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Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation. ispartof: ECOLOGY LETTERS vol:25 issue:2 pages:255-263 ispartof: location:England status: published

Sampling efficiency is directly linked to (faunistic) stability issues of any sampled site. It is more probable to sample a high proportion of the species occurring at a certain site, if communities remain constant in species composition with time. For this study 64 groundwater monitoring wells in Southwestern Germany were sampled six times to determine sampling efficiency. False-Negative (FN) rates and SIMPER values, two independent models expressing Faunistic values of the sampled bores, were calculated and three groups of faunistic stability could be identified based on calculated SIMPER-values. FN-rates as well as SIMPER values proved to be a valuable approach for the estimation of faunistic stability/instability, as these methods showed a highly negative correlation with each other. To collect 95% of species a number of 1.7–16.4 samples was calculated to be necessary depending on faunistic stability of the sampled habitat. On the six sampling occasions the sites harbouring a stable groundwater meiofauna resulted in 98.2% of occurring species, whereas the percentage decreased over intermediate sites (94.9%) and stressed sites (79.5%). A consequence of the data presented may be to view surveys using only two samples as campaign with orienting character, with further studies of stability issues of groundwater communities which would provide efficient and effective sampling for various kinds of sites.

In the sediments of a southwestern German headwater, pumping and two types of unbaited traps were compared with respect to their suitability for the sampling of interstitial meiofauna. The aim of the study was to discover whether the type-2 trap, having been developed for universal use, could be utilised in the hyporheic zone, as well as in groundwater. Trap samples demonstrate both greater abundance and taxonomic richness than those samples obtained by pumping, though very few differences could be detected between the two types of trap. The taxonomic composition, however, was found to be very similar for all three sampling methods. Other researchers also observed a high similarity of stygofaunal communities between pumped groundwater and the water of the bores, which act as traps. This would imply that not only do trap samples as well or better reflect community structure of the surrounding sediment than does pumping, but also that the type-2 trap is, indeed, suitable for the sampling of meiofauna in both the hyporheic zone and in groundwater.

The presence of C-peptide, proinsulin, insulin-A-chain, and glicentin in human fetal pancreatic cells by using the PAP-technique was investigated and the results obtained compared with the occurrence of insulin or glucagon immunoreactive cells. In pancreatic sections obtained from 10 weeks old human fetuses we could identify cells reacting with antibodies directed against C-peptide, proinsulin, and insulin-A-chain. The majority of the cells were found in the duct epithelium and their number increased from the 10th to 14th week forming clusters near the ducts. The number and localization of the cells correspond exactly to the insulin positive cells. The presence of proinsulin and insulin-A-chains is a further proof of biological activity already in an early step of fetal development. The presence of glicentin-positive cells in the 10th week of gestational age as well as cells reacting with glucagon antibodies provide evidence for active glucagon biosynthesis. The number of these cells increased markedly in the 14th week of gestational age.

Remarkably high concentrations of α-hexachlorocyclohexane (α-HCH), cis -heptachlorepoxide and oxychlordane were found in roe-deer liver samples both from the northern and southern German states Schleswig-Holstein and Baden-Wurttemberg, respectively. The data revealed no significant regional differences, but they showed some common characteristics: a preferential degradation of (+)-α-HCH, and a preferential enrichment of (+)-oxychlordane and of (+)- cis -heptachlorepoxide as determined by chiral capillary gas chromatography using modified cyclodextrin phases. Calculation of the spearman rank correlation coefficients r s supported the assumption that higher concentrations of α-HCH may result in a stronger decomposition of the (+)-enantiomer, while higher levels of cis -heptachlorepoxide and oxychlordane appear to lead to a faster decomposition of the respective (-)-enantiomer or a preferential formation of the respective (+)-enantiomer.

Summary After burial in a sediment, organic matter is altered by various diagenetic processes to insoluble, highly polymeric kerogen and a lipid fraction, composed mainly of hydrocarbons. The as yet uninvestigated potential of factor 430, a porphinoid compound, to act as a marker for methanogenic archaebacteria is mentioned in relation to the petroporphyrins found in petroleums and sediments. The evidence for isoprenoid ethers and alkanes found in the geological record back to 3 billion years is summarized. An attempt is made to relate the findings to potential archaebacteria precursors. The C 18 –C 26 isoprenoid alkanes found in several facies of the oldest known sediments in the Isua district of W. Greenland are discussed with respect to the apparent metamorphic alterations of the host rocks. The evidence indicates that archaebacteria have existed for at least one billion years, possibly even for more than three billion years.

