Heat production during early development of frog egg

The production of heat in the fertilized eggs, during the early development of the Japanese pond frog, Rana brevipoda porosa, was measured using a pyroelectric detector constructed with a polyvinylidene fluoride film. One and 2 μW of heat production was detected during the cleavage periods in the embryogenesis of the 2-cell embryo and the 4-cell embryo, respectively. The heat production increased stepwise with the cleavage in the embryogenesis of each stage. In comparison with the heat production during the inter-cleavage periods, a larger amount was noted at the cleavage periods in the two embryonic stages.     

Effect of temperature on egg production in the common housefly

Musca domestica L. (Diptera: Muscidae), better known as the common housefly, is increasingly considered to be a new, alternative protein source for animal nutrition. By transferring low-value organic side streams into high-value protein products, its commercial production contributes to a circular economy. Next to technical innovations for scaling-up the production capacity, efficient egg production has been identified as one of the bottlenecks of housefly production systems. We investigated egg production in two strains, one originally from Spain (SPA) and one from The Netherlands (GK), at 25 and 32 °C. At 25 °C, duration of preoviposition period, laying phase, and adult longevity was longer than at 32 °C. Lifetime egg production was lower at 32 °C, but the number of clutches laid per female was unaffected by temperature. Daily egg production at 32 °C was higher during the first 7 days, revealing a trade-off between higher early-in-life reproductive effort and adult longevity. The combination of shorter sexual maturation period and higher daily egg-laying rate resulted in reaching 50% of total egg production only 6 days after emergence at 32 °C for both strains, compared to 13 and 14 days at 25 °C for SPA and GK, respectively. We conclude that, in the absence of a need for high adult survival rates, houseflies have favourable production performances at higher temperature, and that efficacy and yield of the production process could be maximized by increasing the rearing temperature to 32 °C.     

Tanycyte absorption affected by the hypothalamic deafferentation in Japanese quail,Coturnix coturnix japonica

In Japanese quail, Coturnix coturnix japonica the tanycytes of the median eminence absorbed peroxidase injected into the third ventricle. The number of tanycytes showing peroxidase reaction was greater in the posterior median eminence than in the anterior median eminence. Following hypothalamic deafferentation, the tanycyte absorption was augmented both in the posterior and anterior median eminence. These findings suggest that axons of some neurons, which have inhibitory action on the tanycyte absorption, were transected by deafferentation resulting in augmentation of tanycyte absorption. A considerable number of ependymal cells lining the upper portion of the third ventricle and those of the pars nervosa also absorbed peroxidase. In birds with a deafferented hypothalamus, photostimulated ovarian growth was completely inhibited.     

Role of nitric oxide in ovarian follicular development and egg production in Japanese quail (Coturnix coturnix japonica)

Role of nitric oxide (NO) in regulating the reproductive functions at hypothalamo-hypophysealovarian axis in Japanese quail was studied. In first experiment, metabolites of NO, i.e. nitrite and nitrate (NO2 and NO3) were estimated together in hypothalamus, serum and ovarian follicles of good and poor layers. In the second experiment, different NO modulators such as L-arginine (L-Arg), sodium nitroprusside (SNP) and N(G)-nitro-L-arginine methyl ester, HCl (L-NAME) were administered to the birds. In the first experiment, significantly higher (P < 0.01) NO2 and NO3 levels in serum, hypothalamus and largest (F1) ovarian follicles were observed in good layers as compared to poor layers. Higher (P < 0.05) NO2 and NO3 concentration was observed in F1 follicles than smaller follicles (F2) only in good layers. The NO2 and NO3 concentration was significantly reduced (P < 0.05) in post ovulatory follicles (POFs) in comparison to F1 and F2 follicles. In the second experiment, the serum NO2 and NO3 concentrations were higher (P < 0.05) in the SNP, lower (P < 0.05) in the L-Name group and unchanged in the L-Arg treated group in comparison to control group. compared to control, L-Arg and SNP increased (P < 0.05) the hypothalamic NO2 and NO3 concentration where as L-NAME reduced (P < 0.05) these levels. The NO2 and NO3 concentration was increased (P < 0.05) as the follicle size increased and it was significantly reduced (P < 0.05) in POFs. The higher (P < 0.05) follicular NO2 and NO3 concentration was observed in L-Arg group in comparison to control group. Egg production was also found to be higher (P < 0.05) in L-Arg group whereas it was not different (P > 0.05) in SNP and L-NAME treated groups. The yolk weight and yolk to albumin ratio was reduced (P < 0.05) in L-NAME group in comparison to control group. It may be concluded from the present study that NO plays a key role in regulating follicular development, ovulatory mechanisms and egg production in Japanese quail.     

