Environmental regulation of the reproductive system in a flexibly breeding Sonoran Desert bird, the Rufous-winged Sparrow, Aimophila carpalis

We investigated reproductive regulation in male Rufous-winged Sparrows, Aimophila carpalis, a Sonoran Desert passerine that breeds after irregular summer rains. Field and captive data demonstrate that increased photoperiod stimulates testicular development in March and maintains it until early September. Free-living birds caught in July and placed on captive long days (16L: 8D) maintained developed testes for up to 7 months, and free-living birds caught in September, during testicular regression, redeveloped testes when placed on captive long days, indicating that these birds were still photosensitive. Captive birds on long days maintained testicular development when exposed to temperatures mimicking those occurring during regression in free-living birds. In free-living birds, testicular development was observed during spring and summer, but unless this was associated with rainfall, breeding (indicated by juveniles) did not occur. Large increases in plasma luteinizing hormone (LH) in free-living males were correlated with heavy rainfall in July/August, when the birds bred, and in November, when they did not breed. In captive birds, plasma LH concentrations were unresponsive to photoperiodic changes, but may have responded to social cues. Plasma prolactin concentrations were directly correlated with photoperiod in free-living birds, but an effect of photoperiod on prolactin secretion was not seen in captive birds. It is concluded that male Rufous-winged Sparrows use long photoperiods to stimulate and maintain testicular development, but exposure to long photoperiods does not terminate breeding by inducing absolute photorefractoriness. The specific timing of reproductive behaviors is apparently determined by elevated plasma LH coinciding with long day stimulated gonad development.     

Seasonal changes in the reproductive and life-history traits of Chrysomela populi L. (Coleoptera: Chrysomelidae)

Seasonal changes in the reproductive and life‐history traits of Chrysomela populi L. were investigated in Shobara (34°52′N, 133°01′E), Japan, in 2004 and 2005. Larvae were hatched and reared under natural photoperiod and temperature in 8 different periods between late April and early September in 2004. The incidence of adult diapause increased with progression of the season in 2004. The critical timing of diapause induction, as defined by 50% of females entering diapause, was estimated to occur between late July and early August. No effects of season on the survival rate from hatching to adult emergence, percentage ovipositing females and percentage females that deposited viable eggs were clearly detected. Adult weight at emergence fluctuated seasonally, which was probably caused by air temperature. No effect of season on the oviposition period was observed among females that averted diapause. Females that entered diapause in 2004 started oviposition from the first day of May in 2005. Reproductive output was significantly greater in diapause females than in non‐diapause females. This increase in the reproductive output of diapause females was caused by elongation of the oviposition period and consequently by enlargement of the number of egg clutches deposited. These results suggest that the seasonal timing of diapause induction in females of C. populi would be affected by various risks and benefits to reproduction and survival.     

墨西哥帕丘卡卵胎生条纹强棱蜥的繁殖周期

本文报道墨西哥伊达尔戈州帕丘卡地区干旱环境中卵胎生条纹强棱蜥的繁殖周期及特征.测定墨西哥两个科学收藏馆的浸制标本获得数据.雌雄个体达到性成熟时的体长相等,为40.0 mm.雄体睾丸重量在5月开始增加,至7、8月达到最大.睾丸重量变化与降雨量、温度和光周期均无关.雌体卵泡重量在7月开始增加,并一直持续至10月.从11月至次年7月,雌体怀有胚胎.卵黄发生及胚胎发育与光周期、温度和降雨量无关.窝仔数与雌体体长呈正相关.平均窝仔数为5.2±0.2个(2-10个).     

