Ordination analysis and bioindices based on zoobenthos communities used to assess pollution of a lake in southern Finland

The suitability of an ordination method, detrended correspondence analysis (DCA), was tested in assessing the degree of pollution of a large lake on the basis of the zoobenthos communities. Lake Etelä-Saimaa, in southern Finland, was originally oligotrophic but is now heavily loaded by effluents from the wood-processing industry. Comparison between areas was complicated by variation in the water depths of the lake sub-basins. A horizontal pollution gradient could, however, easily be detected by means of the DCA in both the profundal and sublittoral zones. The benthic quality index (BQI) based on the composition of the profundal chironomid fauna failed at some stations because the indicator species were lacking, despite enlargement of the indicator species pool. The BQI based on the oligochaetes could be calculated at almost all the stations. This index was modified by altering the empirical constants for two species. Diversity indices and the occurrences of single species had a limited value in the water quality assessment. The study concluded that DCA ordination is a powerful tool in evaluation of pollution. The method gives the best results when the sampling network is carefully planned and the material represents all sections of the underlying environmental gradients, e. g. a gradient from oligotrophy to eutrophy or heavy pollution.     

Detection and partial characterization of two antigenically distinct β-amylases in developing kernels of wheat

A -amylase (EC 3.2.1.2) was identified in the outer pericarp (P) of developing seeds of wheat (Triticum aestivum L.) and compared with the well known -amylase which is synthesized during seed development in the starchy endosperm (E). The enzyme P already exists in the tissues before anthesis and vanishes at the time when E starts to accumulate. The isoelectric-focusing patterns of P and E are very similar. The relative molecular weight (M_r) of P is slightly higher than that of E (66 and 64.5 kDa, respectively). Both P and E exhibit common epitopes in addition to epitopes specific for each of them. The two enzymes were identified in small amounts in the green tissues of the developing seeds (inner pericarp and testa). No antigenic difference was detected between P and the -amylases of roots and leaves.Abbreviations P pericarp -amylase - E endosperm -amylase - IS1 anti--amylase immune serum - IS2 anti- and anti- amylase immune serum - IS3 anti- amylase immune serum - IEF isoelectric focusing - IgG immunoglobulin G The authors thank Dr. P. Ziegler (Universität Bayreuth, FRG) for stimulating discussion and for useful suggestions during the writing of the text. The authors thank Miss C. Mayer for her skillful technical assistance.     

Alkyl-ether phosphoglycerides influence calcium fluxes into human endothelial cells

Suspended or adherent human endothelial cells (HEC) treated with 5 to 100 nM 1-O-octadecyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC, platelet-activating factor) showed a marked concentration and temperature-dependent increase in calcium uptake. This effect was also elicited by some AGEPC analogs. At 10 nM, the relative potencies were AGEPC = 100; 1-O-octadecyl-2-acetyl-sn-glycero-3-phosphoric acid (AGEPA) = 52.9; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphoethanolamine (AGEPE) = 20; 1-O-octadecyl-2-deoxy-2-acetamido-sn-glycero-3-phosphocholine (2-acetamido-analog)-inactive at 100 nM = 25; 1-octadecyl-2-methoxy-sn-glycero-3-phosphocholine(2-methoxy analog)-inactive, and at 100 nM = 50. 1-O-octadecyl-2-lyso-sn-glycero-3-phosphocholine(lyso-GEPC) (100 nM) was inactive. The increase in calcium uptake was accompanied by a rise in membrane-associated calcium. The ratio between nonmembrane-bound intracellular calcium and membrane-associated calcium was constant for all agonists. CV-3988, a specific AGEPC antagonist, inhibited the effect of AGEPC. Preexposure of adherent HEC to AGEPC inhibited calcium uptake upon subsequent stimulation, suggesting a deactivation of the putative receptor. AGEPC (5 to 100 nM), but not lyso-GEPC, also stimulated calcium-efflux from calcium-preloaded, adherent HEC. AGEPC and 2-acetamido-analog, at concentrations able to induce calcium influx, did not elicit the production of 6-keto-PGF1 alpha.     

Global database of plants with root‐symbiotic nitrogen fixation: NodDB

Plants associated with symbiotic N‐fixing bacteria play important roles in early successional, riparian and semi‐dry ecosystems. These so‐called N‐fixing plants are widely used for reclamation of disturbed vegetation and improvement of soil fertility in agroforestry. Yet, available information about plants that are capable of establishing nodulation is fragmented and somewhat outdated. This article introduces the NodDB database of N‐fixing plants based on morphological and phylogenetic evidence (available at https://doi.org/10.15156/bio/587469 ) and discusses plant groups with conflicting reports and interpretation, such as certain legume clades and the Zygophyllaceae family. During angiosperm evolution, N‐fixing plants became common in the fabid rather than in the ‘nitrogen‐fixing’ clade. The global GBIF plant species distribution data indicated that N‐fixing plants tend to be relatively more diverse in savanna and semi‐desert biomes. The compiled and re‐interpreted information about N‐fixing plants enables accurate analyses of biogeography and community ecology of biological N fixation.     

