A seasonal periodicity in relapses of multiple sclerosis? A single-center,population-based,preliminary study conducted in Bologna,Italy

Background  

Temporal, i.e., 24-hour, weekly, and seasonal patterns in the occurrence of acute cardiovascular and cerebrovascular events are well documented; however, little is known about temporal, especially seasonal, variation in multiple sclerosis (MS) and its relapses. This study investigated, by means of a validated chronobiological method, whether severe relapses of MS, ones requiring medical specialty consultation, display seasonal differences, and whether they are linked with seasonal differences in local meteorological variables.     

西双版纳热带季节雨林的研究

本文以多个样方的资料分析,从群落综合特征上研究了西双版纳热带季节雨林的特点和类型、物种组成、生活型谱、叶级谱等。根据上层标志树种、群落生态外貌特征和生境把西双版纳的热带季节雨林区分为低丘雨林和沟谷雨林二个群系组,各包括若干群系。低丘雨林中面积最大和最有代表性的群系是大药树、龙果林,而沟谷雨林中最有代表性的群系是番龙眼、千果榄仁林。二者相比,低丘雨林的物种多样性要小一些,附生植物相对少一些,小、矮高位芽植物和小叶、落叶树种比例稍高,在生态上向季雨林和热带山地的常绿阔叶林过渡,有更强的地方代表性。沟谷雨林则更接近典型的湿热带雨林。     

Prey behavior, age-dependent vulnerability, and predation rates

Variation in the temporal pattern of vulnerability can provide important insights into predator-prey relationships and the evolution of antipredator behavior. We illustrate these points with a system that has coyotes (Canis latrans) as a predator and two species of congeneric deer (Odocoileus spp.) as prey. The deer employ different antipredator tactics (aggressive defense vs. flight) that result in contrasting patterns of age-dependent vulnerability in their probability of being captured when encountered by coyotes. We use long-term survival data and a simple mathematical model to show that (1) species differences in age-dependent vulnerability are reflected in seasonal predation rates and (2) seasonal variation in prey vulnerability and predator hunt activity, which can be associated with the availability of alternative prey, interact to shape seasonal and annual predation rates for each prey species. Shifting hunt activity from summer to winter, or vice versa, alleviated annual mortality on one species and focused it on the other. Our results indicate that seasonal variation in prey vulnerability and hunt activity interact to influence the impact that a predator has on any particular type of prey. Furthermore, these results indicate that seasonal variation in predation pressure is an important selection pressure shaping prey defenses.     

Seasonal cycles in the blood plasma concentration of FSH, inhibin and testosterone, and testicular size in rams of wild, feral and domesticated breeds of sheep

Seasonal cycles in testicular activity in rams were monitored in groups of wild (mouflon), feral (Soay) and domesticated breeds of sheep (Shetland, Blackface, Herdwick, Norfolk, Wiltshire, Portland and Merino) living outdoors near Edinburgh (56 degrees N). The changes in the blood plasma concentrations of FSH, inhibin and testosterone, and the diameter of the testis were measured every half calendar month from 1 to 3 years of age. There were significant differences between breeds in the magnitude and timing of the seasonal reproductive cycle. In the mouflon rams, the seasonal changes were very pronounced with a 6-15-fold increase in the plasma concentrations of FSH, inhibin and testosterone from summer to autumn, and a late peak in testicular diameter in October. In the Soay rams and most of the domesticated breeds, the seasonal increase in the reproductive hormones occurred 1-2 months earlier with the peak in testicular size in September or October. In the two southern breeds (Portland and Merino), the early onset of testicular activity was more extreme with the seasonal maximum in August. In cross-bred rams, produced by mating Soay ewes (highly seasonal breed) with Portland or Merino rams (less seasonal breeds), there was a seasonal reproductive cycle that was intermediate compared to that of the parents. A comparison between all 11 breeds showed a significant correlation between the timing of the seasonal cycle in plasma FSH concentration and testicular diameter (time of peak FSH vs testis, r = 0.95). The overall results in the rams are consistent with a primary role of FSH in dictating the seasonal cycle in testicular size and the secretion of inhibin. The earlier seasonal onset in the testicular cycle in the southern breeds of domesticated sheep, and the differences from the wild type, are taken to represent the effects of genetic selection for a longer mating season.     

