Cytogenetic characteristics of seed offspring of leafy tree plants from one-kilometer zone of Novovoronezh nuclear power station

Cytogenetic characteristics (mitotic activity, level and spectrum of pathological mitoses, nucleoly characteristics) of seed offspring of Quercus robur L. and Betula pendula Roth from Novovoronezh nuclear power station's 1-kilometer zone have been studied. It has been shown the change of time of passing though mitotic stages by cells, the increasing of bridges frequency occur in spectrum of mitotic aberrations (that shows activation of reparation systems), the change in nucleoly characteristics (the part of polynucleolaris cells increase in case of oak and decrease in case of birch, the rase of surface square of single nucleolies). The phenomena, mean above, probably, induced by synergic effects of Novovoronezh nuclear power station and environment pollutants. The most contaminated territories of 1-kilometer zone of Novovoronezh nuclear power station have been discovered by means of methods of cluster analysis of total cytogenetic characteristics of tree plants seed offspring.     

The kinetics of mycelial growth.

Based on the assumption that mycelial growth follows the logistic growth law, formulae have been developed to express the growth of fungal colonies under a variety of geometric constraints. Analysis was done of Deppe's (1973) results on surface colony growth, where the mass of the colony grew exponentially during most colonial growth, and of Trinci's (1970) results on submerged "pellet" growth, where the mass of the colony increased as the cube of time during most colony growth. In both cases, the linear dimensions of the colony were increasing linearly while the mass was changing in these quantitatively different manners. It is concluded that these disparate growth behaviours result from different habits of growth; in two-dimensional colony growth a new region of space if invaded by an amount of mycelium small in proportion to the final "carrying capacity" of the region, and in three-dimensional colony growth a region is invaded with an amount of mycelium almost equal to the region's final limiting mycelial mass. Thus, the types of growth law for colony mass which are applicable for a particular organism in a particular physical environment depend critically on the degree to which the invading hyphae initially occupy the space.     

The role of motivation in the performance of a conditioned switching-over of the maze habit in ants Myrmica rubra after a change in the quality of the food reinforcement

Active foragers Myrmica rubra were trained in a maze under conditions of different levels of colony need in food with carbohydrate (sugar syrup) or protein (ants Lasius niger pupae) reinforcement. Acquisition of the maze habit was better under conditions of reinforcement with pupae, especially by its time indices. Ants were able to modify the acquired habit when the reinforcement quality was changed. It was shown that learning was possible only when the colony and after a change pupae for the syrup was "hungry". Under these conditions, after a change of the syrup for pupae or visa versa the previously acquired optimum habit was transferred. Several hours later, with satiation of the colony, food reactions learned with protein reinforcement switched-over to "stochastic" non-optimized behavior with the dominance of exploratory reactions. Thus, it was shown that higher social insects ants were capable for conditioned switching-over. Different forms of this phenomenon depended on the level of the colony need in food and, consequently, on the level of the social food motivation of foragers ants.     

Studies on the Control of Mitotic Activity in Excised Roots : I. The Experimental System

The mitotic characteristics of excised roots of the garden pea, Pisum sativum, have been studied under conditions of controlled nutrition. The excised root system was tested with regard to its ability to respond, mitotically, to various carbon sources. Sucrose, glucose, fructose, and DL-glyceraldehyde were found to support mitotic activity in excised roots, galactose and 2-deoxy-D-glucose were toxic, and mannose ineffective. Initiation of mitotic activity in the presence of glucose was inhibited by the respiratory poisons, KCN and malonic acid, the uncoupling agent, 2,4-dinitrophenol, but was not notably affected by the protein synthesis inhibitor, chloramphenicol. The glucose-induced response in mitotic activity was not affected by the carcinogen, urethan, and indeed, there is some evidence that the response was actually enhanced. The fact that KCN, malonic acid, and probably 2,4-dinitrophenol, in suitable concentrations inhibit the onset of cell division suggests that some level of operation of the Krebs'' cycle is essential for commission of cells into mitosis. Likewise, failure to inhibit cells in the process of active mitosis by KCN and malonic acid is not inconsistent with the idea that there is a shift from reliance on aerobic to anaerobic respiration between antephase and active mitosis.     

