Effect of month and season of calving on the length of subsequent calving interval in Nili-Ravi buffaloes

Data pertaining to records of 1,274 calving intervals for 400 breeding buffaloes maintained at the Livestock Experiment Station, Qadirabad, District Sahiwal (Pakistan), were analyzed to investigate the magnitude of influence of month and season of calving on the length of subsequent calving interval. The longest average calving interval of 609.9 days was recorded for buffaloes calving in January, while the shortest average calving interval of 502.8 days was observed for those calving in June, the difference being highly significant (P < 0.01). When the data were split in accordance with season of calving, the calving intervals for buffaloes calving in winter, spring, summer and autumn averaged 569.1, 570.6, 506.6 and 515.7 days, respectively. The differences between intervals for winter and spring calvings and between intervals for summer and autumn calvings were non-significant. All other differences were highly significant (P < 0.01). Thus, in most of the buffaloes calving in winter or spring, the first post-partum oestrus and conception are delayed till the following autumn or winter, resulting in significantly longer calving intervals. In contrast, animals calving in summer or autumn exhibit post-partum heat and conception during autumn or winter, resulting in shorter calving intervals.     

The bionomics of the free-living larvae and the transmission of Dictyocaulus filaria between lambs in North-East England.

The bionomics of the free-living larvae of Dictyocaulus filaria on pasture, and the transmission of infection between lambs, were studied during different seasons of the year in North-East England. The rate of development of first-stage larvae to the third stage took 4-9 days in late spring and summer, 1 1/2-4 weeks in autumn and 5 1/2-7 weeks in winter. The proportion of first-stage larvae developing to the third stage ranged from 10-28% in autumn and winter, and 2-25% in spring and summer. The rate of mortality of the third-stage larvae was approximately logarithmic in nature, although the survival time was shorter in spring and summer than in autumn and winter. Third stage larvae were able to survive from autumn until the spring of the following year in sufficient numbers to perpetuate transmission but not to cause clinical disease. In a transmission study, the survival of the infective larvae on the experimental plot was poor in summer, but the larval population increased in the autumn and then declined slowly throughout the winter. Infection in the susceptible lambs was related to the level of infection on the herbage increasing in severity from early summer to late autumn. However, those lambs infected in the summer were resistant to the heavy autumn challenge of larvae on pasture.     

近55a来河西走廊荒漠绿洲区季节变化特征及其对胡杨年生长期的影响

利用河西走廊荒漠绿洲胡杨林集中分布区的4个气象站点1955-2009年日平均气温资料,采用5d滑动平均、气候倾向率、Mann-Kendall和滑动t检验等方法,分析其四季开始日与长度的变化特征及其对胡杨年生长期的影响。结果表明:近55a来,河西走廊荒漠绿洲区四季开始日主要表现为春、夏和秋季提早,冬季推迟的变化趋势,并以夏季提早最显著,且以21世纪初更突出。研究区平均四季长短变化特征为:冬季>夏季>春季>秋季。胡杨年生长期有开始日提早、终止日推后的趋势,且推迟趋势更明显;胡杨年生长期天数具有延长趋势。突变分析表明:春季开始日在1969年和2001年发生突变,夏、秋开始日则分别在1998年、 1985年和1997年发生突变,而冬季开始日发生突变的时间早于其它3季,为1985年;胡杨年生长期开始日具有多个突变,分别在1961年、1973年和1997年发生突变。显然,研究区胡杨对气候变化的响应更敏感。     