Seasonal spermatogenic cycle and morphology of germ cells in the viviparous lizard Mabuya brachypoda (Squamata,Scincidae)

We describe seasonal variations of the histology of the seminiferous tubules and efferent ducts of the tropical, viviparous skink, Mabuya brachypoda, throughout the year. The specimens were collected monthly, in Nacajuca, Tabasco state, Mexico. The results revealed strong annual variations in testicular volume, stages of the germ cells, and diameter and height of the epithelia of seminiferous tubules and efferent ducts. Recrudescence was detected from November to December, when initial mitotic activity of spermatogonia in the seminiferous tubules were observed, coinciding with the decrease of temperature, photoperiod and rainy season. From January to February, early spermatogenesis continued and early primary and secondary spermatocytes were developing within the seminiferous epithelium. From March through April, numerous spermatids in metamorphosis were observed. Spermiogenesis was completed from May through July, which coincided with an increase in temperature, photoperiod, and rainfall. Regression occurred from August through September when testicular volume and spermatogenic activity decreased. During this time, the seminiferous epithelium decreased in thickness, and germ cell recruitment ceased, only Sertoli cells and spermatogonia were present in the epithelium. Throughout testicular regression spermatocytes and spermatids disappeared and the presence of cellular debris, and scattered spermatozoa were observed in the lumen. The regressed testes presented the total suspension of spermatogenesis. During October, the seminiferous tubules contained only spermatogonia and Sertoli cells, and the size of the lumen was reduced, giving the appearance that it was occluded. In concert with testis development, the efferent ducts were packed with spermatozoa from May through August. The epididymis was devoid of spermatozoa by September. M. brachypoda exhibited a prenuptial pattern, in which spermatogenesis preceded the mating season. The seasonal cycle variations of spermatogenesis in M. brachypoda are the result of a single extended spermiation event, which is characteristic of reptilian species. J. Morphol. © 2012 Wiley Periodicals, Inc.     

陕西榆林地区农田灯诱地下害虫种类组成及优势种群发生动态

为了明确陕西榆林地区农田地下害虫种类组成及优势种群发生动态,于2016年4月1日至2019年9月28日,在陕西省榆林市现代农业示范园,设置太阳能自动虫情测报箱对地下害虫进行收集,在室内对标本进行鉴定和数据分析。在榆林市农田一共灯诱到地下害虫12种,隶属3目5科。地下害虫混合种群发生期为4月中旬至9月上旬,盛发期为4月下旬至8月上旬。小地老虎Agrotis ypsilon、东方绢金龟Maladera orientalis、阔胫绢金龟Maladera verticalis和黄褐丽金龟Anomala exoleta是榆林农田地下害虫主要优势种群。小地老虎灯诱高峰期为4月上旬至5月中旬以及6月上旬至7月下旬,东方绢金龟的灯诱高峰期为4月中旬至6月中旬,阔胫绢金龟灯诱高峰期为6月上旬至8月上旬,黄褐丽金龟灯诱高峰期为6月中旬至7月上旬。本研究为榆林地区农田地下害虫的监测和综合治理提供了基础资料。     

Circadian and circannual changes in the testicular function of adult rhesus monkeys

The endocrine and gametogenic status of the testes were studied in 9 healthy adult rhesus monkeys of proven fertility throughout a one-year period. Testosterone levels were estimated by radioimmunoassay in blood samples collected at 4 h intervals over a 24 h period once a month. Semen samples and testicular biopsies were also examined once a month. A well-defined circandian rhythm was evident in serum levels of testosterone. The rhythmicity was less pronounced in February and September. The 24 h mean levels of serum testosterone were high between the months of August to March and low in the months of May to July. All animals did not uniformly respond to electro-ejaculation in April and May. Semen volume and total number of spermatozoa were maximal between September and March and least from April to August. Testicular biopsies indicated that all stages of spermatogenesis were evident between September and March and the spermatogenic activity was less evident between April and August. The contents of Sertoli cells showed a seasonal cyclicity; they were laden with lipid droplets during April to August when spermatogenesis was quiescent and vacuolated during September to March when spermatogenesis was active. These studies indicate that the testing of contraceptive drugs needs to be restricted to months of September to March in male rhesus monkeys otherwise, it is possible that the naturally occurring reproductive quiscence may be attributed to the effect of the drug being tested. The data accrued from the present studies also provide quantitative information on circulating levels of testosterone which could be used as a reference background while evaluating the contraceptive drug-effects in male rhesus monkeys.     