Retinoic acid accelerates the development of reproductive organs and egg production in Japanese quail (Coturnix coturnix japonica)

The effects of retinoic acid on the development of reproductive organs and egg production in female Japanese quail (Coturnix coturnix japonica) were investigated. Female quail were fed a diet containing retinoic acid at 4 mg/kg (RA) or two diets containing retinyl acetate at 5000 IU/kg (VA1) or 14 000 IU/kg (VA2) after being fed a vitamin A-free diet for 2 wk (experiment 1). The oviduct and ovary grew more rapidly (P < 0.05) in RA-treated quail than in VA-treated quail at 5 wk of age. In addition, the body weight of RA-fed quail was also greater (P: < 0.05) than that of VA-fed quail at 5 wk. The RA-treated quail laid their first eggs approximately 5 days earlier (P < 0.05) than the VA-treated quail. Furthermore, these RA-fed quail laid more eggs (P < 0.05) than those VA-fed quail during the experimental period. To confirm the results of experiment 1, a similar experiment was conducted to record the first egg and total eggs laid by quail fed VA2 or RA (experiment 2). The early onset of oviposition was again observed in the RA-treated group (P < 0.01). These results suggest that retinoic acid has a stimulating effect on the reproductive system of female Japanese quail, as has been previously shown in the reproductive system of male Japanese quail.     

Growth of and fumitremorgin production by Neosartorya fischeri as affected by temperature, light, and water activity

The effects of temperature, light, and water activity (aw) on the growth and fumitremorgin production of a heat-resistant mold, Neosartorya fischeri, cultured on Czapek Yeast Autolysate agar (CYA) were studied for incubation periods of up to 74 days. Colonies were examined visually, and extracts of mycelia and CYA on which the mold was cultured were analyzed for mycotoxin content by high-performance liquid chromatography. Growth always resulted in the production of the tremorgenic mycotoxins verruculogen and fumitremorgins A and C. The optimum temperatures for the production of verruculogen and fumitremorgins A and C on CYA at pH 7.0 were 25, 30, and 37 degrees C, respectively. The production of fumitremorgin C by N. fischeri has not been previously reported. Fumitremorgin production was retarded at 15 degrees C, but an extension of the incubation period resulted in concentrations approaching those observed at 25 degrees C. Light clearly enhanced fumitremorgin production on CYA (pH 7.0, 25 degrees C), but not as dramatically as did the addition of glucose, fructose, or sucrose to CYA growth medium (pH 3.5, 25 degrees C). Growth and fumitremorgin production was greatest at aw of 0.980 on CYA supplemented with glucose or fructose and at aw of 0.990 on CYA supplemented with sucrose. Growth and fumitremorgin production were observed at aw as low as 0.925 on glucose-supplemented CYA but not at aw lower than 0.970 on CYA supplemented with sucrose. Verruculogen was produced in the highest amount on all test media, followed by fumitremorgin A and fumitremorgin C.     

Supplementary artificial light to increase egg production of geese under natural lighting conditions

A new supplementary lighting program was designed to increase the egg production of geese under natural light conditions. The objective of this study was to evaluate the effects of the supplementary lighting program on egg production of White Roman geese in an open housing system at the Tropic of Cancer. Forty mature White Roman geese were randomly allocated into two groups (male:female=1:4). The supplementary lighting program with a total daily photoperiod of between 12.0 h and 13.5 h was initiated on 1 November and withdrawn from the experimental group on 30 January. In contrast, the geese in the control group were kept under natural lighting conditions throughout this study. The results showed that the laying peak of the experimental group occurred earlier than normal in the reproductive season and the geese continued laying throughout the breeding season. The geese in the experimental group had 47.6 eggs/goose which was significantly (P<0.05) more than that of the control group having 26.4 eggs/goose. We can conclude that the supplemental lighting method will result in an earlier laying peak of the geese in the breeding season and higher egg production. The supplementary lighting program was able to maximize egg production in geese at the Tropic of Cancer.     

