Probability of pregnancy before ninety days postpartum in water buffaloes

This study aimed to determine the effect of parity and season of calving on the probability of water buffalo cows becoming pregnant before 90 days postpartum. A retrospective analysis of reproductive records of 1,465 water buffaloes with 3,181 pregnancies was carried out. Buffaloes were grouped according to parity in one, two, or three and more calvings. Season of calving was created with the following values: long photoperiod (March-August) and short photoperiod (September-February) and predicted probabilities from the mixed-effects logistic regression model were calculated, and a generalized linear mixed model was fitted with random intercepts to calculate the log odds of becoming pregnant ≤90 days postpartum. The probability of pregnancy ≤90 days postpartum was 0.3645, and this was lower in primiparous (0.2717) in comparison with two-calved (0.3863) and three or more calving buffaloes (0.5166). Probability of pregnancy ≤90 days postpartum increased 1.77 odds by each increase in parity. The probability of becoming pregnant ≤90 days postpartum was higher in water buffaloes calving during the short photoperiod season (0.4239 vs. 0.2474, P>0.000), and water buffaloes calving during the long photoperiod season only had 0.2645 odds to become pregnant than those calving during the short photoperiod season. The negative effect of long photoperiod was observed indifferently of parity. In conclusion, primiparity and the long photoperiod affect water buffalo cow's reproductive performance, decreasing pregnancy probability during the first 90 days postpartum.

Effects of illumination time on biological community of algal-bacterial granules and lipid content

Synthetic wastewater was used to culture granular sludge for 21 weeks at three sequencing batch reactor activated sludge process (SBR) under different photoperiods. The growth of algae changed granular oxygen distribution, which affected the composition of microbial communities. Different photoperiods were able to alter the formation of granular sludge and the microbial community granules. In short photoperiod (12 h/d) sludge could generate symbiotic algae-bacteria granules in the SBR. By contrast, the long photoperiod (24 h/d) promotes the growth of algae and Ascomycota early, and then inhibits algae, especially chlorophyta (only 1.18%). In the end, algae-bacteria-fungi granules were formed in long photoperiod (LP). By GC-MS and model calculation, the lipid content of algae-bacteria granules was 33.71% more than that of pure aerobic granular sludge. However, the proportion of unsaturated fatty acids in algae-bacteria granules was as high as 43%, resulting in the quality of biodiesel prepared from algae-bacteria granule being slightly worse than that prepared from pure aerobic granular sludge. But both of them were better than biodiesel prepared from pure algae. The biodiesel content of algae-bacteria granule in short photoperiod (SP) and LP were 68.79 and 70.66 mg/g, respectively, which was better than that of pure aerobic particles (52.30 mg/g). Therefore, the formation of algae-bacteria granules is an effective way to remove nutrients and reduce harvesting costs.

Reduced plasticity in coupling strength in the SCN clock in aging as revealed by Kuramoto modelling

The mammalian circadian clock is located in the suprachiasmatic nucleus (SCN) and consist of a network of coupled neurons, which are entrained to the environmental light-dark cycle. The phase coherence of the neurons is plastic and driven by the length of the day. With aging the capacity to behaviorally adapt to changes in the light regime reduces. The mechanisms underlying photoperiodic adaptation are largely unknown, but are important to unravel for the development of novel interventions to improve the quality of life of the elderly. We analyzed the neuronal synchronization of PER2::LUC protein expression in the SCN of young and old mice entrained to either long or short photoperiod and used the synchronization levels as input for a two-community noisy Kuramoto model. With the Kuramoto model we estimated the coupling strength between and within neuronal subpopulations. The model revealed that the coupling strength between and within subpopulations contributes to photoperiod induced changes in the phase relationship among neurons. We found that the SCN of young mice adapts in coupling strength over a large range, with low coupling strength in long photoperiod and higher coupling strength in short photoperiod. In aged mice we also found low coupling strength in long photoperiod, but strongly reduced capacity to reach high coupling strength in short photoperiod. The inability to respond with an increase in coupling strength shows that manipulation of photoperiod is not a suitable strategy to enhance clock function with aging. We conclude that the inability of aged mice to reach high coupling strength makes aged mice less capable to seasonal adaptation than young mice.

Body Temperature and Activity Adaptation of Short Photoperiod-Exposed Djungarian Hamsters (Phodopus sungorus): Timing, Traits, and Torpor

To survive the Siberian winter, Djungarian hamsters (Phodopus sungorus) adjust their behavior, morphology, and physiology to maintain energy balance. The reduction of body mass and the improvement of fur insulation are followed by the expression of spontaneous daily torpor, a state of reduced metabolism during the resting phase to save additional energy. Since these complex changes require time, the upcoming winter is anticipated via decreasing photoperiod. Yet, the extent of adaptation and torpor use is highly individual. In this study, adaptation was triggered by an artificially changed light regime under laboratory conditions with 20°C ambient temperature and food and water ad libitum. Two approaches analyzed data on weekly measured body mass and fur index as well as continuously recorded core body temperature and activity during: (1) the torpor period of 60 hamsters and (2) the entire adaptation period of 11 hamsters, aiming to identify parameters allowing (1) a better prediction of torpor expression in individuals during the torpor period as well as (2) an early estimation of the adaptation extent and torpor proneness. In approach 1, 46 torpor-expressing hamsters had a median torpor incidence of 0.3, covering the spectrum from no torpor to torpor every day within one representative week. Torpor use reduced the body temperature during both photo- and scotophase. Torpor was never expressed by 14 hamsters. They could be identified by a high, constant body temperature during the torpor period and a low body mass loss during adaptation to a short photoperiod. Already in the first week of short photoperiod, approach 2 revealed that the hamsters extended their activity over the prolonged scotophase, yet with reduced scotophase activity and body temperature. Over the entire adaptation period, scotophase activity and body temperature of the scoto- and photophases were further reduced, later accompanied by a body mass decline and winter fur development. Torpor was expressed by those hamsters with the most pronounced adaptations. These results provide insights into the preconditions and proximate stimuli of torpor expression. This knowledge will improve experimental planning and sampling for neuroendocrine and molecular research on torpor regulation and has the potential to facilitate acute torpor forecasting to eventually unravel torpor regulation processes.

