The environmental regulation of adult diapause in Drosophila littoralis

Drosophila littoralis overwinters in the adult stage in a reproductive diapause. During the warm season there are one or two generations in Finland. The diapause appears to be a prolongation of the post-eclosion immaturity of young females. The termination of diapause is controlled by a combination of adequate temperature and sufficiently long photophases. The diapausing status of females is ascertained by inspecting the developmental stage of their ovaries. In laboratory experiments the maturity of ovaries is not closely correlated with the receptivity of females.     

Lymphoid cell subclasses in rejecting renal allograft in the rat

We have quantitated the frequency of lymphoid cell subsets in rejecting renal allografts and in the spleen of the allograft recipient during drug-unmodified rejection in the rat. The number of inflammatory (white) cells in the graft was approximately similar to the number of white cells responding to the allograft in the recipient spleen. The inflammatory population of the graft consisted of lymphoid cells and mononuclear phagocytes, with increasing numbers of macrophages toward the end of rejection. Analysis of allograft cellular dispersates with monoclonal antibodies directed to the lymphoid cell subsets demonstrated that although the majority of allograft-infiltrating lymphocytes were T cells, a sizable B-cell proliferation and immunoglobulin synthesis was associated with the inflammatory response of rejection. Within the T-cell subset, the T suppressor/killer cells predominated in the graft whereas the predominant lymphoid cell subset responding to the allograft in the recipient spleen was the T helper cell.     

Flow cytometric detection of ornithine decarboxylase activity in epidermal cell subpopulations

Using flow cytometry in combination with membrane permeabilization techniques to enhance binding of antibodies with immunoreactive protein within the cytoplasm, we have developed a method to examine the ornithine decarboxylase (ODC) activity present within subpopulations of epidermal cells following acute and chronic exposure to the phorbol ester tumor promoter 12-0-tetradecanoylphorbol-13-acetate (TPA). The method described has the sensitivity to detect basal levels of ODC as well as increases in ODC at early time points following treatment with TPA and has the additional advantage of allowing subpopulation identification and characterization.     

Spatial and environmental components of variation in the distribution patterns of subarctic plant species at Kevo, N Finland — a case study at the meso-scale level

This study presents a quantitative partitioning of the total variance in the patterns of occurrence of 231 vascular plant taxa in 362 1 × 1 km grids in the Kevo Nature Reserve into four independent components: purely spatial variation, spatially structured environmental variation, non-spatial environmental variation, and unexplained variation. This partitioning is done with (partial) constrained ordinations (canonical correspondence analysis) and associated Monte Carlo permutation tests. The numerical results suggest that most of the biological variance captured by the external explanatory variables is related to 'local' meso-scale environmental factors, as 12.6% of the variation in the species data is explained solely by the environmental variables. Part of the variance (6%) represents a spatially covarying environmental component, but only a very small part, ca 2%, is related to purely spatial variation. The amount of unexplained variation is very high (>75%). The results are compared and discussed in relation to the relative amounts of these four variance components at broader- and finer-scales and to the concepts of domains and transition zones of scales in biological patterning.     

Identifying resuspended particles using isotope ratios

Three simple methods were developed to estimate the proportion of particles in lake water derived from resuspended material. These techniques use the different distributions of long and short-lived radioisotopes sorbed onto particles and were tested in the three basins of Lake Erie using ⁷Be, ¹³⁷Cs and ²¹⁰Po/²¹⁰Pb.While the concentration of ²¹⁰Po on particles did not vary significantly in the lake, resuspended particles were characterized by high concentrations of ¹³⁷Cs and low concentrations of ⁷Be. The distribution of these radioisotopes is consistent with a simple mixing model in which the fraction of particles in the lake water derived from resuspension ranged from 8% to about 100%. Higher concentrations of resuspended particles were found in deeper samples from the nepheloid layer and in the shallow western basin where thermal stratification was very weak.     