Tradescantia Bioassays as Monitoring Systems for Environmental Mutagenesis: A Review

Since the early studies on the genetic effects of chemical and physical agents, species and clones of Tradescantia have been used as experimental subjects, by virtue of a series of favorable genetic characteristics. Bearing just six pairs (2n = 12) of large, easily observable chromosomes, cells from almost every part of the plant, from the root tips to the developing pollen tube, yield excellent material for cytogenetic studies.

As a consequence of the intensive use of Tradescantia in genetic studies, a series of genetic characteristics have been found that offer opportunities for the detection of agents affecting the stability of the genome. At least five such characteristics have been selected as endpoints for the establishment of assays to evaluate mutagenesis. Three of these, root-tip mitosis, pollen-tube, and microspore mitosis are essentially chromosome aberration assays, wherein one observes and evaluates the visible damage in the chromosomes. A fourth, the stamen-hair mutation assay (Trad-SHM), is a point mutation mitotic assay based on the expression of a recessive gene for flower color in heterozygous plants. The fifth assay is a cytogenetic test based on the formation of micronuclei (Trad-MCN) that result from chromosome breakage in the meiotic pollen mother cells.

This article examines the characteristics and fundamentals of the Trad-MCN and the Trad-SHM assays and reviews the results obtained to date with these systems in the assessment of environmental mutagenesis.     

具有原核基因启动子活性的蓖麻蚕染色体DNA片段

利用大肠杆菌启动子克隆载体pHE5,研究了蓖麻蚕染色体的Hind Ⅲ酶解片段在大肠杆菌中作为四环素抗性基因启动子的功能作用。蓖麻蚕染色体的Hind Ⅲ片段与pHE5重组,在大约10~6个重组子中获得953株启动子重组体。测定了这些含有重组质粒的菌株抗四环素能力,其中有4株在平板上抗四环素水平超过225微克/毫升。对其中pARP201的插入片段进行了限制性图谱分析和启动子活性区域的缺失定位,证明了pARP-DB(由pARP201衍生而来)中的约0.5kb的外源插入片段具有完整的原核启动子功能。我们分析了这段DNA的部分核苷酸顺序,发现它与原核基因启动子极其相似。     

Peculiarities of mitosis and nucleolar characteristics of the birch plantlets under antropogenous pollution

A study was made of some cytogenetic characteristics (mitotic activity, the level and spectrum of pathological mitosis, nucleolar features in root tip cells) in birch plantlets. The seeds were collected in four districts of Voronezh and in the ecologically clean territory. The index of mitotic activity has a considerable resistance to anthropogenous pollution. In the experimental areas, the level and spectrum of pathological mitosis increase. In contaminated areas we observed changes of nucleolar characteristics (the increased surface area of nucleoli and their higher number in cells, the increased number of cells with highly active types of nucleoli, the appearance of residual nucleoli). These changes can be considered as possible mechanisms of adaptation to stress due to antropogenous pollution. It is suggested that the use of such indices as single nucleolar surface area or the level of pathological mitosis may be perspective for cytogenetic monitoring of the environment, and for prognostification of environmental conditions suitable or unsuitable for the human health.     

Collective control without explicit coding: The case of communal nest excavation

The nests of social insects result from a succession of stimulus responses steps involving the environment, the workers, and the by-product of their activities (which modify their environment). In this way social insects can build without any reference to a blueprint. In this paper we explore the link between individual building behavior and the characteristics (form, size, location, etc.) of the structures produced. We show with a mathematical model (in the form of nonlinear differential equations) that social insects using behavioral mechanisms, which do not require an explicit measure of the nest and the colony size, can nevertheless effectively regulate, at the level of the colony, the size of the nest in response to changes in the size of the colony population. In addition, even though individual workers do not directly compare environmental characteristics, the colony can expand the nest preferentially in the most favorable zone. The models used show how such regulations and decision making can be a by-product of an amplifying communication between the builders and their work and how different patterns of building through time can be generated tuning the same basic rules.     