Leptin, a neuroendocrine mediator of immune responses, inflammation, and sickness behaviors

This article is part of a Special Issue "Neuroendocrine-Immune Axis in Health and Disease." Effective immune responses are coordinated by interactions among the nervous, endocrine, and immune systems. Mounting immune, inflammatory, and sickness responses requires substantial energetic investments, and as such, an organism may need to balance energy allocation to these processes with the energetic demands of other competing physiological systems. The metabolic hormone leptin appears to be mediating trade-offs between the immune system and other physiological systems through its actions on immune cells and the brain. Here we review the evidence in both mammalian and non-mammalian vertebrates that suggests leptin is involved in regulating immune responses, inflammation, and sickness behaviors. Leptin has also been implicated in the regulation of seasonal immune responses, including sickness; however, the precise physiological mechanisms remain unclear. Thus, we discuss recent data in support of leptin as a mediator of seasonal sickness responses and provide a theoretical model that outlines how seasonal cues, leptin, and proinflammatory cytokines may interact to coordinate seasonal immune and sickness responses.     

Renewal of genetic composition of a lancelet, Branchiostoma belcheri, in the Seto Inland Sea, Japan

We studied renewal of genetic composition of a lancelet, Branchiostoma belcheri, at a station in the Seto Inland Sea, Japan, using random amplified polymorphic DNA (RAPD) technique. We detected a total of 49 DNA bands from 27 individuals of 5 seasonal samples. Among these, some were specific to individual or seasonal sample. There were no bands common to all individuals. We calculated the Band Sharing Index (BSI) values for each combination of individuals. BSI was in a wide range of 0.00-0.97 and the average BSI between the individuals of a sample was remarkably different from sample to sample (0.37-0.83). In cluster analysis on the basis of BSI, largely 3 clusters were constructed, which finally connected to a single cluster at as low as about 0.2 of BSI. Besides, many clusters were constructed exclusively by a seasonal sample. These results suggest a large gene pool of lancelets in this area, the remarkable differences in gene pool size among the samples and a seasonal renewal of genetic composition at a habitat.     

Carbon,Nitrogen, Phosphorus,and Potassium Stoichiometry in an Ombrotrophic Peatland Reflects Plant Functional Type

Ombrotrophic bog peatlands are nutrient-deficient systems and important carbon (C) sinks yet the stoichiometry of nitrogen (N), phosphorus (P) and potassium (K), essential for plant growth and decomposition, has rarely been studied. We investigated the seasonal variation in C, N, P, and K concentrations and their stoichiometric ratios in photosynthetically active tissues of 14 species belonging to five plant functional types (PFTs) (mosses, deciduous trees/shrubs, evergreen shrubs, graminoids, and forb) at Mer Bleue bog, an ombrotrophic peatland in eastern Ontario, Canada. Although we observed variations in stoichiometry among PFTs at peak growing season, there was convergence of C:N:P:K to an average mass ratio of 445:14:1:9, indicating N and P co-limitation. Nitrogen, P, and K concentrations and stoichiometric ratios showed little seasonal variation in mosses, evergreens, and graminoids, but in forb and deciduous species were the largest in spring and decreased throughout the growing season. Variations in nutrient concentrations and stoichiometric ratios among PFTs were greater than seasonal variation within PFTs. Plants exhibit N and P co-limitation and adapt to extremely low nutrient availability by maintaining small nutrient concentrations in photosynthetically active tissues, especially for evergreen shrubs and Sphagnum mosses. Despite strong seasonal variations in nutrient availabilities, few species show strong seasonal variation in nutrient concentrations, suggesting a strong stoichiometric homeostasis at Mer Bleue bog.     

Seasonal changes in the concentrations of Ca,Fe, K,Mg, Mn and Na in eelgrass (Zostera marina L.) in the Limfjord,Denmark

The seasonal changes in concentrations of calcium, iron, potassium, magnesium, manganese and sodium in above- and below-ground parts of eelgrass (Zostera marina L.) were studied at three locations in the Limfjord, Denmark.The concentrations of calcium, iron and manganese in eelgrass differed significantly at the three stations. Above-ground parts of eelgrass contained significantly higher concentrations of potassium and manganese than below-ground parts, whereas the concentrations of iron and sodium were highest in the below-ground parts. Calcium and mangnesium concentrations in the two fractions were not significantly different.Significant seasonal variations were observed in the concentrations of calcium, potassium, manganese and sodium in above-ground parts of eelgrass and in the concentrations of iron, magnesium and sodium in below-ground parts. Iron, potassium, manganese and, to an extent, sodium showed a similar seasonal pattern with maximum concentrations in the summer and minimum concentrations in the spring or fall, whereas calcium concentrations in the above-ground parts showed the opposite pattern.The observed seasonal variation patterns are discussed in relation to the respective metals and changes in environmental factors.     