Response by macrozoobenthos biomass to water level regulation in some Finnish lake littoral zones

The relationship of the macrozoobenthos biomass in the littoral area to the yearly fluctuation in water level and the characteristics of the area or lake are studied using data collected from sheltered bays in regulated and natural waters. Most of the lakes were clear and oligotrophic. The benthos biomass at all depths in the littoral decreased with increased water level fluctuation, provided that the transparency of the water was uniform.The macrozoobenthos biomass in the 0–3 m depth zone could be predicted fromlog macrozoobenthos biomass (mg ODW) m^-2=4.25-1.33 (log Biomass Index) in which the Biomass Index is calculated as% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeOqaiaabM% gacaqGVbGaaeyBaiaabggacaqGZbGaae4CaiaabccacaqGjbGaaeOB% aiaabsgacaqGLbGaaeiEaiaab2dacaqGGaGaaeiiaiaabccacaqGGa% GaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabcca% caqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiai% aabccadaWcaaabaeqabaGaae4DaiaabggacaqG0bGaaeyzaiaabkha% caqGGaGaaeiBaiaabwgacaqG2bGaaeyzaiaabYgacaqGGaGaaeOzai% aabYgacaqG1bGaae4yaiaabshacaqG1bGaaeyyaiaabshacaqGPbGa% ae4Baiaab6gacaqGGaGaaeyAaiaab6gacaqGGaGaaeiDaiaabIgaca% qGLbGaaeiiaiaabchacaqGYbGaaeyzaiaabAhacaqGPbGaae4Baiaa% bwhacaqGZbGaaeiiaiaabMhacaqGLbGaaeyyaiaabkhaaeaacaqGOa% GaaeyBaiaabUdacaqGGaGaae4yaiaabggacaqGSbGaae4yaiaabwha% caqGSbGaaeyyaiaabshacaqGLbGaaeizaiaabccacaqGMbGaaeOCai% aab+gacaqGTbGaaeiiaiaab2gacaqGVbGaaeOBaiaabshacaqGObGa% aeiBaiaabMhacaqGGaGaaeyBaiaabwgacaqGHbGaaeOBaiaabccaca% qG2bGaaeyyaiaabYgacaqG1bGaaeyzaiaabohacaqGPaaaaeaacaqG% tbGaaeyzaiaabogacaqGJbGaaeiAaiaabMgacaqGGaGaaeizaiaabM% gacaqGZbGaae4AaiaabccacaqG2bGaaeyyaiaabYgacaqG1bGaaeyz% aiaabccacaqGPbGaaeOBaiaabccacaqG0bGaaeiAaiaabwgacaqGGa% Gaae4CaiaabggacaqGTbGaaeyzaiaabccacaqGVbGaaeiCaiaabwga% caqGUbGaaeiiaiaabEhacaqGHbGaaeiDaiaabwgacaqGYbGaaeiiai% aabohacaqGLbGaaeyyaiaabohacaqGVbGaaeOBaiaabccacaqGOaGa% aeyBaiaabMcaaaaccaGae8hiaaIaaKiEaiab-bcaGiaaigdacaaIWa% GaaGimaiaac6caaaa!CBD8!\[{\text{Biomass Index = }}\frac{\begin{gathered} {\text{water level fluctuation in the previous year}} \hfill \\ {\text{(m; calculated from monthly mean values)}} \hfill \\ \end{gathered} }{{{\text{Secchi disk value in the same open water season (m)}}}} \user1{x} 100.\]The whole illuminated littoral shifts due to water level fluctuation, which disturbs the zonation of the benthos. Such an increase or decrease in benthic biomass has been observed after one year of disturbance due to water level fluctuation. It need, however, a study based on the carefully planned and collected data, in which it can be taken account by a multivariate statistical analysis also the interactions between the important factors affected the littoral benthos.     