The regional and cellular distribution of insulin-like immunoreactivity throughout the CNS of three rodent species were investigated using an immunofluorescence technique. No principal differences in the content and distribution of insulin-like material were revealed between lean animals and mice suffering from a genetically determined diabetes mellitus.

Summary Using an indirect fluorescence technique and the unlabelled enzyme technique of Sternberger (PAP-techniques) we were able to demonstrate a widespread distribution of insulin, C-peptide and glucagon throughout the human brain.

Investigation of glucagon secretion in isolated Wistar rat islets was carried out to elucidate further the regulatory function of glucose and arginine on pancreatic A-cells. The suppressive effect of D -glucose could also be demonstrated with L -glucose, D -mannose, D -fructose, D -galactose, D -glyceraldehyde and DL -dihyroxyacetone, but not in the presence of 3-O-methylglucose or mannitol. Sugars other than D -glucose inhibited glucagon secretion only at much higher concentrations than those at which D -glucose was effective. Furthermore, although 7.5 mM D -glucose caused up to 80% inhibition, the effects of other sugars appeared to level off at only 50–60% inhibition. The inhibitory action of D -glucose or D -glyceraldehyde on glucagon secretion could not be overcome by L -arginine, but 3-O-methylglucose, mannoheptulose, 2-deoxy- D -glucose, iodoacetamide, theophylline, epinephrine and acetylcholine were effective. The insulin secretion in response to glucose was inhibited by the metabolic inhibitors used, whereas the B-cell response in the presence of glyceraldehyde was diminished by iodoacetamide only. Like D -glucose, a variety of other sugars markedly reduced the stimulatory effect of L -arginine in glucagon release. The results show that the suppression of glucagon secretion is not specific for D -glucose and not strongly connected on a stimulated insulin secretion.

By means of collagenase digestion and the Ficoll gradient separation technique, viable islets of Langerhans could be isolated from dog pancreata. The isolated islets were capable of secreting insulin after glucose stimulation. These islets of Langerhans were transplanted into the livers of diabetic dogs. We transplanted islets isolated from I donor pancreas for 1 kg body wt of the recipients. The dogs were made diabetic by subtotal pancreatectomy (80%) and two injections of 25 mg streptozotocin/kg body wt. In our experiments, we selected donor-recipient pairs by means of the mixed lymphocyte reaction macrophage electrophoretic migration inhibition (MLR-EM) test. In the group with a depression in the MLR-EM test of more than 15% (strong histoincompatibility), the mean survival time of the transplanted dogs was 46 ± 16 days. Another group of recipients with a depression of macrophage migration of less than 8% (weak histocompatibility) had a mean survival time of 135 ± 49 days after intraportal islet transplantation, and the blood glucose values could be normalized in this group for a period of 70 days. We found significant differences between both the groups in the glucose tolerance tests and in the IRI concentrations in the portal vein and in the vena cava superior. In the recipients, which received weakly histoincompatible islets, the IRI concentration in the superior vena cava was 64% of the normal value in the vena cava superior 4 weeks after intrahepatic islet transplantation. By means of the MLR-EM test, we were able to correlate inhibition with signs of rejection of the transplanted islets. Our experiments demonstrated that an allogeneic islet transplantation in diabetic dogs across a weakly histocompatible barrier can improve the results in comparison to the islet transplantation across a strongly histocompatible barrier. However, this typing maneuver alone is not able to prevent the islet rejection.

Summary Using immunofluorescence technique a positive reaction to insulin antiserum could be revealed in different parts of the CNS of Wistar rats and sand rats. The functional concept that nervous tissue is insulin-insensitive was called in question by investigations showing an influence of insulin on blood plasma glucose levels after an application of the hormone to the CNS ( Szabo and Szabo 1972). Recently, the presence of specific insulin receptors in the brain was demonstrated by radiochemical ( Havkankova et al. 1978) and immunocytochemical ( Pansky and Hatfield 1978) means. No data, however, are yet available concerning the occurrence of the hormone itself in the CNS. We present evidence for the existence in the rat CNS of a substance giving an immunological reaction with insulin-antiserum.