Seasonal Variations in Atmospheric Pressure,Partial Oxygen Density,and Geomagnetic Activity as Additional Synchronizers of Circannual Rhythms

Biophysics - Abstract—The seasonal dynamics of atmospheric pressure and geomagnetic activity in the regions with different climates were analyzed to calculate the seasonal variations in the...     

Spontaneous gallstone formation in deer mice: interaction of cholesterol,bile acids,and dietary fiber

A study of the physiologic and ecologic factors involved in a spontaneous seasonal gallstone cycle of deer mice (Peromyscus maniculatus gambelii) was conducted at the Tulelake National Wildlife Refuge (California, USA) from March 1991 to June 1992. The specific hypothesis examined was whether or not seasonal increases in dietary fiber intake provides the necessary conditions for a solubility defect, or supersaturation mechanism, resulting in precipitation of cholesterol gallstones. Results indicated that in addition to the seasonal gallstone prevalence cycle, these deer mice exhibit significant seasonal cycling in serum cholesterol, serum bile acids, fecal bile acids, and diet composition. These physiologic and dietary cycles were phase-advanced 3 mo over the gallstone prevalence cycle, indicating an approximate 3 mo time period for gallstone formation under field conditions. Further, seasonal dietary fiber (plant material and seeds) was positively correlated with both serum cholesterol and the fecal bile acids. This suggests that in wild deer mice, variations in dietary fiber may significantly affect the resorption of bile acids, thereby providing a potential physiologic and nutritional mechanism for spontaneous cholesterol gallstone formation.     

Seasonal variation of livebirths, stillbirths, extramarital births and twin maternities in Switzerland.

A study was made of the seasonal variation in all births, and births according to marital status, multiplicity and birth status (live and still) in Switzerland recorded between 1876 and 1990. To obtain seasonal variation in as pure as possible form, our analyses are based on rates. When comparing the seasonality in data sets showing markedly different levels, standardised indices were used. Assuming the length of pregnancies with twins to be about one month shorter than for pregnancies with singletons, lagged twinning rates were calculated but, in comparison with actual twinning rates, the general seasonal variation remained. Therefore, this study was based on actual twinning rates. A monotonic increase in the amplitude of the seasonal variation in general births was noted for the period 1876-1930, with strong seasonal variation holding for 1921-1980. After that, a marked decline in the amplitude can be observed. Seasonality of both all births and twin maternities showed very similar pattern for the periods 1876-1930 and 1969-1990, with maxima in the spring (March-May) and troughs in late autumn (October-December). Twin maternities showed a strong seasonality for the period 1876-1930, being about 20% higher in March than in October. The twinning rate in the period 1876-1930 was about 2.6 per thousand units higher than in the period 1969-90. For twin maternities there was also a stronger seasonal variation during the earlier period than during the later one. The pattern of the seasonal variation for extramarital births, showing a maximum in February (conceptions in May-June) and a minimum in August (conceptions in November-December) with a difference of no less than 24% was more marked than for the marital births. It seems likely that this seasonality of extra-marital maternities was due mainly to seasonal variation of coital rates and multiple ovulation in the early summer months coinciding with optima of light, temperature and food supply. A strong reduction in the rate of stillbirths (gestational age more than 29 weeks) was observed during the twentieth century. The stillbirth rate declined from about 40 per 1000 in the 1870s to fewer than 5 per 1000 in the 1980s. Irrespective of this strong decline in the stillbirth rate, the same seasonal rhythm was noticed throughout the period with high stillbirth rates among births around March and low rates during the summer and autumn.     

