One phase of the dormancy developmental pathway is critical for the evolution of insect seasonality

Evolutionary change in the timing of dormancy enables animals and plants to adapt to changing seasonal environments and can result in ecological speciation. Despite its clear biological importance, the mechanisms underlying the evolution of dormancy timing in animals remain poorly understood because of a lack of anatomical landmarks to discern which phase of dormancy an individual is experiencing. Taking advantage of the nearly universal characteristic of metabolic suppression during insect dormancy (diapause), we use patterns of respiratory metabolism to document physiological landmarks of dormancy and test which of the distinct phases of the dormancy developmental pathway contribute to a month‐long shift in diapause timing between a pair of incipient moth species. Here, we show that divergence in life cycle between the earlier‐emerging E‐strain and the later‐emerging Z‐strain of European corn borer (ECB) is clearly explained by a delay in the timing of the developmental transition from the diapause maintenance phase to the termination phase. Along with recent findings indicating that life‐cycle differences between ECB strains stem from allelic variation at a single sex‐linked locus, our results demonstrate how dramatic shifts in animal seasonality can result from simple developmental and genetic changes. Although characterizing the multiple phases of the diapause developmental programme in other locally adapted populations and species will undoubtedly yield surprises about the nature of animal dormancy, results in the ECB moth suggest that focusing on genetic variation in the timing of the dormancy termination phase may help explain how (or whether) organisms rapidly respond to global climate change, expand their ranges after accidental or managed introductions, undergo seasonal adaptation, or evolve into distinct species through allochronic isolation.     

Cell cycle regulation during development and dormancy in embryos of the annual killifish Austrofundulus limnaeus

Embryos of the annual killifish Austrofundulus limnaeus can enter into a state of metabolic dormancy, termed diapause, as a normal part of their development. In addition, these embryos can also survive for prolonged sojourns in the complete absence of oxygen. Dormant embryos support their metabolism using anaerobic metabolic pathways, regardless of oxygen availability. Dormancy in diapause is associated with high ATP and a positive cellular energy status, while anoxia causes a severe reduction in ATP content and large reductions in adenylate energy charge and ATP/ADP ratios. Most cells are arrested in the G₁/G₀ phase of the cell cycle during diapause and in response to oxygen deprivation. In this paper, we review what is known about the physiological and biochemical mechanisms that support metabolic dormancy in this species. We also highlight the great potential that this model holds for identifying novel therapies for human diseases such as heart attack, stroke and cancer.     

Effect of drinking earthen pot water on physiological response and behavior of sheep under heat stress

Heat stress is a major limiting factor for animal welfare and sheep production. Traditionally in India, the villagers used to keep their drinking water in the earthen pot to make it cold during summer. The cold drinking water (24–28 °C) during summer gives a feeling of relief from the heat. Therefore, the present study was carried out to assess the effect of drinking earthen pot water on physiological response and behavior of sheep under heat stress for one month. For this purpose, eighteen Avishaan rams were selected from the experimental animal flock and they were equally divided into three groups; viz., control (CON), heat stress (HS) and heat stress with earthen pot water (HSC). The animals of HS and HSC were exposed to higher ambient temperatures to induce heat stress inside the psychometric chamber. The animals of CON and HS were provided with ad-libitum water of their ambient temperature whereas; HSC groups were provided with ad-libitum cold water (24–28 °C) earthen pot water. All the animals were offered with 400 gm concentrate mixture and ad-libitum Cenchrus hay. The bodyweight of HS rams was significantly reduced (P < 0.05) at the end of the experimental period as compared to their initial body weight. The total roughage and dry matter intake was significantly higher (P < 0.01) in HSC rams as compared to HS rams. The plasma thyroxine concentration was significantly lower (P < 0.05) in HSC as compared with HS group. The rumination time significantly reduced (P < 0.05) in HSC group. However, The blood biochemical did not differ among the groups. Therefore, it may be concluded that Avishaan rams have the ability to adapt to heat stress. Nevertheless, the availability of earthen pot cold drinking water under heat stress reduced their body weight loss, improves their metabolic activity and ultimately improves their welfare.     