Factors affecting the proportion of sterile soldiers in growing aphid colonies

The proportion of sterile soldiers in an aphid colony is positively correlated with colony size. Assuming logistic growth of the aphid colony, Aoki and Kurosu (Insect Soc 50:256–261, 2003) presented an inequality that determines, for any colony size, whether a soldier or a reproductive will be added to the colony. To put it in words, if the marginal defensive efficacy of a soldier, multiplied by the number of reproductives, is larger than the mean productivity of reproductives without defense by that soldier, the soldier will be produced; if not, a reproductive will be produced. Based on Aoki and Kurosus inequality, we carried out simulations to determine whether the proportion of soldiers increased with colony size. Given a constant level of depredation per aphid and a constant number of predators, proportion of soldiers continued to increase with colony size unless a single soldier was very effective or unless carrying capacity was very large. Given a constant number of nongluttonous predators and a decreasing level of depredation per aphid, proportion of soldiers soon began to decrease after a peak. However, given an increasing number of nongluttonous predators to keep a constant level of depredation per aphid, proportion of soldiers again continued to increase. These results confirmed the argument that the proportion of soldiers can increase with colony size under a wide range of realistic assumptions.     

Reduced CENPU expression inhibits lung adenocarcinoma cell proliferation and migration through PI3K/AKT signaling

CENPU (centromere protein U), a centromere component essential for mitosis, relates with some cancers progression. However, it is not well illustrated in lung adenocarcinoma (LAC). Here, we aimed to investigate the potential effect of CENPU on LAC progression and prognosis. In this experiment, expression level of CENPU and association between its expression and LAC patients’ clinicopathological characteristics and prognosis were analyzed. The proliferation, migration and invasive abilities of LAC cells were determined by CCK-8, colony formation, transwell assays. Western blot was used to detect PI3K/AKT signaling key proteins. We found CENPU level was overexpressed in LAC tissues on comparing normal tissues. Moreover, CENPU overexpression correlated with clinicopathological variables and predicted an independent prognostic indicator in LAC patients. Functionally, CENPU downregulation significantly inhibited LAC cell proliferation, migration and invasion in, which was possibly mediated by PI3K/AKT pathway inactivation. Our findings insinuate targeting CENPU may be a potential therapeutic strategy for LAC.     

State of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L. generative sphere according to cytogenetic analysis in changing climate conditions on the territory of Voronezh oblast

A cytogenetic analysis of seed progeny of Pinus sylvestris L. trees growing in Voronezh oblast under different weather conditions (optimal and drought) has been conducted. It is found that in the years of drought the level of mitosis pathologies frequency increased, but it does not exceed norm. The spectrum of pathologies in these years is expanding, but it should be assumed that some of them can contribute to the reallocation of genetic material between chromosomes, which, in turn, will expand the range of norm reaction of an organism, thereby improving its ability to adapt to changing environmental conditions.     

石油泄漏对暴风海燕群体的短期影响

2002年11月原油泄漏前后,我们对伊比利亚半岛比斯开湾内的Aketx岛上的暴风海燕(Hydrobatespelagicus)进行了监测。1993 -2005年期间,利用雾网法调查了暴风海燕的数量,并通过直接观察法来统计雏鸟出飞率。在石油泄漏前,暴风海燕的种群数量亦存在年际波动,天气变化和食物丰盛度可能是引起这一现象的根本原因。在2003年,繁殖个体的身体条件较前些年差,繁殖对的数量和雏鸟成活率也有所下降。2004年繁殖对的数量明显少于2003年,繁殖个体的身体状况稍强于2003年,且所有卵都孵化成功。2005年的种群数量已经回升到石油泄漏前的水平,几乎所有配对的暴风海燕都能成功繁殖,亲鸟的身体条件也恢复到了石油泄漏前的水平。值得注意的是,这一群体中幼年个体的数量仍在减少,表明石油污染对种群数量的影响仍然存在,确定污染物在体内积累对这些海鸟所造成的影响将是下一步研究的重点。     

Study of the structure of colonies of active and inactive Actinomyces parvullus variants using luminescence and scanning microscopy]

