THE SEX SYSTEM OF THE POPULATION OF SAGITTARIA SAITTIFOLIA AS AN INDICATOR OF THE ECOLOGICAL STATUS OF A RIVER

The ecological state of small rivers that define the water regime of the territory, as well as the water supply of larger rivers, the quality of their waters is a matter of a serious concern. The ecosystems of watercourses in urban areas exposed to pollution by industrial and domestic wastes are under the maximum anthropogenic load. Bioindicative methods, which let to assess directly the status of aquatic ecosystems and their individual components, occupy an important place in the system of ecological monitoring of water bodies. Plants respond to toxicants in an aquatic habitat by the abnormality of biosynthesis of chlorophyll, carotenoids and other pigments, change of mineral balance, phytohormones, which leads to a change in their reproductive differentiation. In this regard, water quality assessment was carried out on the basis of chemical analysis and bioindication concerning Sagittaria sagittifolia populations in the upper and middle stream ways of the river Tyosha flowing through the Nizhny Novgorod region. The article presents the results of some organoleptic and chemical parameters such as pH level of overall hardness, concentration of nitrates and nitrites, ions of ammonium, phosphates, mercury, concentration of oxygen and carbon dioxide in the water. It was detected that there were exceeding quantities of ammonium ions, nitrite ions, phosphates in the water of all ranges of the river Tyosha, and also high content of iron in the downstreams of the river. The findings suggest that the reproductive structure of arrowhead inflorescences can serve as a bio-indicator of the degree of water pollution. The harder the environmental conditions of the plant habitat in the water body, the more intensive is a shift in the ratio of flowers to the feminine side. It has been shown that due to the deterioration of environmental conditions, the number of compound inflorescences of the arrowhead and the numbers of whorls in them decrease and, on the other hand, there is an increase in the percentage of plants with simple typical inflorescences. A credible shift in the reproductive ratio of arrowhead inflorescences to the female side is spotted on the downstream river station near Lukoyanov and industrial community Shatky, where the complex of environmental factors for its growth is the least favorable. It was established that anthropogenic pollution of the river has a negative effect on the reproductive sphere of Sagittaria sagittifolia, causing a reduction in pollen fertility, which is confirmed by the chemical analysis of water. On the basis of the studies the assessment of the ecological status of the water in the Tyosha river was given.

Geometry shapes evolution of early multicellularity

Organisms have increased in complexity through a series of major evolutionary transitions, in which formerly autonomous entities become parts of a novel higher-level entity. One intriguing feature of the higher-level entity after some major transitions is a division of reproductive labor among its lower-level units. Although it can have clear benefits once established, it is unknown how such reproductive division of labor originates. We consider a recent evolution experiment on the yeast Saccharomyces cerevisiae as a unique platform to address the issue of reproductive differentiation during an evolutionary transition in individuality. In the experiment, independent yeast lineages evolved a multicellular “snowflake-like” cluster form in response to gravity selection. Shortly after the evolution of clusters, the yeast evolved higher rates of cell death. While cell death enables clusters to split apart and form new groups, it also reduces their performance in the face of gravity selection. To understand the selective value of increased cell death, we create a mathematical model of the cellular arrangement within snowflake yeast clusters. The model reveals that the mechanism of cell death and the geometry of the snowflake interact in complex, evolutionarily important ways. We find that the organization of snowflake yeast imposes powerful limitations on the available space for new cell growth. By dying more frequently, cells in clusters avoid encountering space limitations, and, paradoxically, reach higher numbers. In addition, selection for particular group sizes can explain the increased rate of apoptosis both in terms of total cell number and total numbers of collectives. Thus, by considering the geometry of a primitive multicellular organism we can gain insight into the initial emergence of reproductive division of labor during an evolutionary transition in individuality.

Studies of the Effects of Neonatal Exposure to Genistein on the Developing Female Reproductive System

Studies have shown that developmental exposure to genistein alters murine reproductive differentiation, resulting in abnormal ovarian development (multioocyte follicles) and uterine neoplasia later in life. Further, reproductive function was altered. Prolonged estrous cyclicity was observed following neonatal genistein treatment (0.550 mg/kg) on Days 15 with doseand age-related increase in severity. Fertility, determined at 2, 4, and 6 months, showed decreased numbers of genistein-treated females (0.5 or 5 mg/kg) delivering live pups and reduced numbers of pups. At 6 months, 60% of 0.5 mg/kg and 40% of 5 mg/kg groups delivered live pups compared to 100% of controls. At 2 months, half the mice treated with 25 mg/kg of genistein and none treated with 50 mg/kg delivered live pups, although half of the latter group showed signs of pregnancy with few small implantation sites. Ovarian function was disrupted in the low genistein-dosed mice with increased numbers of corpora lutea (CLs) compared to controls and increased ovulated oocytes following exogenous gonadotropins treatment. In contrast, mice treated with high genistein doses had decreased numbers of CLs; ovulation could be restored with exogenous gonadotropins. Thus, neonatal treatment with genistein at environmentally relevant doses caused adverse consequences on ovarian development and reproductive function.

Latitudinal variation in the sociality of allodapine bees (Hymenoptera: Apidae): sex ratios, relatedness and reproductive differentiation

Variation in sociality of two Australian allodapine bees was investigated over a latitudinal range of 10˚, spanning subtropical to cool temperate forests in eastern Australia. Exoneura robusta is univoltine and singly brooded in southern populations but is able to produce two broods per season in northern populations, leading to opportunities for sib rearing by older brood members. In contrast, sympatric colonies of E. angophorae show no such variation with latitude, and all populations exhibit some colonies where opportunities for sib rearing arise. Patterns of ovarian differentiation, relatedness and sex allocation were examined over a one-year period for these two sympatric species in four populations. Within each species, the timing of ovarian development and the degree of reproductive skew were similar at all sites, but the onset of egg-laying and brood development was earlier in E. angophorae than in E. robusta. Relatedness and sex allocation patterns in northern populations of these species were not markedly different from southern populations. Selection for female-biased sex allocation and high reproductive skew in Exoneura probably stems from strong benefits from cooperative nesting, and our results suggest that opportunities for sib rearing (and eusociality) in these species may depend on latitudinally mediated brood development rates, and are unrelated to levels of sex bias and relatedness.