Prevalence and characterization of hydatidosis in Najdi sheep slaughtered in Riyadh city,Saudi Arabia

Hydatidosis is considered to be one of the important zoonotic diseases and has a significant public health importance due to the difficulties of the diagnosis. Domestic animals act as intermediate hosts and the main reservoir for the disease in humans. The main purpose of this work therefore was to determine the prevalence of hydatidosis in Najdi sheep slaughtered in Riyadh city, Saudi Arabia. Cyst location and cyst fertility and viability were also estimated, together with effect of seasons, age and sex on the prevalence of the infection. The prevalence of hydatidosis was evaluated by post-mortem examination, with intensive inspection of the visceral organs of 2785 Najdi sheep. The infection was found to prevail throughout the year in both sex, with an overall prevalence of 2.33%. The highest prevalence was recorded in winter (6.48%) while the lowest was encountered in summer (1.36%). Females were proved to be more prone to infection (70.7%) than males (29.3%). In the present study, younger sheep tended to have a higher prevalence of infection than older ones. The most commonly infected organ was the liver, with a prevalence of 81.5%. The recorded cysts showed a fertility rate of 75.4%, and a high viability rate of 61.2%. Hepatic cysts were the most fertile and viable ones (46%), while calcified cysts were not recorded during the study. Measurements of recorded cysts in all organs ranged from 2 to 6?cm in diameter.In conclusion, the high fertility and viability rate of the recorded cysts suggest that sheep are a potential source of hydatidosis transmission to dogs and the continuation of its life cycle in this region. Consequently, authorities are recommended to instigate stricter regulation of the slaughtering process, including the secure disposal of infected offal so as to minimise the transmission of cysts from slaughter houses, along with treatment of stray dogs.     

Male display rate reveals ejaculate characteristics in the Trinidadian guppy,Poecilia reticulata.

Previous work (Reynolds and Gross 1992) has demonstrated that mate choice enables female guppies, Poecilia reticulata, to obtain heritable benefits (''good genes'') for their offspring. It is not yet known whether males also signal their functional fertility, that is, their viability as fathers, to female guppies. Our study tested the hypothesis that a male''s behaviour reveals characteristics of his ejaculate. We uncovered a strong correlation between display rate and sperm number in male guppies derived from two wild Trinidadian populations. This result indicates that information on the functional fertility of potential mates is available to females. However, our investigation also found a significant relationship between the frequency of sneaky mating and sperm number. Female guppies in wild populations, particularly those experiencing a high predation regime, are constantly subjected to sneaky mating attempts. As the males responsible for these sneaky matings have highest reserves of sperm they may have the capacity to undermine female choice. The implications of these findings for sperm competition are discussed.     

不同光长诱导HPGMR过氧化物酶活性及同工酶的比较研究(简报)

湖北光敏感核不育水稻(Hubei Photo-period-Sensitive Genic Male-sterile Rice,简称HPGMR)经研究为光周期敏感的隐性雄性核不育遗传。短日照处理后用10 min红光或白光暗中断处理均起到长日不育的作用。这些特性不仅存生产上具有广泛利用的价值,而且在遗传学研究方面也具有重要的理论意义。为了探讨HPGMR的光诱导不育的机理,本文以HPGMR农垦58和正常可育农垦58(O.sativa,Japonica)为材料,对不同发育时期的幼穗和花药过氧化物酶活性及同工酶谱进行研究,试分析不同光长诱导下HPGMR过氧化物酶活性及同工酶谱的特征,结果简报如下:     

Determinants of family size in rural Glacia (Spain)

The determinants of complete family size and offspring survival were assessed by means of family reconstitution data from a 19th & 20th century rural population of Northwest Spain. The reproductive performances of families were submitted to a stepwise regression analysis in which the number of children born alive and those surviving to reproductive age per family were taken as dependent variables, while 13 other variables were defined as independent. Infant mortality appears to explain most fertility variation; an earlier marital age and at first maternity leads to an increased family size. Survival seems to be the result of the apposite interaction of both fertility and mortality in early childhood.     

A field study of the fertility of transported equine semen

A field trial of artificial insemination in horses with transproted, chilled semen was conducted using a specially designed container which permitted a controlled, slow initial rate of cooling (-0.3 degrees C/min) and maintenance of a final temperature of 4 degrees -6 degrees C for more than 36 hrs. Forty-six mares in 23 states were inseminated with semen from three German Warmblood stallions standing at stud in Hamilton, Massachusetts. A third-cycle conception rate of 91% was obtained.     