舟山海域大中型浮游动物群落时空变化及受控要素

为更好地保护舟山海域的渔业资源和生态环境,了解舟山海域浮游动物组成的时空变化,于2014年到2017年对舟山海域33个站位开展4个季节的生态综合调查,结果表明:4个航次共鉴定出浮游动物成体88种和浮游幼体19类,优势种共12种,浮游动物的优势种更替和群落特征季节变化明显,春夏、夏秋、秋冬、冬春相邻季节优势种更替率分别为75%、80%、100%和60%;平均生物量为夏季(176.34 mg/m³)>春季(120.20 mg/m³)和秋季(86.28 mg/m³)>冬季(7.21 mg/m³);平均丰度为夏季(143.97个/m³)>春季(86.30个/m³)>秋季(21.38个/m³)和冬季(26.86个/m³);平均多样性指数:夏季(3.03)>秋季(2.82)>春季(2.05)>冬季(1.71)。舟山海域浮游动物群落具有明显的季节和区域差异,温度、盐度、Chl a和营养盐是影响舟山浮游动物群落时空变化的主要环境因素,其中春季浮游动物群落空间分布主要受盐度的影响,夏季主要受温度、盐度和Chl a的影响,秋季主要受Chl a的影响,冬季主要受悬浮物和溶解氧的影响,而营养盐对每个季节的浮游动物群落分布都有一定的影响。     

基于MODIS-EVI的重庆植被覆盖时空分异特征研究

利用MODIS-EVI数据,采用像元二分模型结合距平百分率、变异系数和分布指数对2000—2015年重庆植被覆盖度变化时空分异特征进行了分析,结果表明:(1)重庆植被年际、夏、秋季和2008—2015年春季以中覆盖度为主,冬季以及2000—2007年春季以低覆盖度为主。(2)植被覆盖年际变化不明显;劣覆盖度在2000、2002、2003年春季,2001、2006年秋季以及2011年冬季异常偏多;低覆盖度在2000、2001年秋季异常偏多;高覆盖度在2000、2008年秋季和2014年春季异常偏少。(3)植被的波动变化除了冬季以中度为主外,年际、春、夏、秋季均以轻度为主;稳定比例最高为夏季,轻度比例最高为秋季,中度和重度比例最高为冬季。(4)稳定和轻度波动类型主要分布在山地森林和草地区,中度和重度波动类型主要是城镇、水域及其周边区域。在400m以下,植被变化为重度波动;在400—800m,植被年际和夏季趋于稳定分布,而春、秋、冬季为轻度波动;在800—1300m,植被年际和夏季为中度波动,春、秋、冬季为稳定分布;在1300m以上,植被年际和夏季呈现轻度波动,春季为中度波动,秋、冬季为稳定分布。     

Population dynamics of the cattle tick Rhipicephalus (Boophilus) microplus in a subtropical subhumid region of Argentina for use in the design of control strategies

The population dynamics of Rhipicephalus microplus (Ixodida: Ixodidae) in northwest Argentina was analysed to support the design of strategic methods for its control. Both parasitic and non‐parasitic phases were studied. The seasonal activity of R. microplus in its parasitic phase was characterized by three peaks in abundance: the first in mid–late spring; the second in summer, and the third in autumn. The non‐parasitic phase of R. microplus was characterized by a long total non‐parasitic period observed after exposures of females from mid‐summer to early autumn, a short total non‐parasitic period observed after exposures of females from late winter to late spring, a short period of larval longevity in early and mid‐summer, and no hatch of the eggs produced by females exposed in mid‐ and late autumn and winter. Treatments of cattle administered during the period from late winter to late spring will act on small cohorts of R. microplus, preventing the emergence of larger generations in summer and autumn. A 17‐week spelling period starting in late spring and early summer will be necessary to achieve optimal control of R. microplus free‐living larvae. If spelling begins in mid‐ or late summer or in autumn, the required period will be 26–27 weeks.     