The effect of responses to vernalization, photoperiodism, and earliness per se of barley accessions from Dagestan on the duration of the period from shooting to heading

Background. Paratypic variability of the development rates of barley accessions from the Republic of Dagestan was analyzed for five years in the Northwe st of Russia (Pushkin, St. Petersburg) and in the North Caucasus (Derbent, Dagestan). Responses to vernalization, photoperiodism and earliness per se were tested in contrasting environments to assess their effect on barley development. Such studies make it possible to identify valuable adaptable plant forms in the barley germplasm collection for further use in breeding practice.Materials and methods. In Dagestan, the duration of the period from shooting to heading was measured for 12 samples of barley accessions in winter and spring sowing trials. Twenty samples sown in spring in both regions were compared. An empirical indicator of plant development rate was used for barley: the criterion “the number of days by which the period from shooting to heading of an accession exceeds the minimum across a sample” (DPSH).Results and conclusions. Early barley accessions with a low norm of responsiveness were identified: k-3772, k-15013, k-15034, k-15036, k-15186, k-15192, k-21803 and k-23785 – they combined weak sensitivity to a short photoperiod and vernalizing temperatures, so they are promising for breeding in regions where the length of the growing season is a limiting factor. The effect of the responses of barley accessions from Dagestan to vernalization and a short photoperiod on the duration of the period from shooting to heading was on average 8 (5.1–10.6) days and on their earliness per se 6 (4.8–8.2) days. Paratypic variability reflects the range of variation for these indicators. In Dagestan, vernalization temperatures and insensitivity to a short day are the main factors determining the earliness of local barleys in their native environment.

Plasticity of nutrient accumulation patterns in diapausing fall webworm pupae

The accumulation of nutrients during diapause preparation is crucial because any lack of nutrition will reduce the likelihood of insects completing diapause, thereby decreasing their chances of survival and reproduction. The fall webworm, Hyphantria cunea, diapause as overwintering pupae and their diapause incidence and diapause intensity are regulated by the photoperiod. In this study, we test the hypothesis that photoperiod influences energy reserve accumulation during diapause preparation in fall webworm. We found that the body size and mass, lipid and carbohydrate content of pupae with a short photoperiod during the diapause induction phase were significantly greater than those of pupae with a relatively short photoperiod, and the efficiency of converting digested food and ingested food into body matter was greater in the short-photoperiod diapause-destined larvae than the relatively short-photoperiod diapause-destined larvae. We also observed higher lipase and amylase activities in short-photoperiod diapause-destined larvae relative to the counterparts. However, no obvious difference was found in protein and protease in the pupae with a short photoperiod during the diapause induction phase and short-photoperiod diapause-destined larvae compared with the counterparts. Therefore, we conclude that the energy reserve patterns of diapausing fall webworm pupae are plastic and that short-photoperiod diapause-destined larvae increase their energy reserves by improving their feeding efficiency and increase their lipid and carbohydrate stores by increasing the lipase and amylase activities in the midgut.

Polymorphism of winter phenotype in Siberian hamster: consecutive litters do not differ in photoresponsiveness but prolonged acclimation to long photoperiod inhibits winter molt

Background The theory of delayed life history effects assumes that phenotype of adult individual results from environmental conditions experienced at birth and as juvenile. In seasonal environments, being born late in the reproductive season affects timing of puberty, body condition, longevity, and fitness. We hypothesized that late-born individuals are more prone to respond to short photoperiod (SP) than early born ones. We used Siberian hamsters Phodopus sungorus, a model species characterized by high polymorphism of winter phenotype. We experimentally distinguished the effect of litter order (first or third) from the effect of exposure to long photoperiod (LP) before winter (3 months or 5 months) by manipulating the duration of LP acclimation in both litters. We predicted that, irrespective of the litter order, individuals exposed to long photoperiod for a short time have less time to gather energy resources and consequently are more prone to developing energy-conserving phenotypes. To assess effect of litter order, duration of acclimation to long days, and phenotype on basal cost of living we measured basal metabolic rate (BMR) of hamsters. Results Individuals born in third litters had faster growth rates and were bigger than individuals from first litters, but these differences vanished before transfer to SP. Litter order or duration of LP acclimation had no effects on torpor use or seasonal body mass changes, but prolonged acclimation to LP inhibited winter molting both in first and third litters. Moreover, individuals that did not molt had significantly higher BMR in SP than those which molted to white fur. Although one phenotype usually predominated within a litter, littermates were often heterogeneous. We also found that over 10% of individuals presented late response to short photoperiod. Conclusions Our data indicate that duration of postnatal exposure to LP may define propensity to photoresponsiveness, regardless of the litter in which animal was born. Existence of littermates presenting different phenotypes suggests a prudent reproductive strategy of investing into offspring of varied phenotypes, that might be favored depending on environmental conditions. This strategy could have evolved in response to living in stochastic environment.