Loss or retention of chloroplast DNA in maize seedlings is affected by both light and genotype

We examined the chloroplast DNA (cpDNA) from plastids obtained from wild type maize (Zea mays L.) seedlings grown under different light conditions and from photosynthetic mutants grown under white light. The cpDNA was evaluated by real-time quantitative PCR, quantitative DNA fluorescence, and blot-hybridization following pulsed-field gel electrophoresis. The amount of DNA per plastid in light-grown seedlings declines greatly from stalk to leaf blade during proplastid-to-chloroplast development, and this decline is due to cpDNA degradation. In contrast, during proplastid-to-etioplast development in the dark, the cpDNA levels increase from the stalk to the blade. Our results suggest that DNA replication continues in the etioplasts of the upper regions of the stalk and in the leaves. The cpDNA level decreases rapidly, however, after dark-grown seedlings are transferred to light and the etioplasts develop into photosynthetically active chloroplasts. Light, therefore, triggers the degradation of DNA in maize chloroplasts. The cpDNA is retained in the leaf blade of seedlings grown under red, but not blue light. We suggest that light signaling pathways are involved in mediating cpDNA levels, and that red light promotes replication and inhibits degradation and blue light promotes degradation. For five of nine photosynthetic mutants, cpDNA levels in expanded leaves are higher than in wild type, indicating that nuclear genotype can affect the loss or retention of cpDNA.     

Growth of and fumitremorgin production by Neosartorya fischeri as affected by temperature, light, and water activity.

The effects of temperature, light, and water activity (aw) on the growth and fumitremorgin production of a heat-resistant mold, Neosartorya fischeri, cultured on Czapek Yeast Autolysate agar (CYA) were studied for incubation periods of up to 74 days. Colonies were examined visually, and extracts of mycelia and CYA on which the mold was cultured were analyzed for mycotoxin content by high-performance liquid chromatography. Growth always resulted in the production of the tremorgenic mycotoxins verruculogen and fumitremorgins A and C. The optimum temperatures for the production of verruculogen and fumitremorgins A and C on CYA at pH 7.0 were 25, 30, and 37 degrees C, respectively. The production of fumitremorgin C by N. fischeri has not been previously reported. Fumitremorgin production was retarded at 15 degrees C, but an extension of the incubation period resulted in concentrations approaching those observed at 25 degrees C. Light clearly enhanced fumitremorgin production on CYA (pH 7.0, 25 degrees C), but not as dramatically as did the addition of glucose, fructose, or sucrose to CYA growth medium (pH 3.5, 25 degrees C). Growth and fumitremorgin production was greatest at aw of 0.980 on CYA supplemented with glucose or fructose and at aw of 0.990 on CYA supplemented with sucrose. Growth and fumitremorgin production were observed at aw as low as 0.925 on glucose-supplemented CYA but not at aw lower than 0.970 on CYA supplemented with sucrose. Verruculogen was produced in the highest amount on all test media, followed by fumitremorgin A and fumitremorgin C.     

Observations on egg production by Toxocara pteropodis

Studies in juvenile Pteropus poliocephalus showed an average daily egg production by Toxocara pteropodis of 25,000 per female, with concentrations of up to 16,000 epg. regardless of whether eggs were fertile or infertile. Production commenced as early as 35 and as late as 48 days post-partum and rose to plateau average levels over about 10 days. For 23 days one bat passed infertile eggs which, over 2 days, were then replaced completely by fertile eggs. The implicit delay in maturation of a male nematode suggests that transmammary passage of larvae to suckling bats may persist for at least 3 weeks. Patency was terminated by the spontaneous expulsion of worms. If male worms were lost first, the egg output converted from fertile to 100% infertile within 48 h and the females were devoid of spermatozoa, suggesting that T. pteropodis copulate at least once daily. In prolonged infections, worm fecundity and egg fertility diminished, so that females with stored spermatozoa were producing mixtures of fertile and infertile eggs.     