Anatomical and histological changes during dormancy in twococcinellidae

The gonads of both females and males ofSemiadalia undecimnotata Schneid, were studied during the estivo-hibernation period (August–May). The ovaries remain unripe in diapausing females, the ovarioles being formed by mere germaria until late April (or early May) when the previtellogenesis begins. In some years, the stage of the first oocyte is attained in females staying still in the hibernation quarters. On the contrary, both the spermatogenesis and spermateliosis proceed in the testes of diapausing males so long as the ambiant temperature is sufficiently high (August–September, April–May). Only in the coldest period of dormancy (November–March) the tissue of testicular follicles ceases to be active. Since mid-April the spermatogenesis and spermateliosis are resumed completely and the males fertilize the females, as is shown by dissections of their spermathecae. Seminal vesicles are always full of sperms. The digestive tract is empty in inactive coccinellids and the size of the fat body gradually diminishes in the course of estivo-hibernation.

The dependence of the activity of the tissue of testicular follicles on the ambient temperature was proved experimentally in bothS. undecimnotata andCoccinella septempunctata L. The temperature of +12°C enables a natural regression, while an abrupt transfer to +5°C renders gradual emptying of follicles impossible.

     

Influence of photoperiod on the seasonal pattern of secretion of luteinizing hormone and testosterone and on the antler cycle in roe deer (Capreolus capreolus).

Annual variations in concentrations of luteinizing hormone (LH) and testosterone in plasma were analysed in relation to the antler cycle in six adult male roe deer exposed to a natural photoperiod (latitude 46 degrees 10'N) and in four adult males maintained in a constant short-day photoperiod (8 h light: 16 h dark) for a year, from the winter solstice at which time both groups of animals had antlers in velvet. The animals were sampled, every 15 min for 2 or 4 h at intervals of one month for a year. Under both natural and experimental conditions, LH concentrations were high from January to March, but in the experimental conditions they decreased between April and May-June, whereas in the natural conditions they increased. Plasma LH concentration was lowest between July and November in animals under natural photoperiod, whereas under 8 h light:16 h dark photoperiod a second increase in plasma LH occurred between August and September. Between March and August, concentrations of plasma testosterone increased under natural photoperiod, whereas under experimental photoperiod there was a biphasic pattern of plasma testosterone with peaks between February and May and between September and November. Under natural photoperiod, antlers were cast in November, 369 +/- 6 days after the previous antlers were cast. Under experimental photoperiod, antlers were cast after 193 +/- 10 days, and a new set developed. The sexual cycle of the male appears to be initiated by an endogenous rhythm in winter and is then maintained by hormonal changes resulting from increasing photoperiod in spring.(ABSTRACT TRUNCATED AT 250 WORDS)     

Seasonal changes in moult,body mass and reproductive condition in siskins Carduelis spinus exposed to daylength regimes simulating different latitudes

Birds use change in daylength during the year to time events during their annual cycles. Individual Eurasian siskins Carduelis spinus can breed and winter in widely separated areas in different years. Birds at different latitudes will experience different changes in photoperiod. So how does latitude affect photoperiodic control? Our aim in this study was to find whether Siskins caught from the wild in Britain and exposed to different photoperiodic regimes, typical of widely separated latitudes, would differ in the subsequent timing and duration of their moults and associated processes. Siskins were caught in late February and early March, and initially kept outside on natural photoperiods. From the spring equinox (21 March), they were divided into three groups kept under photoperiodic regimes that simulated latitudes 40°, 55° and 70°N respectively. All three groups showed highly significant subsequent changes in body mass, fat scores and cloacal protuberance size. Moult of the primary feathers started during June – August (mean 9 July), and lasted 61–99 days (mean 75 days). Birds that started to moult late in the season had shorter moult durations. All individuals showed lower mass and fat levels during moult than before or after moult. Crucially, there were no significant differences in the timing of these events between the three photoperiodic groups. Apparently these birds did not use prevailing absolute photoperiod or the prevailing rate of change in photoperiod to time moult‐related seasonal events, but used instead some other feature of the annual photoperiod cycle or some form of interval timer linked to photoperiod.     

