Biomanipulation by ecotone management in a lowland reservoir

The comparative studies on fry of dominant fish species in the lowland Sulejow Reservoir have demonstrated the importance of an unstable ecotonal shoreline zone in whole system dynamics, which affects water quality. Ecotone zone utilization by fish determines their reproductive success and consequently pressure of fry on a zooplankton community. Density of perch, which dominates in the fry community of the Reservoir, influences the utilization of ecotonal resources by dominant cyprinid fry-roach. A reverse relationship between perch and roach fry densities has been demonstrated, which in turn, affects utilization of zooplankton by roach fry. At stations of highest perch density roach reduces feeding on zooplankton and eats more algae and insects. The knowledge of competitive relations between perch and cyprinid fry has been an important aspect of application of the biomanipulation concept in the reservoir ecosystem, to improve fish yield and water quality. Hypothetical models of energy flow through the reservoir's ecosystem with poor and well developed flooded riparian ecotonal zones are established.     

Replication variants of the human inactive X chromosome

Replication variants of the inactive X chromosome were investigated in lymphocytes from six donors by means of terminal BrdU or thymidine incorporation. There were interindividual differences in the incidence of particular variants. In endoreduplicated and tetraploid cells both allocyclic X chromosomes showed the same replication sequence. The Xp22 band of the allocyclic X chromosome seemed to replicate later than the homologous material in some cells. Initiation time of DNA synthesis within the inactive X chromosome was found to be stable; termination time, however, varied greatly relative to the other chromosomes. Early completion of replication within the heterochromatic X chromosome could be demonstrated preferentially for the Xq25–27 terminal sequence, but other variants expressed the phenomenon also. A variable replication rate of the inactive X chromosome is believed to be responsible for its asynchronous, independent replication. The biological significance of the phenomenon is discussed with respect to cell differentiation.     

The long-term fate of neurons in allografts of ganglia in AG-B-compatible normal and immunologically tolerant rats

Neurons in Ag-B-incompatible allografts of ganglia are acutely rejected while those in Ag-B-compatible grafts are able to survive the immune reaction directed against them. The present study was undertaken to determine the long-term fate of neurons in allografts of ganglia in Ag-B-compatible rats. Isogenic strains of Ag-B-compatible adult Lewis (LE) and Fischer (FR) rats were used. The sensory nodose ganglia were reciprocally exchanged between normal LE and FR and between LE and FR animals rendered immunologically tolerant of each other's histocompatibity antigens. The findings were similar in both rat strains and revealed that although neurons and glial cells (i.e., satellite and Schwann cells) could survive for prolonged periods they were nevertheless eventually rejected by normal (nonimmunosuppressed) recipients. On the other hand, neurons and glial cells survived indefinitely in allografts in tolerant rats. Moreover, these neurons were functional because they regenerated nerve fibers into cotransplanted isografts of tongue and exerted the neurotrophic influence of inducing taste bud regeneration. The results demonstrate that, unlike kidney and heart, neurons in ganglia allografts cannot survive indefinitely without immunosuppression in Ag-B-compatible animals. Nevertheless, the permanent survival and function of neurons in Ag-B-compatible grafts can be achieved, as it is in Ag-B-incompatible ganglia grafts, by rendering the recipient immunologically tolerant.     

Ca2+/Mg(2+)-dependent nuclease: tissue distribution, relationship to inter-nucleosomal DNA fragmentation and inhibition by Zn2+.

Ca2+/Mg(2+)-dependent endonuclease has been implicated in the extensive internucleosomal DNA fragmentation that accompanies apoptosis (gene-directed cell death). We present further evidence that this enzyme is involved in apoptosis. Ca2+/Mg2+ nuclease activity was increased about 6-fold during colchicine-induced apoptosis in human chronic lymphocytic leukaemia cells. The increase in activity coincided with onset of DNA fragmentation. Spleen, liver, kidney and thymus expressed high levels of this enzyme while lung, brain, heart and testis contained little activity. Cells from tissues with high Ca2+/Mg2+ nuclease activity underwent rapid DNA fragmentation in response to a Ca2+ flux. Physiological concentrations of Zn2+ known to inhibit both apoptosis and DNA fragmentation also inhibited Ca2+/Mg2+ nuclease activity.     