Migratory orientation of European Robins is affected by the wavelength of light as well as by a magnetic pulse

The object of this study was to test the alternative hypotheses of magnetoreception by photopigments and magnetoreception based on magnetite. Migratory European Robins, Erithacus rubecula, were tested under light of different wavelengths; after these tests, they were subjected to a brief, strong magnetic pulse designed to alter the magnetization of single domain magnetite. In control tests under white light, the birds preferred the normal, seasonally appropriate migratory direction. Under 571 nm green light, they continued to be well oriented in the migratory direction, whereas under 633 nm red light, their behaviour was not different from random. The magnetic pulse had a significant effect on migratory orientation, but the response varied between individuals: some showed a persistent directional shift, while others exhibited a change in scatter; one bird was seemingly unaffected.These findings indicate a light-dependent process and, at the same time, suggest an involvement of magnetizable material in migratory orientation. They are in agreement with the model of a light-dependent compass and a magnetite-based map, even if some questions concerning the effect of the pulse remain open.     

Poly(ADP-ribose) polymerase is affected early by thyroid state during liver regeneration in rats

Poly(ADP-ribose) polymerase (PARP), a nuclear enzyme involved in DNA synthesis, DNA repair, and cell replication and transformation, also plays a role in the early steps of liver regeneration induced by partial hepatectomy (PH). PARP and DNA topoisomerase I (Topo I) activities and de novo DNA synthesis were studied during liver regeneration in rats with altered thyroid state. Hepatic PARP activity, evaluated as [(32)P]NAD incorporated into isolated liver nuclei, was inhibited in hyperthyroid rats and increased in hypothyroid animals. In both euthyroid and hyperthyroid rats PARP activity was rapidly stimulated, peaking 6 h after PH. In hypothyroid animals, an early decrease in activity was found, at a minimum of 6 h after PH, followed by an early onset of DNA synthesis. An inverse relationship between PARP and Topo I activities was a shared feature among euthyroid, hypothyroid, and hyperthyroid rats. Together these data show that, in replicating hepatocytes, thyroid hormones exert a regulatory role on PARP activity, which reflects the control of a number of nuclear proteins involved in DNA metabolism.     

Water chemistry in the microenvironment of rainbow trout Oncorhynchus mykiss embryos is affected by development,the egg capsule and crowding

The hypothesis tested was that embryonic metabolism affects the water chemistry in the boundary layer. In addition, embryo crowding would further compound the metabolic effect on the water chemistry in the boundary layer. As development progressed, the magnitude of the boundary layer gradients for O₂ and pH, but not for NH, increased. The presence of the egg capsule hindered the diffusion of O₂ into and H⁺ and NH out of the embryo. The magnitude of the O₂, pH and NH boundary layer gradient was significantly increased when embryos were surrounded by either sham embryos or live embryos. The majority of this crowding effect on embryo boundary layers was due to changes in water flow rather than due to metabolism directly. These results clearly show that the microenvironment adjacent to the developing rainbow trout Oncorhynchus mykiss embryo becomes more stagnant as development progresses in the presence of the egg capsule and is further intensified with embryo crowding.     

Survivin is essential for fertile egg production and female fertility in mice

Survivin is the smallest member of the inhibitor of apoptosis protein (IAP) family and acts as a bifunctional protein involved in mitosis regulation and apoptosis inhibition. To identify the physiological role of Survivin in female reproduction, we selectively disrupted Survivin expression in oocytes and granulosa cells (GCs), two major cell types in the ovary, by two different Cre-Loxp conditional knockout systems, and found that both led to defective female fertility. Survivin deletion in oocytes did not affect oocyte growth, viability and ovulation, but caused tetraploid egg production and thus female infertility. Further exploration revealed that Survivin was essential for regulating proper meiotic spindle organization, spindle assembly checkpoint activity, timely metaphase-to-anaphase transition and cytokinesis. Mutant mice with Survivin depleted in GCs showed reduced ovulation and subfertility, caused by defective follicular growth, increased follicular atresia and impaired luteinization. These findings suggest that Survivin has an important role in regulating folliculogenesis and oogenesis in the adult mouse ovary.