Seasonal variations in the activity in vitro of peripheral blood granulocytes in the turtle Mauremys caspica

• 1.1. In the present work we have studied different aspects of the phagocytic process in peripheral blood granulocytes from the turtle Mauremys caspica: (a) tissue adherence capacity, (b) spontaneous mobility and chemotaxis, (c) attachment and ingestion of foreign cells (Candida albicans) or inert particles (latex beads), and (d) capacity to digest ingested material measured by nitroblue tetrazolium (NBT) reduction. These studies were carried out in vitro at 37°C in autumn, winter, spring and summer.
• 2.2. The adherence index showed significantly higher values in autumn, and smaller values in winter. The spontaneous mobility was not affected seasonally, but the chemotaxis was significantly increased in winter and decreased in autumn. The numbers of C. albicans attached and ingested as well as latex beads ingested per 100 granulocytes were higher in autumn and summer, and lower in winter and spring. The digestion capacity was greatly decreased in summer.
• 3.3. The comparison between the results obtained here and those found using the same techniques in blood human granulocytes showed that these animals are endowed with an adequate phagocytic response.

     

Seasonal and individual characteristics of the response of the fibrinolytic system of blood to physical exercise

The response of the fibrinolytic system of the blood of 33 untrained subjects (16 males and 17 females 18 years old) to a single 20-min bicycle-ergometric large-capacity load (N _male = 2.66 W/kg, N _female = 2.3 W/kg) was studied for 1 year. It is known that the blood fibrinolytic activity at rest has seasonal characteristics: it is relatively high in autumn and spring and low in winter and summer. On average, physical activity in winter and summer stimulates the blood clot lysis, whereas in autumn and spring this stimulation is not observed. The direction and intensity of the response of the fibrinolytic system to exercise have individual features: in autumn and spring they depend on its initial state (increase when the blood FA is low and decrease when it is high) and fluctuate widely, whereas in winter and summer this dependence is not observed. According to the direction of response to the load and its persistence, three types of responses can be distinguished: (a) hyperfibrinolytic, which is characterized by an increase in FA during exercise throughout the year, with a constantly low initial level of fibrinolytic activity at rest; (b) hypofibrinolytic, which is characterized by a stable suppression of fibrinolysis after exercise regardless of the season and the initial level of fibrinolytic activity, with a high fibrinolytic activity at rest in autumn and spring and a low fibrinolytic activity in winter and summer; and (c) unstable, in which the direction of the response of the fibrinolytic system to exercise varies. It is concluded that the development of thromboembolic complications after exercise can be expected with the highest and lowest probability in the subjects with the hypofibrinolytic and hyperfibrinolytic response, respectively.     

Spatial and seasonal changes of dissolved and particulate organic C in the North Sea

Sampling of the central region of the North Sea was carried out to study the spatial and seasonal changes of dissolved and particulate organic C (DOC and POC, respectively). The surface waters were collected during four cruises over a year (Autumn 2004–Summer 2005). DOC and POC concentrations were measured using high temperature catalytic oxidation methods. The surface water concentrations of DOC and POC were spatially and temporally variable. There were significantly different concentrations of DOC and POC between the inshore and offshore waters in winter and summer only, with no clear trend in autumn and spring. Highest mean concentrations of DOC were measured in spring with lower and similar mean concentrations for other seasons. POC showed a clear seasonal cycle throughout the year with highest surface mean concentrations found in autumn and spring, but lowest in winter and summer. The DOC distributions during autumn and spring were strongly correlated with chlorophyll suggesting extracellular release from phytoplankton was an important DOC source during these two seasons. The lower concentrations of DOC in summer were probably due to the heterotrophic uptake of labile DOC. The seasonal changes in the C:N molar ratios of surface DOM (dissolved organic matter) resulted in higher mean C:N molar ratios in spring and lower ratios in winter. These high ratios may indicate nutrient limitation of heterotrophic uptake immediately after the spring bloom. There is limited data available for DOC cycling in these productive shelf seas and these results show that DOC is a major component of the C cycle with partial decoupling of the DOC and DON cycling in the central North Sea during the spring bloom. Handling editor: Luigi Naselli-Flores     

The biology and epidemiology of Eimeria exigua, a parasite of wild rabbits invading the host cell nucleus.