小麦吸浆虫保幼激素酯酶和保幼激素环氧水解酶基因的克隆及在滞育和变态发育过程中的表达动态

【目的】保幼激素(juvenile hormone, JH)在小麦吸浆虫Sitodiplosis mosellana滞育诱导及滞育后静息状态的维持中发挥着重要作用。保幼激素酯酶(hormone esterase, JHE)和保幼激素环氧水解酶(juvenile hormone epoxide hydrolase, JHEH)是调控JH滴度的重要降解酶。本研究旨在探讨JHE和JHEH在小麦吸浆虫滞育和变态发育中潜在功能。【方法】通过RT-PCR和RACE技术从小麦吸浆虫滞育前幼虫克隆JHE和JHEH全长cDNA序列;利用生物信息学软件分析其核苷酸及编码蛋白特性;采用qPCR技术分析其在小麦吸浆虫滞育不同时期(滞育前、滞育期、滞育后静息期和滞育后发育)3龄幼虫及1龄幼虫到成虫不同发育阶段(1-2龄幼虫、预蛹、初蛹、中蛹、后蛹、雌成虫和雄成虫)中的表达水平。【结果】克隆获得了cDNA全长分别为3 102和1 980 bp的小麦吸浆虫SmJHE和SmJHEH基因(GenBank登录号分别为MG876768和MG876769),其开放阅读框分别长1 740和1 371 bp,分别编码579和456个氨基酸,预测蛋白分子量分别为65.67和51.65 kD。SmJHE蛋白含有5个JHE家族特有的保守模块,SmJHEH含有催化三联体Asp228, Asp404和His431及组成阴氧离子洞的两个Tyr(Tyr299和Tyr374)和HGWP花样结构。序列比对和进化分析表明,SmJHE和SmJHEH均与双翅目(Diptera)长角亚目(Nematocera)昆虫同源蛋白氨基酸序列一致性较高,亲缘关系最近。不同滞育时期的表达模式表明,SmJHE和SmJHEH在滞育前期(1龄到滞育前的3龄幼虫早期)表达量变化不明显,进入滞育后表达量基本维持恒定,但均在滞育后静息阶段的当年12月至翌年1月最低。发育表达模式表明,幼虫恢复发育后SmJHE表达量逐渐升高,预蛹期达到最高,在雌成虫中的表达量显著低于雄成虫中的;SmJHEH表达量则在预蛹期最低,在雌成虫中最高。【结论】SmJHE和SmJHEH参与小麦吸浆虫滞育调控,其表达量的降低与滞育后静息阶段JH的累积有关;SmJHE在发育过程中表达量的升高可能参与幼虫到蛹的变态,表达量的降低可能与生殖发育有关。     

Environmental Cues,Endocrine Factors,and Reproductive Diapause in Male Insects

Environmental cues, mostly photoperiod and temperature, mediated by effects on the neuroendocrine system, control reproductive diapause in female insects. Arrest of oocyte development characterizes female reproductive diapause, which has two major adaptive functions: It improves chances of survival during unfavorable season(s), and/or it confines oviposition to that period of the year that is optimal for survival of the eggs and progeny. Although reproductive diapause is less well studied in male insects, there may be no sex-dependent differences in regard to the first of these functions. The second one, however, is not valid for the male; instead, selection pressure directs the male's reproductive strategy toward maximum chances of fertilization of the female's eggs with minimum waste of energy. Therefore, in species with female reproductive diapause, the males may or may not exhibit diapause, but if they do, their diapause must be adapted to that existing in conspecific females. Male reproductive diapause is defined as a reversible state of inability of the male to inseminate receptive females. In relation to reproductive diapause, there are several patterns of coadaptations between male reproductive strategy and timing of female receptivity, (a) In some insects, the females are receptive in the early part of their diapause; mating occurs during this period and there is no diapause in the male. The male dies shortly after copulation and the female stores the sperms to fertilize the eggs that develop after termination of the female's diapause, (b) In some species, as in the grasshopper Anacridium aegyptium, females are receptive during diapause; though oocyte development is arrested, copulation occurs and the stored sperms fertilize the eggs when the female's diapause ends. Males were claimed to have no diapause, but recent studies have revealed the presence of a reproductive diapause in a proportion of the males. This and other cases show that female receptivity during reproductive diapause may or may not be accompanied by male reproductive diapause. If there is a reproductive diapause in the male, it is controlled by the same endocrine mechanism, the corpora allata (CA), as in the females, (c) In many species females are refractory during their diapause. In these cases, males exhibit reproductive diapause, which may be light, as in the beetle Oulema melanopus, or well established, as in certain grasshoppers, butterflies, and beetles. In the latter cases, male diapause is controlled by similar environmental cues (photoperiod, temperature) and by the same intrinsic mechanism (neuroendocrine system, especially CA) as female diapause. Nevertheless, male diapause is less intense; the environmental cues leading to its termination are less complex and/or less extreme, so male diapause terminates before that of the females. Presumably, male diapause is under two antagonistic selection pressures: A male should not waste energy by courting dia-pausing refractory females, but he should be ready to copulate as soon as the females become receptive, otherwise he may lose in the competition between males for females. Some further strategies, which do not seem to fit the above patterns, are also outlined.     