The seasonal changes in somatic energy content of Gulf of Alaska yellowfin sole, Pleuronectes asper

Seasonal measurement of body energy content was made for Pleuronectes asper (Pallas, 1814) from the Gulf of Alaska. Whole body energy content of complete fish (～ 3472 J g^?1 wet wt) was minimal in May for females as their overwintering phase ended, then increased to ～ 4456 J g^?1 prior to spawning. The ovarian index [(g.w./t.w.) × 100] and energy content of ovaries (J g^?1) was highest in June and May respectively, and then declined markedly by August as spawning occurred. Throughout the year male whole body energy content of complete fish ranged from 3351 to 4590 J g^?1 with the lowest values in May and highest values occurring during June to September, the feeding season. The testes index [(g.w./t.w.) × 100] and total energy content of testes (J g^?1) were high in March and lowest during June and July. On a weight-specific basis, males and females had similar whole body energy values throughout the year. Juveniles followed the same seasonal trends in energy storage as adults and had similar whole body energy values. Whole body energy content was linearly related to wet and dry weight condition factor with r² values of 0.70 and 0.87, respectively. Dry body weight as percent of wet body weight was the best predictor of body energy (r²=0.91). Yellowfin sole had an annual energy cycle with energy accumulation and growth from May to September. Thereafter they utilized stored energy for metabolic and reproductive needs. Spawning began in late May or early June and fish were spent by August. Whole body energy content increased by 28, 33 and 35% between May and June, for females, juveniles, and males, respectively, the most dramatic change during the year long survey. This suggests that intense feeding in May must be an important aspect of their energy storage cycle.     

Seasonally and experimentally induced changes in testicular function of the Australian bush rat (Rattus fuscipes)

Serum concentrations of LH, FSH and testosterone were measured monthly throughout the year in male bush rats. Testicular size and ultrastructure, LH/hCG, FSH and oestradiol receptors and the response of the pituitary to LHRH were also recorded. LH and FSH rose in parallel with an increase in testicular size after the winter solstice with peak gonadotrophin levels in the spring (September). The subsequent fall in LH and FSH levels was associated with a rise in serum testosterone which reached peak levels during summer (December and January). In February serum testosterone levels and testicular size declined in parallel, while the pituitary response to an LHRH injection was maximal during late summer. The number of LH/hCG, FSH and oestradiol receptors per testis were all greatly reduced in the regressed testes when compared to active testes. In a controlled environment of decreased lighting (shortened photoperiod), temperature and food quality, the testes of sexually active adult males regressed at any time of the year, the resultant testicular morphology and endocrine status being identical to that of wild rats in the non-breeding season. Full testicular regression was achieved only when the photoperiod, temperature and food quality were changed: experiments in which only one or two of these factors were altered failed to produce complete sexual regression.     

Superoxide dismutase, catalase, and glutathione peroxidase in the testis of the Mexican big-eared bat (Corynorhinus mexicanus) during its annual reproductive cycle

The reproductive physiology of Corynorhinus mexicanus includes a testes growth-involution cycle. Testis recrudescence begins in May-June, peaks in August and then undergoes a profound involution being totally regressed in November. Adult, male individuals were captured monthly during one year and ROS scavenging enzyme activities were measured in testes and expressed per total wet-weight and per mg protein. SOD total activity is very low from October to February; increases sharply one full month before testes recrudescence starts, and in August, when testis activity was at its peak, SOD is 3-4 times lower than in July. Catalase total activity is bimodal. The main peak of activity occurs during testicular recrudescence with an additional smaller peak, two months before the onset of recrudescence. Glutathione peroxidase total activity parallels almost exactly the testis growth cycle, increases in July, reaches a peak in August and decreases through September to almost disappear in October. SOD specific activity shows a pre-testicular increase of activity, maintains its activity from March to July and then descends drastically to almost nil in August, maintaining these low values until February. Catalase specific activity is particularly important during the period of testicular regression. GPX specific activity is low from March to July, months of testicular recrudescence; whereas its activity increases in August and peaks in November, when testes regression occurs. Our data show that ROS-scavenging enzymes may play a very important role during testes involution-recrudescence in C. mexicanus, and we believe their participation could be equally important in all seasonally breeding mammals.     