Prevalence and intensity of infection with Eimeria exigua were studied by monthly sampling of caecal faeces of 254 wild rabbits (Oryctolagus cuniculus) from 5 localities in France (Arjuzanx, Versailles, Donzere-Mondragon, Massereau, Gerstheim) and by a single sampling in autumn in a small island off the coast of Britany (Beniguet). Intensity was heavier in young than in adult rabbits but usually remained low. It decreased from north to south, was at a maximum during autumn and winter, and declined in spring. Prevalences were relatively high and their rank (4th or 5th out of 10) was constant in all localities. Prevalences decreased from north-west to south-east; they increased progressively during autumn and winter, were at a maximum during spring and declined in summer. E. exigua developed in the ileum, at the top of the villi and inside the host-cell nucleus. It is distinguished from congeneric species by a number of features: micro-localisation, multiplication in autumn and winter rather than in summer, low intensity and high prevalence. These characteristics may be the consequence of a short schizogony phase and of strong resistance of oocysts.     

Annual changes in the concentration of minerals and organic compounds of Quercus suber leaves

Mature leaves are the primary source of sugars, which give rise to many secondary metabolites required for plant survival under adverse conditions. In order to study the interaction of field‐grown cork oak (Quercus suber L.) with the environment, we investigated the seasonal variation of minerals and organic metabolites in the leaves, using inductively coupled plasma atomic emission spectrometry, elemental analysis and nuclear magnetic resonance spectrometry. Statistical analysis showed that the data strongly correlated with seasonal climate and were divided in three groups corresponding to: (1) spring‐early summer, (2) summer and (3) autumn‐winter. The concentration of N, P, K and leaf ash content were highest in spring (recently formed leaves), reached the minimum during the hot and dry summer and increased slightly during the rainy period of autumn‐winter. Conversely, Na, Mg and Ca concentrations were lowest in spring‐early summer and increased during summer and autumn‐winter, the Ca concentration increasing five‐fold. Two cyclitol derivatives, quinic acid and quercitol were the major organic metabolites of the leaves. Their concentration along the season followed opposite trends. While quinic acid predominated during spring‐early summer, when it contributed 12% to the leaf osmotic potential, quercitol was predominant during autumn‐winter, when its contribution to leaf osmotic potential was about 10%. This different preponderance of the two compounds is expressed by the quercitol/quinic acid ratio, which can be as low as 0.2 in early summer and as high as 9 in winter. Sucrose and glucose concentrations also increased during autumn‐winter. Evidence for the quercitol protective role in plants during stress is discussed, and on the basis of structural similarity, it is suggested that quinic acid could have an identical importance, with a protective role against heat and high irradiance. It is concluded that the marked changes in Q. suber leaf composition throughout the year could have important implications in the plant capacity to endure climatic stress.     

福建北部近海浮游动物数量分布与水团季节变化的关系

根据2015—2016年在福建北部近海水域(120.10°E—120.65°E, 26.35°N—27.07°N)夏、秋、冬、春4个季节的海洋生态调查资料, 探讨了该水域浮游动物的数量分布、季节变化及其与水团变化的关系。结果表明, 调查水域浮游动物的平均生物量依次是: 夏季(479.51 mg/m3)>秋季(257.37 mg/m3)>春季(241.86 mg/m3)>冬季(84.05 mg/m3), 平均丰度依次是: 夏季(156.36 ind./m3)>春季(91.57 ind./m3)>秋季(40.34 ind./m3)>冬季(21.82 ind./m3), 生物量和丰度均值都呈现出夏季、秋季到冬季依次减少, 春季增多的趋势, 不同的是秋季生物量均值高于春季, 而丰度均值低于春季。在夏、冬和春三季, 浮游动物的总生物量和总丰度的分布总体较为一致; 而在秋季, 浮游动物的总生物量和总丰度的分布几乎相反。百陶箭虫(Sagitta bedoti)和微剌哲水蚤(Canthocalanus pauper)是影响夏季总丰度分布最主要的种类; 链钟水母(Desmophyes annectens)是影响秋季总丰度分布最主要的种类; 驼背隆哲水蚤(Acrocalanus gibber)、亚强真哲水蚤(Eucalanus subcrassus)和百陶箭虫对冬季总丰度的分布起到了重要影响; 五角水母(Muggiaea atlantica)和微剌哲水蚤是春季占总丰度比例较高的种类。浮游动物数量各季不同分布模式的根本原因是台湾暖流和浙闽沿岸流水团的季节性变化所致。研究结果不仅对了解与评价区域海洋生态系统动态和生物多样性变化具有重要的理论意义, 而且还可以丰富我国近海水域浮游动物的生态特征与水团变化之间的关系。     