1H Nuclear Magnetic Resonance Spectroscopy Study of Cerebral Glutamate in an Ex Vivo Brain Preparation of Guinea Pig

Abstract: Cerebral glutamate was monitored in a superfused cerebral cortical preparation by ¹H NMR spectroscopy using a semiselective spin-echo sequence N -acetyl aspartate (NAA) as an internal concentration reference. During controlled metabolic conditions, the cerebral ¹H NMR-detected glutamate-to-NAA ratio was ∼ 20–30% lower than expected from the ratio of neutralized perchloric acid extracts of the preparations. Inhibition of respiration in the presence of glucose did not change the ¹H NMR glutamate-to-NAA ratio in brain slice preparation. In contrast, either complete depletion of ATP during cyanide poisoning together with 0 m M glucose, anoxia in the absence of glucose, or treatment with nigericin or with a protonophore, carbonyl cyanide- m -fluorophenylhydrazone, increased ¹H NMR-detected glutamate/NAA in the cerebral preparations without a change in the relative and absolute concentration ratios determined from the tissue acid extracts. Spin-spin relaxation times of glutamate and NAA peaks in anoxic slices were 749 ± 89 and 729 ± 94 ms, respectively, and thus, the portion of glutamate that could not be detected by ¹H NMR was quantified in absolute terms. It was calculated that an increase in the glutamate-to-NAA ratio from 0.55 ± 0.02 to 0.67 ± 0.02 during aglycemic anoxia corresponded to some 6 mmol/kg of tissue dry weight of glutamate from the total concentration of 28 mmol/kg dry weight. It is suggested that this 22% of total glutamate pool is present in a noncytoplasmic compartment during controlled metabolic state.     

Variation in life history responses of Daphnia to toxic Microcystis aeruginosa

Three clones of Daphnia pulex and two clones of Daphnia longispinawere exposed to toxic Microcystis aeruginosa for 21 days ina lifetable experiment. The growth and reproduction of individualdaphnids were followed daily to study the long-term effectsof toxic Microcystis. Exposure to Microcystis increased mortality,decreased growth, delayed maturation and decreased offspringproduction, indicating nutritional deficiency and toxic effects.We found variation in life history responses between speciesand among clones. Our results suggest that toxic cyanobacteriamay act as a modifying agent in zooplankton communities at boththe species and clonal level.     

Development of needle retention in Scots pine (Pinus sylvestris) in 1957–1991 in northern and southern Finland

The needle trace method was used to study retrospectively the long-term latitudinal variation in needle retention in Scots pine (Pinus sylvestris L.) in Finland. The mean annual summer needle retention (ANR) along the main stem varied from 3.4 to 6.0 needle sets during the period 1957–1991. The lowest values were observed in southern and the highest in northern Finland. The length of the growing season, expressed as the thermal sum (threshold value +5 °C), was negatively correlated with the mean ANR (r=-0.96). The geographical needle retention pattern (NRP) for the period 1957–1991 showed a clearly increasing trend from 1957 to 1969 (southern Finland) and to 1975 (northern Finland); thereafter, the NRP tended to decrease close to its minimum value recorded in 1991. The general level of the NRP was approximately 5.0 needle sets in northern Finland and 3.5–4.0 needle sets in southern Finland. The NRP, with its 6–12 year cycle for southern Finland, was clearly periodical. Differences in the NRP among the ten stands in southern Finland were small, whereas the said periodicity was missing and the differences were high among the stands in northern Finland. The results indicate that variation in the number of needle sets, viz. defoliation of pines, is a normal phenomenon. The role of net carbon assimilation as a regulator of the number of needle sets is discussed.     

Fermentation of Bacillus thuringiensis for exotoxin production: Process analysis study

The exotoxin produced by certain serotypes of Bacillus thuringiensis was used as a means of microbiological control of the larval development of flies. The optimal batch cultivation conditions with respect to pH, temperature, aeration, agitation, and initial concentration of growth-limiting substrate were determined. A dynamic model describing the process was designed and fitted to the experimental data. The application of a method for estimating exotoxin and bacterial concentrations from on-line measurable quantities such as oxygen consumption and heat production is presented.