Seasonal Effect on Infants' Sleep Regulation: A Preliminary Study in a Mediterranean Climate

Infants' sleep-wake rhythms are influenced by multiple factors, including developmental and contextual aspects, as well as circadian cycles. Empirical studies that address the seasonal impact on infants' sleep are scarce. The present study examined aspects of sleep schedule and quality, comparing summer and winter months in a Mediterranean climate. This report is based on a convenience sample of 34 healthy 7-mo-olds, an age in which sleep is well consolidated and regulated compared with the first few months of life. Sleep was measured with actigraphy, in the home context. It was found that compared with winter, in the summer months, sleep onset occurred at a later hour, and more motor activity during sleep was detected. Although the overall sleep quality, as defined by sleep efficiency score, was similar in the two seasons, in the summer, more active sleep was observed. The authors discuss the finding in terms of circadian rhythms, developmental characteristics, as well as possible environmental factors and family routines, and call for more studies, in different climates and geographical zones, and in different developmental periods. (Author correspondence: cohen.dini@gmail.com or anats@edu.haifa.ac.il)     

Interactions between climatic and production factors on returns of female pigs to service during summer in Japanese commercial breeding herds

The objectives of this study were to determine the associations between climatic factors and production factors for returns to service of female pigs during summer and to quantify the associations between these factors and occurrences of returns to service. The factors that were assessed were as follows: maximum temperature (HT), relative humidity, age of gilts at first mating, parity, weaning-to-first-mating interval (WMI), and lactation length. The study analyzed records of 18,307 gilts in 99 herds and 78,135 parity records of 56,322 sows in 103 herds; all the females were first-serviced between June and September, 2007 to 2009. Average daily HT and relative humidity for 15 days post-service of a female were obtained from 21 local weather stations and coordinated with the performance data of the respective local herds. The returns to service were categorized into three groups: regular returns (RRs: 18–24 days), irregular returns (IRs: 25–38 days), and late returns to service (LRs: 39 days or later). Two-level mixed-effects models were applied to the data by using a herd at level 2 and an individual record at level 1. In mated gilts, the occurrences (%) of RRs, IRs, and LRs were 4.8%, 1.8%, and 5.3%, respectively. In mated sows, the respective occurrences were 3.3%, 1.8%, and 4.2%. Mean values (ranges) of HT and relative humidity were 28.4 °C (13.6 °C–39.8 °C) and 73.4% (35.0%–98.0%), respectively. In gilts, as HT increased from 25 °C to 30 °C, the occurrence of RR increased from 3.7% to 4.4% (P < 0.05). However, there was no association between the occurrence of RR and either relative humidity (P = 0.17) or age at first mating (P = 0.23). In addition, there were no associations between the occurrences of either gilt IR or LR and HT (P ≥ 0.05), relative humidity (P ≥ 0.46), or age at first mating (P ≥ 0.32). In sows, greater occurrences of RRs, IRs, and LRs were associated with higher HT, lower parity, and a WMI of 7 days or longer (P < 0.05), but they were not associated with relative humidity (P ≥ 0.62) or lactation length (P ≥ 0.13). The occurrence of RRs in sows of all WMI groups increased 1.22 (1.04⁵) times for each 5 °C increase in HT. For sows with WMI 0 to 6 days, each 5 °C rise in HT increased the occurrence of IRs and LRs by 1.36 (1.06⁵) and 1.27 (1.05⁵) times, respectively. However, there was no association between increased HT and occurrences of IRs or LRs for sows with WMI 7 days or longer (P ≥ 0.38). Therefore, in order to prevent returns to service, it is recommended that producers apply cooling management for females during the post-service periods in summer.     