Seasonal home range use by Japanese monkeys in the snowy Shiga heights

Between December 1974 and November 1975 (157 days), it was found that seasonal home range changes in the Shiga C troop were closely related to food changes, vegetation, and the existence of neighbouring troops. The detailed points clarified may be summarized as follows: (1) The seasonal home range sizes from winter to autumn were 1.23 km², 1.46 km², 1.69 km², and 1.21 km², respectively, and the annual size was 3.66 km²; (2) The food changed from bark and buds of trees in winter to young leaves and stems of grasses and trees in spring and summer, and fruits in autumn; (3) Each home range clearly changed according to the phenology of the plants used as food at each season; (4) The food abundance for the monkeys was extremely poor in winter, relatively poor in summer, plentiful in spring, and the best in autumn; and (5) The Shiga C troop and the neighbouring Shiga B₂ troop overlap in their home ranges in spring and autumn, but are separated during winter and summer.     

Seasonal changes in semen quality and freezability in the Warmblood stallion

The objective of this study was to investigate seasonal changes in stallion semen quality and to determine the best time for semen cryopreservation. Experiments were performed using 10 Warmblood stallions from the National Stud Farm in Avenches (Switzerland). Ejaculates were collected and frozen every other week during 1 year from January to December 1999. Volume, concentration, and motility, and the number of morphologically normal sperm and sperm with major defects (abnormal heads, acrosome defects, nuclear vacuoles, proximal droplets, abnormal midpieces) were evaluated. For all frozen-thawed semen samples motility as well as viability (SYBR-14/PI) was tested, and the hypoosmotic swelling test (HOS) was performed. To analyze seasonal differences 4 periods of 3 months each were defined: autumn (September, October, November), winter (December, January, February), spring (March, April, May) and summer (June, July, August). During the 1 year experiment all semen quality parameters showed a clear seasonal pattern. The volume, total sperm count and motility in fresh semen were significantly higher (P<0.05) in summer than in winter, while sperm concentration was significantly lower in summer compared to the other seasons. Regarding morphology, normal sperm was significantly lower (P<0.05) in summer than at any other time of the year and higher values (P<0.05) were found for major defects in summer than in spring and autumn. In frozen-thawed semen motility was significantly (P<0.05) improved in autumn when compared to spring and summer. Viability was lowest in summer and differed significantly (P<0.05) from other seasons. The HOS test revealed significantly more (P<0.05) membrane damaged spermatozoa in winter than in spring, summer and autumn. Our results demonstrate that in our climatic conditions clear seasonal differences occur in semen quality of fresh and frozen-thawed semen and that cryopreservation of stallion semen should preferably be performed in autumn.     

东海太平洋褶柔鱼生殖群体的空间分布及其与环境因子的关系

依据1997-2000年在东海(26°00′-33°00′N、120°30′-128°00′E)进行的4个季节的底拖网调查资料,分析了该海区太平洋褶柔鱼生殖群体的时空分布特征,同时结合广义相加模型(GAM),量化分析了各环境因子对于其种群成熟度指数(PMI)空间分布的影响机制。结果表明:太平洋褶柔鱼生殖群体春、夏、秋、冬4个季节在东海均有分布;秋季PMI值最高,春季最低;4个季节太平洋褶柔鱼生殖群体的分布范围均较广,主要集中在东海外海受台湾暖流和黑潮控制的水域。太平洋褶柔鱼生殖群体的环境适应性存在明显的季节差异:其分布的底温范围为:春季14.70-18.30℃、夏季13.18-20.91℃、秋季13.96-24.67℃、冬季14.33-19.75℃。底盐范围为:春季29.52-34.63、夏季31.57-34.27、秋季32.26-34.72、冬季34.25-34.70。水深范围为:春季55-179m,夏季43-176m、秋季40-184m、冬季79-152m。综上所述,东海太平洋褶柔鱼生殖群体的时空分布具有广范围、多季度的特点,这种分布特征可有效降低其幼体间的种间竞争,为确保其种群繁衍提供有利保障。     