The colony structure of the active and inactive proactinomycete-like variants of Actinomyces parvullus producing actinomycin D was studied with luminescent and scanning microscopy. Clear differentiation of the colony profile was shown by the structure and functions of the mycelium layers. A zone of active synthesis and accumulation of the antibiotic was observed in the colonies of the active variant in the upper part of the substrate mycelium with reddish-yellow self luminescence in UV light and characteristic close hyphae "cemented" by the intracellular substance. Formations of the granule type were often noted on the hyphae of that layer. The layer of the aerial mycelium was loosely connected with the substrate mycelium and consisted of sporophores and spore chains partially broken into single spores. The colonies of the inactive proactinomycete-like variant had a slightly differentiated profile with a sponge-like structure, no zones of the antibiotic synthesis being found. The presence of the intracellular substance was observed in the upper part of the colony supersubstrate mycelium.     

A perfect funeral with no corpse

"Indeed, the role in mitosis of the chromosome arms, which carry most of the genetic material, may be compared with that of a corpse at a funeral: they provide the reason for the proceedings but do not take an active part in them." (Mazia, 1961)     

Changes in cells's secretory organelles and extracellular matrix during endochondral ossification in the mandibular condyle of the growing rat

The mandibular condyle from 20-day-old rats was examined in the electron microscope with particular attention to intracellular secretory granules and extracellular matrix. Moreover, type II collagen was localized by an immunoperoxidase method. The condyle has been divided into five layers: (1) the most superficial, articular layer, (2) polymorphic cell layer, (3) flattened cell layer, (4) upper hypertrophic, and (5) lower hypertrophic cell layers. In the articular layer, the cells seldom divide, but in the polymorphic layer and upper part of the flattened cell layer, mitosis gives rise to new cells. In these layers, cells produce two types of secretory granules, usually in distinct stacks of the Golgi apparatus; type a, cylindrical granules, in which 300-nm-long threads are packed in bundles which appear "lucent" after formaldehyde fixation; and type b, spherical granules loaded with short, dotted filaments. The matrix is composed of thick banded "lucent" fibrils in a loose feltwork of short, dotted filaments. The cells arising from mitosis undergo endochondral differentiation, which begins in the lower part of the flattened cell layer and is completed in the upper hypertrophic cell layer; it is followed by gradual cell degeneration in the lower hypertrophic cell layer. The cells produce two main types of secretory granules: type b as above; and type c, ovoid granules containing 300-nm-long threads associated with short, dotted filaments. A possibly different secretory granule, type d, dense and cigar-shaped, is also produced. The matrix is composed of thin banded fibrils in a dense feltwork. In the matrix of the superficial layers, the "lucency" of the fibrils indicated that they were composed of collagen I, whereas the "lucency" of the cylindrical secretory granules suggested that they transported collagen I precursors to the matrix. Moreover, the use of ruthenium red indicated that the feltwork was composed of proteoglycan; the dotted filaments packed in spherical granules were similar to, and presumably the source of, the matrix feltwork. The superficial layers did not contain collagen II and were collectively referred to as perichondrium. In the deep layers, the ovoid secretory granules displayed collagen II antigenicity and were likely to transport precursors of this collagen to the matrix, where it appeared in the thin banded fibrils. That these granules also carried proteoglycan to the matrix was suggested by their content of short dotted filaments. Thus the deep layers contained collagen II and proteoglycan as in cartilage; they were collectively referred to as the hyaline cartilage region.     

Nest volatiles as modulators of nestmate recognition in the ant Camponotus fellah