Extreme tolerance to environmental stress of sexual and parthenogenetic resting eggs of Eucypris virens (Crustacea,Ostracoda)

1. The freshwater ostracod (Ostracoda), Eucypris virens, is commonly found in European temporary pools, where its long‐term persistence completely relies on the build‐up of resting egg banks. Extreme tolerance of dormant eggs and seeds is widely assumed, but freshwater ostracod eggs are relatively poorly studied. The study of ostracod resting eggs is of particular relevance as it may yield the key to understanding the distribution of the sexes in many species capable of both sexual and asexual reproduction. 2. We assessed the tolerance of dried resting eggs produced by females originating from three populations with males and three all‐female E. virens populations. Hatching time and success was compared between control eggs and eggs exposed to one of seven ecologically relevant stressors: digestive enzymes, high salinity, deep freezing, hydration, UV‐B radiation, hypoxia and insecticide treatment. 3. None of the stressors reduced significantly the viability of either sexual or asexual eggs. When compared with the reproductive mode–specific controls, exposure to UV‐B radiation had a mild impact on the survival of sexual and asexual eggs (?16.8 and ?22.4%, respectively), but this was only significant for asexual eggs. These results point to an extreme tolerance of E. virens resting eggs and have important implications for the ecology and evolution of the species. 4. The timing of hatching was not affected by the stress treatment, except for UV‐B radiation. A marginally significant delay in hatching response was observed for UV‐B‐radiated eggs when compared to the overall mean, but this treatment effect was absent when compared with the reproductive mode–specific controls. 5. The populations with males produced eggs that hatched on average earlier (?1.5 days at 17 °C) and were more successful (+26%) than asexual eggs. Due to the limited number of populations and the population‐specific origin and age of the eggs, the possibility due to the differences in age and origin of the resting eggs, or to variations in local conditions, cannot be ruled out.     

Overwintering of Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) within target and non-target host eggs

Trichogramma ostriniae was imported into the USA from China and it continues to be evaluated as a biological control agent against the European corn borer and other lepidopteran pest species. A natural enemy's ability to overwinter is a facet of its biology with important ramifications for biological control and non-target effects. Thus, studies were conducted to examine the ability of the introduced egg parasitoid to survive over winters in central New York State. Eggs of Ostrinia nubilalis, Ephestia kuehniella, Trichoplusia ni, Helicoverpa zea and Utetheisa ornatrix were subjected to parasitism by adult T. ostriniae and then placed out of doors and exposed to winter conditions. For trials initiated in 2003 and 2004, the adult parental wasps were exposed to a diapause-inducing photoperiod and temperature regime in the laboratory; in 2010, parental wasps were conditioned out of doors and prior to the onset of winter conditions. Emergence of their progeny was monitored over time by taking aliquots of parasitised eggs, and holding them under warm conditions until emergence was complete. The level of wasp emergence generally displayed a decline followed by gradual increase until spring. Levels of overwintering ranged from 1% for O. nubilalis to 76% for E. kuehniella, and logistic regression indicated that the odds of overwintering was dependent on the year, host species, time out of doors and varied over exposure time depending on host. The potential to overwinter in New York was further confirmed by positive identification of T. ostriniae from naturally occurring O. nubilalis eggs collected from field sites where augmentative releases had been made in previous years.     

Induction of Non-diapause Eggs by Imidazole Derivative KK-42 in the Diapause Type of Bombyx mori Silkworm

The injection of an imidazole compound, KK-42, into fifth instar larvae of a silkworm (Bombyx mori, Daizo strain), which had been destined to produce diapause eggs, induced the moths to lay non-diapause eggs. The critical period for KK-42 injection in the induction of non-diapause eggs was 24 h to 72 h after the fourth ecdysis. Topical application of KK-42 to 48 h-old fifth instar larvae also induced non-diapause eggs.