Inhibition patterns and seasonal availability of nematodes for beef cattle grazing on argentina''s western pampas

The seasonal population trends of cattle nematodes in tracer calves are described from 1981 to 1987. Successive worm-free calves were grazed with growing beef cattle for 20–30 days at 6 week intervals and then slaughtered for nematode counts 2 weeks after their removal from pasture. Ostertagia, Cooperia, Trichostrongylus and Haemonchus were the main genera recovered. O.ostertagi was the most often found and acquisition of inhibition-prone larvae began in late winter and reached a peak in spring, while maximum larval availability was in autumn. The seasonal inhibition and larval availability pattern for T. axei was similar to that of Ostertagia. Cooperia showed greatest inhibition during winter with maximum larval availability in autumn and spring. Haemonchus was more prevalent during summer to early autumn and no inhibition was observed. It was concluded that infective larval availability for tracer calves was highest during autumn, and most reduced in summer. All predominant species were able to survive over summer on pasture,     

Community characteristics and of zooplankton in Qinzhou Bay

Qinzhou Bay, the biggest bay in Guangxi Province, is very species-rich and is developing a robust marine economy. In recent years, as human impact has increased, problems associated with the environment have become more complicated. Measuring zooplankton diversity and abundance is a way to monitor environmental conditions. According to the data from four ecological surveys of the zooplankton in Qinzhou Bay during 2008 and 2009, a total of 134 species of zooplankton were identified, including 52 Copepoda species, 27 Medusa species, 14 Planktonic larvae, 9 Chaetognatha species, 8 Pteropoda species, 5 Amphipoda species, 4 Cladocera species, 4 Ostracoda species, 3 Thaliacea species, 2 Appendiculata species, 2 Sergestdae species, 2 Protlsta species, 1 Rotiera species and 1 Cumacea species. The fauna was clearly characterized as tropical population. The total species number was highest in autumn, followed by spring, winter and summer. Zooplankton species diversity in Qinzhou Bay has increased compared with the results obtained in 1983–1985 (83 species). However, compared with other bays, the number of zooplankton species in Qinzhou Bay is close to Daya Bay (128), higher than in Zhilin Bay (60), Jiaozhou Bay (81) and Luoyuan Bay (70), and far lower than in the north South Sea (709). We adopted the dominant index Y > 0.02 as the distinguishing standard of dominant species. The number of dominant species in spring, summer, autumn and winter were six, nine, eight and five. There was only one common dominant species (Penilia avirostris) appeared in different seasons, For summer and autumn, the shared dominant species numbered about four. Between other seasons, the shared dominant species varied between two and three. The number of uniquely dominant species was four in summer, three in autumn and one in both spring and winter. The dominant species in different seasons have some overlaps and some differences. The average biomass of zooplankton was 378 mg/m³ at all times of year. The average biomass was largest in autumn, followed by winter, and was the least in spring and summer. The average density of zooplankton for the entire year was 805.11 ind/m³. The average density was largest in summer, followed by winter, and was least in autumn and spring. Copepoda and Planktonic larvae were the major components of zooplankton in spring and summer at Qinzhou Bay, with the other species’ densities under 10%. In autumn, Copepoda, Planktonic larvae and Chaetognatha were the major components of the biomass, and in winter, the major species were Copepoda and Cladocera, with the others species’ density under 10%. The average value of the Shannon–Wiener diversity index (H′) was 3.84 and the evenness index (J′) was 0.77. The zooplankton diversity index and community evenness overall were good and the community organization had a complete and stable state, but the status of the community was relatively weak. The relationship between biomass/density of zooplankton and environmental factors is remarkable. Biomass and density are positively correlated with temperature and nutrient concentration, and are negatively correlated with salinity.     