Applications of immortalized cells in basic and clinical neurology

Immortalized cell lines can serve as model systems for studies of neuronal development and restoration of function in models of neurological disease. Cell lines which result from spontaneous or experimentally-induced tumors have been used for these purposes. More recently, the techniques of genetic engineering have resulted in the production of cell lines with specific desired characteristics. This has been accomplished by insertion of a desired gene into a pre-existing immortal cell or by immortalizing primary cells. The production of immortal cell lines using temperature-sensitive immortalizing genes offers an additional method of controlling gene expression, and thereby controlling cell proliferation and differentiation. In the nervous system, these techniques have produced immortal cell lines with neuronal and glial properties.     

Correlates of pentraxin 3 serum concentration in men and women with type 2 diabetes

Elevated levels of plasma pentraxin 3 (PTX3), a marker of inflammation, are associated with the risk of developing cardiovascular diseases in the general population, as well as in patients with type 2 diabetes (DM2). In this study, we aimed to determine factors associated with PTX3 serum concentrations in men and women with DM2. The study included 116 consecutive patients (67 men and 49 women) with DM2 from an outpatient diabetic clinic. Men were characterised by lower age and higher uric acid, creatinine and bilirubin concentrations and waist/hip ratio than women. In women, low-density lipoprotein cholesterol (LDL-C) levels were higher than in men. In men, median (interquartile range) values of PTX3 concentration were 4.02 (1.99), and in women they were 4.53 (3.31) ng/ml (NS). In men, PTX3 concentrations correlated with total cholesterol (TC), triglycerides, apolipoprotein (Apo) C3, Apo B48, Glc and creatinine levels. In women, PTX3 correlated significantly with TC and LDL-C and Apo B100. Partial regression analysis revealed that after adjusting for age, PTX3 concentrations in men were significantly associated with TC, LDL-C, triglycerides, creatinine, Apo C3 and Apo B48, while in women they were associated with TC, LDL-C and Apo B100. The results could be of importance in sex-specific prevention of vascular complications in DM2 patients.     

Molecular Architecture of Plant Thylakoids under Physiological and Light Stress Conditions: A Study of Lipid–Light-Harvesting Complex II Model Membranes

In this study, we analyzed multibilayer lipid-protein membranes composed of the photosynthetic light-harvesting complex II (LHCII; isolated from spinach [Spinacia oleracea]) and the plant lipids monogalcatosyldiacylglycerol and digalactosyldiacylglycerol. Two types of pigment-protein complexes were analyzed: those isolated from dark-adapted leaves (LHCII) and those from leaves preilluminated with high-intensity light (LHCII-HL). The LHCII-HL complexes were found to be partially phosphorylated and contained zeaxanthin. The results of the x-ray diffraction, infrared imaging microscopy, confocal laser scanning microscopy, and transmission electron microscopy revealed that lipid-LHCII membranes assemble into planar multibilayers, in contrast with the lipid-LHCII-HL membranes, which form less ordered structures. In both systems, the protein formed supramolecular structures. In the case of LHCII-HL, these structures spanned the multibilayer membranes and were perpendicular to the membrane plane, whereas in LHCII, the structures were lamellar and within the plane of the membranes. Lamellar aggregates of LHCII-HL have been shown, by fluorescence lifetime imaging microscopy, to be particularly active in excitation energy quenching. Both types of structures were stabilized by intermolecular hydrogen bonds. We conclude that the formation of trans-layer, rivet-like structures of LHCII is an important determinant underlying the spontaneous formation and stabilization of the thylakoid grana structures, since the lamellar aggregates are well suited to dissipate excess energy upon overexcitation.     

A Supposed Eupelycosaur Body Impression from the Early Permian of the Intra-Sudetic Basin,Poland

We describe a new specimen of a supposed Paleozoic tetrapod body impression from the Lower Permian S?upiec Formation in the Intra-Sudetic Basin, Poland. The size, integument morphology of belly and part of tail imprints, and the morphology of a well-preserved pes track diagnose the specimen and readily distinguish it from other described specimens of body impressions of Paleozoic tetrapods. The eupelycosaur identity of this new specimen is based on the identification of the footprint Dimetropus leisnerianus (Geinitz, 1863 Geinitz, H. B. 1863. Beiträge zur Kenntnis der organischen Überreste in der Dyas (oder permischen Formation zum Theil) und über den Namen Dyas. Neues Jahrbuch für Mineralogie, Geologie und Paläontologie, : 385–398.  [Google Scholar]), which is connected with the inferred body imprint. The morphology of integument impressions indicates the presence of the various-sized square or rectangular-shaped scales on the bottom part of the belly and tail of this eupelycosaurid trackmaker.