Effects of streptozotocin-induced diabetes on fetal development of the rat

The purpose of this study was to determine whether or not in rats with experimentally induced diabetes there is an increased frequency of congenital malformations; data in the literature are not consistent on this point. Virgin CD females rats were injected with 40-50 mg/kg streptozotocin (Stz) before mating (SIBM group) or on the first day of pregnancy (SI1). Both SIBM and SI1 females were divided into two groups according to their blood glucose levels: severely diabetic (SD, greater than 300 mg%) and mildly diabetic (MD, 120-250 mg%). Food and water consumption by the control and MD groups were the same, but the SD females developed polyphagia, polyuria, and polydypsia, which continued to increase throughout pregnancy, as did the blood glucose levels. All the MD females mated and carried to term. In SD females both frequency of mating and fertility were only slightly lower than in the controls. All the females were killed on the 21st day of pregnancy. Pre- and postimplantation losses were the same for diabetic and control rats, but SIBM-SD females ovulated less than other groups. Weights of fetuses of SD dams were lower and blood sugar levels higher than those of the other groups. The placentas of SD rats were significantly heavier and there was cystic degeneration of spongiosa. The incidence of major malformations was minimal (approximately 2%) in fetuses of SD females and there were none at all in controls or MD females. In conclusion, our data are in agreement with those of other investigators who have found that rats with experimentally induced diabetes have smaller fetuses and increased placental weight.(ABSTRACT TRUNCATED AT 250 WORDS)     

HPLC analysis of free amino acids and amino acids of total proteins in cultured cells: an application to the study of rat Sertoli cell protein metabolism.

A simple, rapid and, sensitive HPLC method, coupled with fluorometric detection, has been worked out and employed to determine the intracellular free amino acid concentrations and the amino acid composition of total proteins in rat Sertoli cell primary culture. Sertoli cells were isolated enzymatically from testes of 20- and 28-day-old rats and cultured at 32 degrees C in Eagle's minimum essential medium. On the second day of culture, cell monolayers were quickly rinsed with ice-cold saline, immediately frozen in liquid nitrogen, accurately harvested, and homogenized in 10% trichloroacetic acid. Tissue free amino acids were determined in the acidic soluble fraction following neutralization, while the precipitate was hydrolyzed for the evaluation of the fractional content of amino acids into total proteins. Amino acid samples were derivatized with o-phthaldialdehyde/3-mercaptopropionic acid and resolved by a linear one-step acetonitrile gradient in 12.5 mM sodium phosphate buffer, pH 7.2, employing a 5-microns particle size reversed-phase column. Fluorescence was monitored with excitation at 330 nm and emission at 450 nm. Under these conditions all major physiological amino acids could be satisfactory separated, identified, and subsequently quantified with the aid of standards. The run time was about 50 min; the linearity was excellent over a large range of concentrations (1-800 pmol) and the lower limit of sensitivity appeared to be 0.5 pmol. This method permits us to demonstrate age-dependent modifications in the intracellular amino acid pool and to adequately evaluate the process of protein synthesis in cultured Sertoli cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Interaction of gibberellic and indole-3-acetic acid on root formation in pea (Pisum sativum L.) epicotyl cuttings

Indole-3-acetic acid (IAA) strongly enhanced rooting of etiolated pea epicotyl cuttings while gibberellic acid (GA₃) enhanced rooting only slightly. The promoting effects of the hormones appeared not until 14 d after the onset of treatment. When GA₃ and IAA were applied together, the initiation of rooting started already after 6 d after onset of treatment. It is suggested that gibberellin plays an important role, in combination with auxin, in the initiation of root formation in Pisum cuttings.Abbreviations IAA Indole-3-acetic acid - GA₃ Gibberellic acid     

Community mean traits as additional indicators to monitor effects of land-use intensity on grassland plant diversity

Semi-natural grasslands, biodiversity hotspots in Central-Europe, suffer from the cessation of traditional land-use. Amount and intensity of these changes challenge current monitoring frameworks typically based on classic indicators such as selected target species or diversity indices. Indicators based on plant functional traits provide an interesting extension since they reflect ecological strategies at individual and ecological processes at community levels. They typically show convergent responses to gradients of land-use intensity over scales and regions, are more directly related to environmental drivers than diversity components themselves and enable detecting directional changes in whole community dynamics. However, probably due to their labor- and cost intensive assessment in the field, they have been rarely applied as indicators so far.Here we suggest overcoming these limitations by calculating indicators with plant traits derived from online accessible databases. Aiming to provide a minimal trait set to monitor effects of land-use intensification on plant diversity we investigated relationships between 12 community mean traits, 2 diversity indices and 6 predictors of land-use intensity within grassland communities of 3 different regions in Germany (part of the German ‘Biodiversity Exploratory’ research network). By standardization of traits and diversity measures, use of null models and linear mixed models we confirmed (i) strong links between functional community composition and plant diversity, (ii) that traits are closely related to land-use intensity, and (iii) that functional indicators are equally, or even more sensitive to land-use intensity than traditional diversity indices. The deduced trait set consisted of 5 traits, i.e., specific leaf area (SLA), leaf dry matter content (LDMC), seed release height, leaf distribution, and onset of flowering. These database derived traits enable the early detection of changes in community structure indicative for future diversity loss. As an addition to current monitoring measures they allow to better link environmental drivers to processes controlling community dynamics.     