Adaptive significance of the recurrent photoperiodic response in a spring‐breeding carabid beetle,Carabus yaconinus

Seasonal changes in the photoperiodic sensitivity for reproduction in adults of a spring‐breeding carabid beetle, Carabus yaconinus (Coleoptera: Carabidae), were examined by transferring adults from outdoor to photoperiodic conditions in various seasons. Newly‐emerged adults transferred to the laboratory in September to December showed a long‐day photoperiodic response, but lost photoperiodic sensitivity gradually during winter. In late April, overwintered adults were not sensitive to the photoperiod, with females continuing to have mature eggs under both long‐day and short‐day conditions. In contrast, in late June and late July, the adults were sensitive to the photoperiod, with only those kept under short‐day conditions re‐entering reproductive diapause. This recovery of photoperiodic sensitivity appears to play a definitive role in maintenance of diapause in autumn for adults that have reproduced. The adults collected in late April regained photoperiodic sensitivity in two months even after being kept under unchanged conditions. Therefore, no environmental cue is required for recovery of photoperiodic sensitivity, which apparently recovers with the lapse of time. Our results suggest that the recurrent photoperiodic response is required in long‐living adults of C. yaconinus to regulate the timing of reproduction, and also indicate a difference in photoperiodic sensitivity in summer between overwintered and newly‐emerged adults.     

The annual testicular cycle in an equatorial colony of lesser rock hyrax, Heterohyrax brucei.

Adult males from a colony of lesser rock hyrax found near the equator in Kenya exhibited an annual cycle of testicular activity characterized by intense spermatogenesis and elevated androgen status from May to July. Average masses of testes and seminal vesicles taken in these months were almost fourfold greater than those from September to January. During the months of peak testicular activity average diameters of Leydig cells and seminiferous tubules were increased by approximately one half and total tubule length was doubled, compared with values for the quiescent months. Variable testicular development occurred during transitional intervals preceding and following peak testicular activity. From February to Aril thickening of the seminiferous epithelium and appearance of spermatozoa in the caput epididymidis signalled re-establishment of sperm production. In August shedding of germinal cells from the epithelium heralded impending failure of spermatogenesis. Evidence of an annual testicular cycle contradicted the prevalent belief that equatorial hyrax breed all year and suggested that the testicular cycle is a conservative element of hyracoid reproductive strategy.     

Reproduction in Schlieffen's bat, Nycticeius schlieffenii, in the eastern Transvaal lowveld, South Africa

The present study is based on 153 Schlieffen's bats collected over a 2-year period from September 1983 to September 1985. Spermatogenesis extends over a 10-month period with the first signs of spermatozoa in the epididymides by the end of April. Spermatozoa were present in the epididymides from the end of April until the beginning of September. Copulation begins during June (early winter) and the females have spermatozoa in the uterine horns from then until the end of August (late winter) when ovulation occurs. These bats are seasonally monoestrous with the great majority of births occurring during November. The number of conceptuses varied; a maximum of 5 pre-implanted embryos was recorded, but the maximum number of fetuses observed was 3.     

Evidence for an annual reproductive rhythm independent of food availability in male Creole goats in subtropical northern Mexico