Correlation with changes in horns and pelage, but not reproduction, of seasonal cycles in the secretion of prolactin in rams of wild, feral and domesticated breeds of sheep

Seasonal cycles were monitored in groups of wild (mouflon), feral (Soay) and domesticated breeds of sheep (Shetland, Blackface, Herdwick, Norfolk, Wiltshire, Portland, Merino, Soay x Portland and Soay x Merino) living outdoors near Edinburgh (56 degrees N). Changes in the blood plasma concentrations of prolactin and FSH, and growth of the horns and pelage were measured every half calendar month from 1 to 3 years of age. In all breeds there was a clearly defined seasonal cycle in the plasma concentration of prolactin with an 18-66-fold increase in mean values from the nadir in November and December to the peak in May and June. The seasonal increase in prolactin was closely correlated with the seasonal increase in the growth of the horns, both within and between breeds (e.g. time of peak prolactin vs horn growth for 11 breeds, R = 0.62, P less than 0.05). In the mouflon, Soay and some of the domesticated breeds of sheep (Wiltshire, Herdwick and Shetland), the seasonal increase in prolactin was also temporally correlated with the resurgence of growth of the pelage in spring and a conspicuous moult. In the other breeds developed to produce fine wool (e.g. Norfolk, Portland and Merino), there was no clear seasonal change in the pelage and growth continued throughout the year. Comparison between breeds indicated that continuous growth of the pelage was associated with higher plasma prolactin concentrations in winter. The times of the seasonal changes in plasma concentrations of prolactin were not significantly correlated with the corresponding changes in the plasma concentrations of FSH. The overall results are consistent with a role for prolactin related to the growth of the horns and pelage rather than the seasonal cycle in reproduction. The differences between the wild-type and the domesticated breeds in the pelage represent the effect of selective breeding to produce a long fine fleece which has involved changes in both the seasonal pattern of prolactin secretion and the growth characteristics of the hair fibres.     

Episodic herbivory,plant density dependence,and stimulation of aboveground plant production

Herbivory is a major energy transfer within ecosystems; an open question is under what circumstances it can stimulate aboveground seasonal primary production. Despite multiple field demonstrations, past theory considered herbivory as a continuous process and found stimulation of seasonal production to be unlikely. Here, we report a new theoretical model that explores the consequences of discrete herbivory events, or episodes, separated in time. We discovered that negative density (biomass) dependence of plant growth, such as might be expected from resource limitation of plant growth, favors stimulation of seasonal production by infrequent herbivory events under a wide range of herbivory intensities and maximum plant relative growth rates. Results converge to those of previous models under repeated, short‐interval herbivory, which generally reduces seasonal production. Model parameters were estimated with new and previous data from the Serengeti ecosystem. Patterns of observed frequent and large magnitude stimulated production in these data agreed generally with those predicted by the episodic herbivory model. The model thus may provide a new framework for evaluating the sustainability and impact of herbivory.     

Temporal, seasonal, and regional differences in births and deaths in Aland (Finland)

A good knowledge of the seasonal variation during normal years is of fundamental importance for analyses of the effects of wars, famines, epidemics, or similar privations on births and deaths. In this study we consider data from the Aland Islands (Finland) for 1650-1950. During the period 1650-1793 there are subperiods with missing data for all parishes, and consequently the total data for the Aland Islands for this period have to be estimated using available data. For the period 1794-1950 the registered data seem to be complete and reliable, but the war year 1809 shows a marked deficit of births. During the last decades of the 19th century the number of births increases markedly and after that shows a strong decrease. After the 1930s births increase again. To allow seasonality comparisons between the Aland Islands as a whole and its subregions, we base our studies on seasonal indexes. There is a markedly decreasing temporal trend in the seasonal variation of births for the Aland Islands as a whole, but the general pattern remains mainly the same, having two peaks, one in March-April and one in September-October. For the period 1901-1950 the seasonal variation almost disappeared. The strength of the seasonal variation in births shows regional differences, but the general pattern is mainly the same. The outermost parish, K?kar, an isolate of its own, shows the strongest seasonal variation in births. The annual number of deaths shows some marked peaks, especially in the war year 1809. For both sexes there are marked peaks in 1809, indicating that the deaths were mainly caused by epidemic diseases rather than by killing in battles. For mortality a decreasing trend in the seasonal variation is observed during 1650-1750, but after 1751-1800 the strength of seasonality shows an increasing trend and a sinusoidal pattern.     

