negatively affected early and late embryonic mortality (P < 0.001). However, middle embryonic mortality was not influenced. Live weight, weight of residual yolk sac, and yolk sac proportion were not affected by repeated preincubation nor by increased temperature over the first 36 h of incubation (P > 0.05). A higher initial temperature decreased chick yolk free body mass (P < 0.05). Although neither increased initial temperature in the setter nor repeated preincubation affected one-day-old chick weights, these treatments were not suitable for long-term stored eggs because of decreased hatchability and impairment of one day chick yolk free body mass.

• Klíčová slova
• embryonic mortality, hatchability, long-term egg storage, preincubation, yolk sac,
• MeSH
• kur domácí * MeSH
• ovum MeSH
• teplota MeSH
• vysoká teplota MeSH
• žloutkový vak * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Knowledge of embryo development is essential to the application of reproductive biotechnology in aquaculture, including for pikeperch Sander lucioperca. We describe pikeperch embryo development and demonstrated effects of temperature on the duration of embryogenesis. Developmental stages in embryos incubated at 15 °C were identified as zygote, 0-1.5 h post-fertilization (hpf); cleavage, 2.5-7.5 hpf; blastula, 9-18.75 hpf; gastrula, 21-39, hpf; segmentation, 45-105 hpf; and hatching, 125-197 hpf. Additional groups of eggs were fertilized and incubated at 10, 15, 20, and 25 °C to document stages of development, development rate, and survival. The optimal fertilization and incubation temperature was shown to be 15 °C, with the highest fertilization, survival, and hatching rates. Embryo development was slower at 10 °C, with 45% of fertilized embryos surviving to hatching. Development was accelerated at 20 °C, and resulted in a 56% survival rate of fertilized embryos. At 25 °C, embryos did not develop to the blastula stage. Pikeperch could be a valuable percid model for research in which flexible incubation temperatures is required.

• Klíčová slova
• Embryogenesis, Incubation, Insemination, Pikeperch, Temperature tolerance,
• MeSH
• embryo nesavčí fyziologie   MeSH
• embryonální vývoj MeSH
• Perciformes embryologie   MeSH
• teplota * MeSH
• voda * MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• voda * MeSH

Lactobacillus bulgaricus 59 and L. casei RTS and their respective nitrosoguanidine-induced mutants were estimated for titratable and volatile acidities, production of biacetyl and acetoin and for proteolytic activity. Both the mutants showed a marked increase in proteolytic activity as compared to the parents.

• MeSH
• kultivační média MeSH
• kyseliny karboxylové metabolismus   MeSH
• Lactobacillus genetika   metabolismus   MeSH
• mléčné bílkoviny metabolismus   MeSH
• mléko MeSH
• mutace MeSH
• teplota MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• kultivační média MeSH
• kyseliny karboxylové MeSH
• mléčné bílkoviny MeSH