Fatty acids,starch and biomass of Scots pine needles and roots in open-air ozone exposure

Scots pine (Pinus sylvestris L.) seedlings were fumigated with 1.2–1.5 x ambient ozone (cumulative exposure) over 2 seasons in an open-air experiment. Starch and fatty acid concentrations were analyzed in needle and root tissue in the summer, autumn and early winter. Seedling growth was determined by measuring the height of the stem and the total shoot and root biomass. Significant decreases in growth were found in exposed seedlings, even though visible symptoms were lacking. Almost significant reductions in needle and root starch concentrations were found. In the ozone treated foliage, significant increases in myristic acid (140) were detected, but the major fatty acids remained unchanged. Fatty acid ratios showed that the degree of unsaturation decreased in treated needles in the summer. In the roots of ozone treated seedlings, changes in fatty acids were different from those in the foliage. Decreases of the main root fatty acids (160, 180, 181, 18:2, 183) were detected in the summer. These results show that Scots pine is susceptible to enhanced levels of ozone. If the tropospheric ozone levels continue to increase it may have deleterious effects on Scots pine forests in Finland.     

Differentiation of adult Leydig cells

Adult Leydig cells originate within the testis postnatally. Their formation is a continuous process involving gradual transformation of progenitors into the mature cell type. Despite the gradual nature of these changes, studies of proliferation, differentiation and steroidogenic function in the rat Leydig cell led to the recognition of three distinct developmental stages in the adult Leydig cell lineage: Leydig cell progenitors, immature Leydig cells and adult Leydig cells. In the first stage, Leydig cell progenitors arise from active proliferation of mesenchymal-like stem cells in the testicular interstitium during the third week of postnatal life and are recognizable by the presence of Leydig cell markers such as histochemical staining for 3β-hydroxysteroid dehydrogenase (3β-HSD) and the present of luteinizing hormone (LH) receptors. They proliferate actively and by day 28 postpartum differentiate into immature Leydig cells. In the second stage, immature Leydig cells are morphologically recognizable as Leydig cells. They have an abundant smooth endoplasmic reticulum and are steroidogenically active, but primarily produce 5-reduced androgens rather than testosterone. Immature Leydig cells divide only once, giving rise to the total adult Leydig cell population. In the third and final stage, adult Leydig cells are fully differentiated, primarily produce testosterone and rarely divide. LH and androgen act together to stimulate differentiation of Leydig cell progenitors into immature Leydig cells. Preliminary data indicate that insulin like growth factor-1 (IGF-1) acts subsequently in the transformation of immature Leydig cells into adult Leydig cells.     

Optimization of reproductive effort and foraging time in mammals: The influence of resource level and predation risk

Summary The trade-off between fitness benefits from foraging and associated costs in terms of predation risk is analysed by a simple model which takes into account the differential predation risk for reproducing and non-reproducing individuals. The currency that animals are assumed to maximize is their expected absolute fitness (probability of survival plus half of the expected litter size) after a potential reproductive period. Depending on resource levels and predation risk, this maximization can be achieved by (1) opting for individual survival and behaving as a strict time minimizer, (2) by reproducing at the maximal rate and behaving as a strict energy maximizer or (3) by submaximal reproductive effort and a behaviour intermediate between time minimization and energy maximization. Small changes in the availability of food or cover or in the density of predators can shift the optimum from one strategy to another. The shift is particularly abrupt, if predation pressure increases and the availability of resources remains high. This could explain the spatial and temporal variation in the reproductive effort and body weight observed in boreal small mammals with sustained, multiannual population fluctuations.     

Linkage of the long QT syndrome to the short arm of chromosome 11: use of five highly polymorphic markers towards more detailed localization of the mutant gene

The long QT syndrome is an autosomally dominantly inherited cardiac disorder characterized by abnormalities of myocardial repolarization, exercise- or stress-related syncopal attacks and risk of sudden death due to cardiac arrhythmias. Genetic linkage studies have defined three LQT loci on chromosomes 11p15.5, 3q21–24 and 7p35–36. We performed linkage analyses in three Finnish LQT families using five amplifiable markers assigned to chromosome 11p15. By multipoint linkage analyses we obtained a maximal lod score of 5.503, suggesting that the LQT1 locus maps between D11S922 and D11S1338 on chromosome 11. Our data provide a step towards closer definition of the exact borderlines of the LQT1 locus in chromosome 11 and demonstrate markers with high utility in identification of gene carriers in the affected families.     

Female Black GrouseTetrao tetrix shift nest site after nest loss

Female Black Grouse that lost their nest to predation had a longer breeding dispersal distance between consecutive nests within and between seasons than successful females between seasons. This response might be a tactic to avoid egg predation, because predators may revisit those sites where they have been previously successful. Switching of nesting habitat was not associated with nest fate, suggesting that nest predation risk was not related to habitat type. However, the benefits of switching nest site remained somewhat obscure.

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Zusammenfassung Birkhennen, die ihre Nester durch Nestraub verloren, legten ihre Nester in weiteren Entfernungen zwischen sukzessiven Brutversuchen sowohl innerhalb eines Jahres als auch in Folgejahren an, als erfolgreiche Hennen zwischen den Jahren. Dieses Verhalten kann eine Anpassung sein, Nestraub zu vermeiden, weil Nesträuber möglicherweise dieselben Plätze wieder besuchen, an denen sie Nester gefunden haben. Ein Wechsel des Nisthabitats hatte jedoch nicht mit dem Bruterfolg korreliert, so daß wahrscheinlich kein Zusammenhang zwischen Nestraub und Typus des Nisthabitats besteht. Es konnte nicht eindeutig geklärt werden, ob der Wechsel des Nistplatzes für die Hennen erfolgreich war.