西双版纳热带季节雨林与橡胶林土壤呼吸

季节雨林和橡胶(Hevea brasiliensis)林是西双版纳热带森林生态系统中原始林和大面积种植人工林的两种代表类型。热带季节雨林层次结构复杂,多样性丰富,而橡胶林结构简单,乔木层只有橡胶树1种。应用碱吸收法,研究了这两种植被类型土壤呼吸速率、地下5 cm土壤温度、气温和土壤含水率的季节变化规律,以及土壤呼吸速率与地下5 cm土壤温度、气温和土壤含水率的关系。结果表明:1)季节雨林和橡胶林土壤呼吸速率、土壤温度、气温和土壤含水率都有明显的季节变化,而且两种林型的变化趋势基本一致;2)季节雨林和橡胶林土壤呼吸速率与地下5 cm土壤温度和气温之间具有显著的指数相关关系,显著水平达1%,与地下5 cm温度的相关性(r²分别为0.87和0.82)明显高于与气温的相关性(r²分别是0.80和0.72);3)季节雨林和橡胶林土壤呼吸速率与土壤含水率具有显著的线性相关(r²分别是0.73和0.63),显著水平达1%;4)橡胶林的土壤呼吸速率明显高于季节雨林,这与两种林型的结构有关;5)季节雨林和橡胶林土壤呼吸的Q₁₀分别为2.16和2.18,比文献报道的热带土壤的Q₁₀(1.96)稍高。     

The seasonal factors influencing child malnutrition on the Nembi Plateau,Papua New Guinea

A sample of children from the Nembi Plateau, Papua New Guinea, is monitored for nutritional status, episodes of sickness and disease, diets, work activity of mothers, and weight changes; and health and census records are examined for seasonal patterns of disease, deaths, birth, and birth weights. A seasonal pattern in birth weight reinforced by a seasonal pattern in growth performance and compounded by a seasonal pattern of disease suggests that the time of year in which a child is born is important to the child's growth and health. Yields, labor, and ritual surrounding the gardens give rise to the seasonal pattern of events that impinge upon the health of children.     

Notes on important algal herbaria,V

The seasonal succession of algal species in the epipelon of two small pools over a period of three years is described in relation to changes in silica, nitrate-nitrogen and phosphate-phosphorus concentrations in the water above the sediments. Recurring patterns of seasonal growth of the various species are discussed.     

北京小龙门森林生态系统定位站土壤螨类的垂直分布和季节变动

通过对小龙门森林生态系统定位站栎树林中所设立的5个土壤动物采样点,进行每月1次的土壤取样调查(从1993年4月到1994年1月),,对各土层中螨类的垂直分布和季节变动进行调查分析、结果显示土壤螨类无论是个体数量还是相对丰度,都具有明显的表聚性特点,85％的土壤螨类皆出现于枯枝落叶层和0～5cm的土层。土壤螨类的季节变动调查显示,在枯枝落叶层,土壤螨类有显著的季节变动,且高峰值出现在1993年10月,在10～15cm的土层中,土壤螨类也有相对显著的季节变动,但它的高峰值出现在1994年1月,而在0～5cm和5～10cm的2个土层中,土壤螨类的数量在各个月份之间没有显著的差异。     

Pandemic Influenza H1N1 2009, Innate Immunity,and the Impact of Immunosenescence on Influenza Vaccine

Seasonal and pandemic strains of influenza have widespread implications for the global economy and global health. This has been highlighted recently as the epidemiologic characteristics for hospitalization and mortality for pandemic influenza H1N1 2009 are now emerging. While treatment with neuraminidase inhibitors are effective for seasonal and pandemic influenza, prevention of morbidity and mortality through effective vaccines requires a rigorous process of research and development. Vulnerable populations such as older adults (i.e., > age 65 years) suffer the greatest impact from seasonal influenza yet do not have a consistent seroprotective response to seasonal influenza vaccines due to a combination of factors. This short narrative review will highlight the emerging epidemiologic characteristics of pandemic H1N1 2009 and focus on immunosenescence, innate immune system responses to influenza virus infection and vaccination, and influenza vaccine responsiveness as it relates to seasonal and H1N1 pandemic influenza vaccines.     

Mate preference in males of the cabbage butterfly, Pieris rapae crucivora, changes seasonally with the change in female UV color

We initially investigated whether females of the cabbage butterfly, Pieris rapae crucivora, exhibit a seasonal change in ultraviolet wing color, which is a key stimulus for mate recognition by conspecific males, and whether and how a seasonal change affects the mating behavior of the males. We found that female UV wing color changes seasonally, the color being more pronounced in summer than in spring or autumn. We also demonstrated that male mate preference changes seasonally, concomitantly with the change in female UV color. Specifically, males appearing in summer exhibit a mating preference for summer-form females over spring- or autumn-form females, while those appearing in spring or autumn exhibit no seasonal preference, thereby facilitating more effective mate location. Our results suggest that this field of study will require more strictly controlled experimental investigation in which the seasonal change in UV color is considered when UV-influenced mating behaviors such as mate choice are investigated.