Glucose stimulates the uptake of 45Ca into (3-cell-rich pancreatic islets isolated from ob/ob-mice. The distribution of the incorporated radioactivity was analysed by labelling the organelles with 45Ca in their cellular environment. The radioactive content of the organelles was measured after homogenization and fractionation of the islets under conditions preventing 45Ca redistribution. The 45Ca taken up in response to glucose appeared essentially in the secretory granule fraction and in that enriched in mitochondria. Modification of the 45Ca loading procedure, involving reduction of the oxygen tension and incubation volume, resulted in the disappearance of the glucose effect on the mitochondrial fraction whereas part of the stimulatory effect on the secretory granules persisted. Buffering of calcium by the secretory granules and mitochondria may be important for regulating the cytoplasmic Ca2+ involved in stimulus-secretion coupling.

Using the PAP technique, we investigated the presence of neuron-specific enolase in the human fetal pancreas of 10, 12, and 14 weeks of gestational age. Neuron-specific enolase is present in the islet cells in the 10th week. Positive cells are situated mainly in duct epithelium. The number of cells with a positive reaction increases from the 12th to the 14th week. In the 14th week, they are clustered either near the ducts or between the acini. The numbers and localizations of the cells correspond to those obtained in previous studies with 4 basic islet cell types in the same material. The present results are a further proof that islet cells are biologically active during early fetal development.

Summary The hypothalamic and extrahypothalamic distribution of somatostatin-like immunoreactivity (SLI) was investigated in fed adult sand rats ( Psammomys obesus ) of both sexes using the immunofluorescence technique. Blood glucose and insulin concentrations were determined in these animals prior to decapitation. In a blind study, the amount of immunofluorescence of certain CNS areas and the glucose: Insulin ratio were compared and found to be connected: High amounts of SLI were detected in the dorsal hippocampus, in some hypothalamic nuclei and the median eminence of rats displaying low glucose levels. Sand rats with high blood glucose values did not show SLI in the hippocampal formation and the immunofluorescence of the circumventricular (hypothalamic) regions and the Emmentia mediana was drastically reduced. A possible correlation of SLI with insulin concentrations in the blood could not be revealed. The data obtained are discussed as a possible expression of a CNS influence on glucoregulation in this species.

Summary C-peptide/C-peptide-like immunoreactivity was shown to be present in the cytoplasm of the soma and the proximal part of apical dendrites of some pyramidal cells in the Neocortex (Gyrus precentralis) and Hippocampus of man. C-peptide (connecting peptide) is a metabolic product in insulin biosynthesis and its localization in neurons is a proof for extrapancreating insulin production.

Summary Glukagon-like immunoreactivity was demonstrated in different parts of rat and sand rat central nervous system by the indirect immunofluorescence method. In hyperglycemic animals the level of immunoreactive material was reduced to a great extent.

The effect of cyclic AMP on calcium movements in the pancreatic beta-cell was evaluated using an experimental approach based on in situ labelling of intracellular organelles of ob/ob-mouse islets with 45Ca. Whereas the glucose-stimulated 14Ca incorporation by mitochondria and secretory granules was increased under a condition known to reduce cyclic AMP (starvation), raised levels of this nucleotide (addition of 3-isobutyl-1-methylxanthine or N6,O2'-dibutyryl adenosine 3',5'-cyclic monophosphate) reduced the mitochondrial accumulation of 45Ca. Conditions with increased cyclic AMP were associated with a stimulated efflux of 45Ca from the secretory granules but not from the mitochondria. The microsomal fraction differed from both the mitochondrial and secretory granule fractions by accumulating more 45Ca after the addition of 3-isobutyl-1-methylxanthine. The results suggest that cyclic AMP potentiates glucose-stimulaated insulin release by increasing cytoplasmic Ca2+ at the expense of the calcium taken up by the organelles of the pancreatic beta-cells.

Summary The presence of glucagon-like immunoreactivity in nerve cells of different parts of the human brain was demonstrated by the indirect immunofluorescence technique. A bright fluorescent reaction was observed in the pyramidal cells of lamina V of the Neocortex. Less prominent concentrations of the glucagon-like material were detected in a few pyramidal cells of the Hippocampus and in some neurons of the Presubiculum and Subiculum. Within the Corpus amygdaloi-deum, only a few magnocellular neurons showed a positive reaction. The Hypothalamus was evidenced by a moderate, but widely distributed, reaction in magnocellular and medium-sized nerve cells in different nuclei (especially Nuc. ventromedialis and Nuc. arcuatus). A strong immunofluorescence was localized to some neurocytes in the Nuc. amibigus, and Nuc. n. hypoglossi. The Purkinje cells of the cerebellar cortex were free from immunoreactive material, but fluorescence occurred in some very small nerve cells of the Cerebellum (probably granular cells). A dependence of the strength of immunofluorescence of the time delay between autopsy and death is shown.