When ants from alien colonies encounter each other the stereotypic reaction is usually one of aggressive behavior. It has been shown that factors such as queen-derived cues or nest-odors modulate this reaction. Here we examined whether nest volatiles affect nestmate recognition by observing the reaction of nestmates towards individual workers under one of four regimes: completely isolated; isolated but receiving a constant airflow from the mother colony; as previous but with the passage of nest volatiles towards the isolated ants blocked by adsorption on a SuperQ column; or reversed airflow direction-from the isolated ants to the nest interior. Ants that had been completely isolated for three weeks were subjected to aggressive behavior, but not those that had continued to receive airflow from the mother colony. Adsorbing the nest volatiles from the airflow by SuperQ abolished this difference, with these ants now also being subjected to aggression, indicating that nest volatiles can modulate nestmate recognition. Reverse airflow also reduced the level of aggression but to a lesser extent than airflow directed from the mother colony. In queenless colonies the overall aggression was reduced under all regimes, and there was no effect of flow, suggesting that the volatiles involved are queen-borne. The SuperQ adsorbed volatiles originated from Dufour's gland secretions of both workers and queen, implicating them in the process. Cuticular hydrocarbon profiles were not affected by exposure to nest volatiles, suggesting that the latter either constitute part of the recognition cues or affect worker behavior via a different, as yet elusive mechanism.     

Relationship of DNA repair to chromosome aberrations, sister-chromatid exchanges and survival during liquid-holding recovery in X-irradiated mammalian cells

The repair of X-ray induced DNA single strand breaks and DNA—protein cross-links was investigated in stationary phase, contact-inhibited mouse cells by the alkaline-elution technique. Approx. 90% of X-ray induced single strand breaks were rejoined during the first hour of repair, whereas most of the remaining breaks were rejoined more slowly during the next 5 h. At early repair times, the number of residual non-rejoined sungle strand breaks was approx. proportional to the X-ray dose. DNA—protein cross-links were removed at a slower rate (T1/2 approx. 10–12 h). Cells were held in stationary growth for various periods of time after irradiation before subculture at low density to score for colony survival (potentially lethal damage repair), chromosome aberrations in the first mitosis, and sister-chromatid exchanges in the second mitosis. Both cell killing and the frequency of chromosome aberrations decreased during the first several hours of recovery, reaching a minimum level by 6 h; this decrease correlated temporally with the repair of the slowly rejoining DNA-strand breaks. Relatively few sister-chromatid exchanges were observed when the cells were subcultured immediately after X-ray. The exchange frequency rose to maximum levels after a 4-h recovery interval, and returned to control levels after 12 h of recovery. The possible relationship of DNA repair to these changes in survival, chromosome aberrations, and sister-chromatid exchanges during liquid-holding recovery is discussed.     

Coupling mitosis to DNA replication: the emerging role of the histone H4-lysine 20 methyltransferase PR-Set7

To ensure accurate inheritance of genetic information through cell proliferation, chromosomes must be precisely copied only during S phase, and then correctly condensed and segregated during mitosis. Several new findings suggest that this tight coupling between DNA replication and mitosis is in part controlled by cell cycle regulated chromatin modifications, in particular due to the changing activity of lysine methyltransferase PR-Set7/SET8 that is responsible for the monomethylation of histone H4 at lysine 20. Cell cycle oscillation of PR-Set7 is orchestrated by ubiquitin-mediated proteolysis, and interference with this regulatory process leads to unscheduled licensing of replication origins and altered timing of mitotic chromosome compaction. This review provides an overview of how PR-Set7 regulates these two cell cycle events and highlights questions that remain to be addressed.     

Insulin-like growth factors, IGF-1, IGF-2 and somatomedin C trigger cell proliferation in mammalian epithelial cells cultured in a serum-free medium

A single insulin-like growth factor which constitutes part of a defined serum-free medium is sufficient to stimulate DNA synthesis and mitosis in mammalian lens epithelial cells. Rabbit lenses were cultured in KEI-4, a medium which mimics rabbit aqueous humor, or in KEI-4 containing insulin growth factor I (IGF I), insulin growth factor II (IGF II) or somatomedin C. The magnitude of DNA synthesis and mitosis was evaluated on whole mount preparations of the epithelium at various times of culture. IGF I and II, the most highly purified of the insulin-like growth factors, and somatomedin C were equipotent lens mitogens, were active at the ng level, were more mitogenic toward lens epithelial cells than insulin, and initiated cell proliferation throughout the normally amitotic central region of the lens epithelium. The time course of the mitotic response elicited by the insulin-like growth factors was identical to that noted in lenses cultured in medium supplemented with serum or insulin. The present results, coupled with those of other investigators, suggest that insulin-like factors may regulate cell division in the mammalian lens in vivo.