Up in the Tree – The Overlooked Richness of Bryophytes and Lichens in Tree Crowns

Assessing diversity is among the major tasks in ecology and conservation science. In ecological and conservation studies, epiphytic cryptogams are usually sampled up to accessible heights in forests. Thus, their diversity, especially of canopy specialists, likely is underestimated. If the proportion of those species differs among forest types, plot-based diversity assessments are biased and may result in misleading conservation recommendations. We sampled bryophytes and lichens in 30 forest plots of 20 m × 20 m in three German regions, considering all substrates, and including epiphytic litter fall. First, the sampling of epiphytic species was restricted to the lower 2 m of trees and shrubs. Then, on one representative tree per plot, we additionally recorded epiphytic species in the crown, using tree climbing techniques. Per tree, on average 54% of lichen and 20% of bryophyte species were overlooked if the crown was not been included. After sampling all substrates per plot, including the bark of all shrubs and trees, still 38% of the lichen and 4% of the bryophyte species were overlooked if the tree crown of the sampled tree was not included. The number of overlooked lichen species varied strongly among regions. Furthermore, the number of overlooked bryophyte and lichen species per plot was higher in European beech than in coniferous stands and increased with increasing diameter at breast height of the sampled tree. Thus, our results indicate a bias of comparative studies which might have led to misleading conservation recommendations of plot-based diversity assessments.     

Quinones bearing non-steroidal anti-inflammatory fragments as multitarget ligands for Alzheimer’s disease

The anti-amyloid properties shared by several quinones inspired the design of a new series of hybrids derived from the multi-target drug candidate memoquin (1). The hybrids consist of a central benzoquinone core and a fragment taken from non-steroidal anti-inflammatory drugs, connected through polyamine linkers. The new hybrids retain the potent anti-aggregating activity of the parent 1, while exhibiting micromolar AChE inhibitory activities. Remarkably, 2, 4, (R)-6 and (S)-6 were Aβ aggregation inhibitors even more potent than 1. The balanced amyloid/cholinesterase inhibitory profile is an added value that makes the present series of compounds promising leads against Alzheimer’s disease.     

Gene expression in Xenopus laevis embryos after Triadimefon exposure

The triazole derivative Triadimefon (FON) is a systemic fungicide used to control powdery mildews, rusts, and other fungal pests. Some data have already been published about the teratogenic activity of this compound: craniofacial malformations were found in mouse, rat, and Xenopus laevis embryos exposed to FON. These alterations were correlated to defective branchial arch development possibly caused by abnormal neural crest cell (NCC) migration into the branchial mesenchyme. As the migration of NCCs is controlled by the HOX code and by an anteroposterior retinoic acid (RA) gradient, we analyzed the expression of CYP26, a key enzyme in RA metabolism, following FON exposure. The increased expression of this gene and the ability of citral (a RA inhibitor) to reduce the teratogenic effects of the fungicide support the notion that endogenous RA is involved in the mechanism of action of FON. Moreover, by in situ hybridization, we studied the effects of FON exposure at gastrula stage on the expression of some genes involved in craniofacial development, hindbrain patterning, and NCC migration. We observed abnormal localization of xCRABP, Hoxa2 and Xbap signal expression at the level of migrating NCC domains, whereas in the hindbrain, we did not find any alteration in Krox20 and Hoxa2 expression.     

Platinum toxicity and gene expression in Xenopus embryos: analysis by FETAX and differential display

Since the level of platinum in the environment is destined to increase, because of its use in vehicle catalytic converters, the toxicity of platinum needs further investigation. In this study, the frog embryo teratogenesis assay-Xenopus (FETAX) was used to compare the embryotoxicity and teratogenicity of two common platinum species, (NH4)2PtCl4 and (NH4)2PtCl6. The uptake rates of the two platinum species were studied, and also their effects on the expression of genes encoding metallothionein and heat-shock protein 70, which are known to be induced by several stress factors. In addition, the differential display technique was used to search for genes that were specifically induced by platinum. A gene for the type I collagen alpha-chain and a novel gene were identified.