Effects of cold shock and phospholipase A2 on intact boar spermatozoa and sperm head plasma membranes

Head plasma membranes (HPM) isolated from cryopreserved boar spermatozoa show an excessive fluidization, which might be involved in the loss of fertility. The current study assessed the ability of cold shock (5 degrees C) and phospholipase A2 (PA2) to duplicate these effects on membrane structure and to affect 45Ca2+ uptake and gross morphological characteristics of whole, fresh boar-sperm. The HPM from cold-shocked sperm showed a significantly greater rate of fluidization over time than did HPM from control sperm. Addition of PA2 (bee or snake venom, 0.1 or 10.0 ng/ml) to HPM from control sperm caused fluidization similar to cold shocking, but to a lesser degree (P less than 0.05). Cold-shocked intact sperm exhibited severe acrosomal disruption, loss of motility, and increased 45Ca2+ uptake relative to control sperm. Addition of PA2 (bee or snake venom, 0.1, 1.0., 10.0, and 1,000 ng/ml) to control sperm had no effect on gross morphology or motility while maintaining or increasing sperm extrusion of 45Ca2+. Therefore, although PA2 can, to some extent, duplicate the effects of cold shock on HPM molecular organization, its lipid hydrolytic action is insufficient to cause all the gross disruptions of severe thermal shock. Both PA2 and cold shock disrupted HPM structure, but only cold shock increased 45Ca2+ uptake, suggesting that cold shock may be increasing 45Ca2+ uptake in areas other than the head. Cold shock disrupts sperm on three levels; membrane molecular organization, intracellular Ca2+ regulation, and gross morphology/motility.     

Above‐ground biomass distribution among species during early old‐field succession

Abstract. The interdependence of species richness and plant biomass has widely been accepted as a general biodiversity rule. However, there is no information about how relationships are established during colonization and how total biomass is distributed among plants. The main objective of this study was to determine the role of several factors which we have hypothetized as affecting biomass distribution among species in an early old‐field community. To test this hypothesis, we conducted an experiment in a deeply ploughed Agropyro‐Rumicion crispi community in the Basque Country (Spain). Light, water and soil nitrogen content were factorially manipulated resulting in eight experimental treatments. We also examined several site features, which could potentially influence final biomass distribution: seed bank composition, soil physico‐chemical heterogeneity and cover and density of the dominant plant species in the community. A partition hypothesis testing approach using Redundancy Analysis was conducted to determine the fraction of biomass distribution variability assigned to each treatment and site feature. The most important species, in terms of biomass, were Agropyron repens, Sinapis arvensis, Arrhenatherum bulbosum and Picris echioides. As a general conclusion, biomass distribution among species during early secondary succession primarily depends on light availability and nitrogen supply. Several soil variables, such as magnesium, calcium and clay contents, also explain a relevant fraction of the biomass distribution among plant species. On the contrary, we found no effect of seed bank composition on biomass distribution. Finally, the total species number and cover of dominant species such as Sinapis arvensis, may determine final biomass distribution.     

Phytometric estimation of fertility of waterlogged rich-fen peats usingEpilobium hirsutum L.

Summary The above-ground net production of herbaceous vegetation in 16 stands of waterlogged rich fen in Broadland, Norfolk UK, has been compared with the growth ofEpilobium hirsutum seedlings (in controlled environment) on replicate peat samples from each site and with the chemical composition of extracts from sub-samples of each peat (Ca, Mg, Na, K, Fe, Mn, inorganic P, inorganic N). There were no consistent or significant relationships between measured concentrations of major nutrients (K, N, P) in peat samples and netin situ production of the vegetation or with growth ofE. hirsutum seedlings on each peat. There was a strong, significant (p<0.001) relationship between above ground productionin situ and growth ofE. hirsutum seedlings. Seedling growth thus provided a simple, sensitive phytometric measure of fertility of the waterlogged peats (pH range 6.0–7.0). One possible limitation is the apparent sensitivity ofE. hirsutum seedlings to high manganese concentrations.     

The reporductive cycle and population dynamics: The case of the Banges Valley (Valais,Switzerland) in the XIXth century

By discussing the concept of population reproduction from the points of view of different disciplines, we propose here a reflection on the foundation of population studies, i.e. the definition of the population studied and the mechanisms of its dynamics. Our considerations are based on the example of the Bagnes valley in the 19th century, putting it into perspective with data we have gathered in two other traditional populations. In the first part of the paper, we explore the different types of constraints and facilitators which act on the effective descent of individuals. The population reproduction is thus considered in terms of numerical replacement, that is to say the meaning which demography usually gives to it. The second part focuses on the factors of the renewal of the group, signification attributed to population reproduction in evolutionary sciences. The definition of the boundaries of the population and their tendencies become central, as well as the criteria following which individuals belong to the group. Translation from the French by Graham Grayston     

Nutrient accumulation byPinus caribaea in its native savanna habitat

Summary Concentrations of P, N, K, Ca, and Mg in above-ground tissues ofP. caribaea were sampled in the species'native savanna habitat. Concentrations were relatively low, but some evidence of higher consumption of K and Ca was found in trees grown on more fertile soils. Regressions were developed to predict the quantities of nutrients sequestered in above-ground tree tissues, and estimates made of the quantities stored in above-ground stands of this species in its native habitat and in several plantations elsewhere. Estimates were also made of the nutrient removals to be expected by harvesting these stands in different ways. Nutrient quantities stored in stands generally exceed those extractable from savanna surface soils, and it is suggested that inputs from the atmosphere are the most probable alternate nutrient source. A comparison of these inputs for tropical areas with the quantities required for stand growth in the savanna, and harvesting removals, suggests that an adequate supply of all elements except P exists, provided that capture by pine is effective. However, atmospheric inputs generally fall below the storage and harvest removal rates for fast growing exotic plantations of this species suggesting that multiple rotations of these plantations at current growth rates may not be feasible without artifical fertilization.