Season of ejaculate collection influences the freezability of boar spermatozoa

The aim of this retrospective study was to evaluate whether the season of ejaculate collection influences the freezability of porcine sperm. A total of 434 ejaculates were collected from boars of six different breeds over three years (2008–2011) and throughout the four seasons of the year identified in the northern hemisphere (winter, spring, summer and autumn). The ejaculates were cryopreserved using a standard 0.5 mL straw freezing protocol. Sperm quality was assessed before (fresh semen samples kept 24 h at 17 °C) and after freezing and thawing (at 30 and 150 min post-thawing in semen samples kept in a water bath at 37 °C), according to the percentages of total motility, as assessed by the CASA system, and viability, as assessed by flow cytometry after staining with SYBR-14, PI and PE-PNA. The data, in percentages, on sperm motility and viability after freezing and thawing were obtained at each evaluation time (recovered) and were normalized to the values before freezing (normalized). The season of ejaculate collection influenced (P < 0.01) sperm quality before freezing and after thawing (recovered and normalized), irrespective of the breed of boar. Sperm quality was lower in summer, both in terms of motility and viability, and in autumn, in terms of motility, than in winter and spring. Seasonality in the normalized data indicates that the season of ejaculate collection influences sperm freezability, regardless of the season’s influence on sperm quality before freezing. Consequently, the spermatozoa from ejaculates collected during summer and, to a lesser extent, also in autumn, are more sensitive to cryopreservation than those from ejaculates collected during winter and spring.     

Correlation between the morpho-cytohistochemistry of the outer mantle epithelium of Anodonta cygnea with seasonal variations and following pollutant exposure

Seasonal and experimental conditions induce morphological and cytochemical variations in the outer mantle epithelium (OME) of the freshwater bivalve Anodonta cygnea, probably influencing the shell calcification mechanism. In this study, OME samples were taken from untreated animals in autumn, winter, spring and summer as well as from animals exposed to divalent metals (cadmium, chromium, lead, copper and zinc) and pesticides (setoxidim and dimethoate) and observed by light microscopy. The present results showed that OME cells have larger cell volumes and increased amounts of secreted macromolecules during spring and summer than in autumn and winter. This correlates with higher shell calcification rates in spring and summer and lower shell calcification rates in autumn and winter. The experiments showed that incubation with pollutants for 8 months dramatically reduced the cellular volume so that the density of cytoplasmic material appeared higher that in the control samples. The pronounced changes in OME cells suggest a significant decrease in secretory activity following exposure to toxic agents and this has implications for the shell calcification process.     

Seasonal variability in the fertilization rate of women undergoing assisted reproduction treatments

The objective of this study was to evaluate whether seasonality affects human-assisted reproduction treatment outcomes. For this, 1932 patients undergoing intracytoplasmic sperm injection (ICSI) were assigned to a season group according to the day of oocyte retrieval: winter (n = 435), spring (n = 444), summer (n = 469) or autumn (n = 584). Analysis of variance was used to compare the ICSI outcomes. The fertilization rate was increased during the spring (winter: 67.9%, spring: 73.5%, summer: 68.7% and autumn: 69.0%; p < 0.01). In fact, a nearly 50% increase in the fertilization rate during the spring was observed (odds ratio 1.45, confidence interval 1.20-1.75; p < 0.01). The oestradiol concentration per number of oocytes was significantly higher during the spring (winter: 235.8 pg/mL, spring: 282.1 pg/mL, summer: 226.1 pg/mL and autumn: 228.7 pg/mL; p = 0.030). This study demonstrates a seasonal variability in fertilization after ICSI, where fertilization is higher during the spring than at any other time.