The aim of this study was to determine if there is a seasonal pattern of sexual activity dependent on food availability in male Creole goats in subtropical Mexico. The study was conducted in the Laguna Region in the State of Coahuila, Mexico (26 degrees N). Male Creole goats (n = 8) were kept in a shed, fed alfalfa ad libitum and given 200 g of concentrate daily throughout the study. Live weight and testicular weight were determined every 2 wk. Sexual behavior and sperm production were determined monthly. Blood samples were obtained weekly to determine testosterone plasma concentrations. All variables were subjected to sinusoidal modeling procedures and showed important seasonal variations (P < 0.0001) with different phase angles for body weight, testicular weight and testosterone plasma concentrations. The nadir of live weight occurred in November and the peak in May. The lowest testicular weight (90 g) and testosterone plasma concentrations (0.1 ng/mL) were observed in January and February, respectively, while the peaks were observed in July and August (145 g and 10 ng/mL, respectively). Ejaculation latency also varied during the study, being low between May and November (96 sec) and reaching a peak in April (183 sec). Minimum number of spermatozoa per ejaculate occurred between February and April (1.4 x 10(9) cells/ejaculate) while the maximum number was observed between May and September (2.8 x 10(9) spermatozoa/ejaculate). Progressive sperm motility was low between January and April (3.04 on average) and high between May and November (about 3.55 on average). The percentage of live spermatozoa diminished between January and April (68% in April) and then increased to values around 80% between May and November. These results lead us to conclude that male Creole goats in Northern Mexico, fed constantly throughout the year, exhibit seasonality in their reproductive activity. Intense sexual activity occurred between May and December.     

雄性棕三趾鹑睾丸的年周期变化

2007年9月至2008年8月,于每月中旬从海南澄迈县取棕三趾鹑(Turnix suscitator)雄性成体8～11只进行解剖,观测性腺形态及其组织学特征.结果表明,棕三趾鹑睾丸重量和体积、曲细精管直径和生精上皮厚度呈周期性变化.3月睾丸明显增重增大,7月达到最大,10月明显变小减轻,12月最小.生精活动开始于3月,4～9月为旺盛的活跃期,从基膜到管腔,各级生精细胞依次排列,10月开始减弱,11月接近停止.根据睾丸各项指标的变化规律,显示棕三趾鹑11月至翌年2月为非繁殖期,3～10月为繁殖期.     

Photoperiodic regulation of reproductive development in male white-footed mice (Peromyscus leucopus) born at different phases of the breeding season

Male white-footed mice were maintained from birth in chambers equipped with latitudinal timers programmed to simulate the natural progression of daylengths at 42 degrees N latitude. Mice were born into photoperiods starting on 1 April, 15 July, 15 September or 27 October. Testes and seminal vesicles of April- and July-born mice were mature at 60 days of age; puberty was delayed by several months in animals born into the September and October photoperiods but these mice became fecund at about 3.5 months of age, independent of current photoperiod. Therefore, increasing daylengths of late winter do not appear to synchronize the reproductive development of overwintering juveniles born at different times during the previous breeding season.     

Seasonal anatomical variations in the testes of European pike, Esox lucius L.

The seasonal development of the testes in European pike was examined using wild fish and biopsies from pike housed in tanks. The size of the tubules and the different cell types were measured and their histological appearance described. Four stages of development can be distinguished during the annual cycle. They are: (I) the stage of rest from June to August; (II) the stage of development from September to November with intensive spermatogenesis; (III) the stage of maturity from December to March/April with spermatogenesis completed; and (IV) the post-spawning stage from March to May.     

Seasonal change in xylem growth of <Emphasis Type="Italic">Pinus densiflora</Emphasis> in central Japan

This study investigated the seasonal change in xylem growth of Japanese red pine (Pinus densiflora). Wood cores were sampled at 2-week intervals from April to November in 2012 using the microcoring method. Daily increment rates of tracheid number and tree-ring width were compared with seasonal changes in daily mean temperature and photoperiod. Xylem growth started in early to late May and stopped in late October to early November. The maximum daily increment rates of tracheid number and tree-ring width were in early July. The 95 % confidence intervals of the timing of the maximum daily increment rates included the summer solstice (23 June) with the longest photoperiod, but not the warmest day (30 July). The maximum daily increment rate of xylem growth is thought to be controlled by the photoperiod rather than by temperature. The daily mean temperature exceeded 20 °C after the summer solstice, indicating that temperature is not a limiting factor for xylem growth. This study suggests that the timing of maximum daily increment rates of xylem growth of P. densiflora is controlled by the photoperiod.