Direct Comparisons of 2D and 3D Dental Microwear Proxies in Extant Herbivorous and Carnivorous Mammals

The analysis of dental microwear is commonly used by paleontologists and anthropologists to clarify the diets of extinct species, including herbivorous and carnivorous mammals. Currently, there are numerous methods employed to quantify dental microwear, varying in the types of microscopes used, magnifications, and the characterization of wear in both two dimensions and three dimensions. Results from dental microwear studies utilizing different methods are not directly comparable and human quantification of wear features (e.g., pits and scratches) introduces interobserver error, with higher error being produced by less experienced individuals. Dental microwear texture analysis (DMTA), which analyzes microwear features in three dimensions, alleviates some of the problems surrounding two-dimensional microwear methods by reducing observer bias. Here, we assess the accuracy and comparability within and between 2D and 3D dental microwear analyses in herbivorous and carnivorous mammals at the same magnification. Specifically, we compare observer-generated 2D microwear data from photosimulations of the identical scanned areas of DMTA in extant African bovids and carnivorans using a scanning white light confocal microscope at 100x magnification. Using this magnification, dental microwear features quantified in 2D were able to separate grazing and frugivorous bovids using scratch frequency; however, DMTA variables were better able to discriminate between disparate dietary niches in both carnivorous and herbivorous mammals. Further, results demonstrate significant interobserver differences in 2D microwear data, with the microwear index remaining the least variable between experienced observers, consistent with prior research. Overall, our results highlight the importance of reducing observer error and analyzing dental microwear in three dimensions in order to consistently interpret diets accurately.     

Ca-dependent slow action potentials in human skeletal muscle

Slow Ca-action potentials (CaAP) were studied in normal human skeletal muscle fibers obtained during surgery (fibers with both ends cut). Control studies also were carried out with intact as well as cut rat skeletal muscle fibers. Experiments were performed in hypertonic Cl-free saline with 10 or 84 mM Ca and K-channel blockers; muscles were preincubated in a saline containing Cs and tetraethylammonium. A current-clamp technique with two intracellular microelectrodes was used. In human muscle, 14.5% of the fibers showed fully developed CaAPs, 21% displayed nonregenerative Ca responses, and 64.5% showed only passive responses; CaAPs were never observed in 10 mM Ca. In rat muscle, nearly 90% of the fibers showed CaAPs, which were not affected by the cut-end condition. Human and rat muscle fibers had similar membrane potential and conductance in the resting state. In human muscle (22-32 degrees C, 84 mM Ca), the threshold and peak potential during a CaAP were +26 +/- 6 mV and +70 +/- 3 mV, respectively, and the duration measured at threshold level was 1.7 +/- 0.5 sec. In rat muscle, the duration was four times longer. During a CaAP, membrane conductance was assumed to be a leak conductance in parallel with a Ca and a K conductance. In human muscle (22-32 degrees C, 84 mM Ca, 40 micron fiber diameter), values were 0.4 +/- 0.1 microS, 1.1 +/- 0.7 microS, and 0.9 +/- 0.4 microS, respectively. Rat muscle (22-24 degrees C, 84 mM Ca) showed leak and K conductances similar to those found in human fibers. Ca-conductance in rat muscle was double the values obtained in human muscle fibers.     

Structure of the sugar-phosphate moiety of lipid A from lipooligosaccharide of Neisseria meningitidis group B,strain BC5S No. 125

On the basis of chemical and NMR data the partial structure of lipid A from lipooligosaccharide (LOS) of Neisseria meningitidis group B, strain BC₅S No 125 was established. Lipid A consisted of disaccharide 2-deoxy-6-O-[2-deoxy-2-(3-hydroxytetradecanoylamino)--gluco-pyranosyl]-2-(3-hydroxytetradecanoylamino)--glucopyranose carrying the -(2-aminoethyl)pyrophosphate residue at 0–4 and the pyrophosphate or phosphate residue at 0–1. On hydrolysis of the acidic form of LOS with 1% acetic acid the substituent at 0–1 was practically completely removed whereas that at 0–4 was stable. The analogous hydrolysis of the Mg-salt of LOS was accompanied by splitting off the pyrophosphate linkage in the substituent at 0–4. Hydrolysis of LOS at pH 4.5 in the presence of SDS led mainly to a lipid A preparation retaining both pyrophosphate residues.Abbreviations KDO 2-keto-3-deoxyoctulosonic acid - LA-I, LA-II preparations of lipid A - LOS lipooligosaccharide - LOS-H⁺ the acidic form of LOS - OS oligosaccharide - TLC thin-layer chromatography - GLC-MS gas-liquid chromatography/mass spectrometry     

Molecular genetic studies of Creutzfeldt-Jakob disease

Genetic study of over 200 cases of Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker disease (GSS), fatal familial insomnia (FFI), and kuru have brought a reliable body of evidence that the familial forms of CJD and all known cases of GSS and FFI are linked to germline mutations in the coding region of the PRNP gene on chromosome 20, either point substitutions or expansion of the number of repeat units. No pathogenic mutations have so far been found in sporadic or infectious forms of CJD, although there are features of genetic predisposition in iatrogenic CJD and kuru. In FFI and familial CJD, clinically and pathologically distinct syndromes that are both linked to the 178^Asp→Asn substitution, phenotypic expression is dependent on a polymorphism at codon 129. Synthetic peptides homologous to several regions of PrP spontaneously form insoluble amyloid fibrils with unique morphological characteristics and polymerization tendencies. Peptides homologous to mutated regions of PrP exhibit enhanced fibrilogenic properties and, if mixed with the wild-type peptide, produce even more abundant and larger fibrous aggregates. A similar process in vivo may lead to amyloid accumulation and disease, and transmission of “baby fibrils” may induce disease in other hosts.     

Possibility of analytical application of the partition in aqueous biphasic polymeric systems technique

The partition behaviour of a number of ionic and nonionic surface-active substances in the dextran-polyethylene glycol system was examined. The strictly linear dependence of the logarithm of the partition coefficient on the alkyl chain length for a homologous series of nonionic surfactants provides a measure of the difference in the relative hydrophobicity between the two phases of the system, in terms of the free energy of transfer of a CH₂ group from the bottom phase to the top phase of the system. This difference is found to be altered in the presence of NaCl or KCl depending on the salt concentration. It is concluded that the influence of the salt composition of the system on the distributed solutes' behaviour may be due to the effect of the ions on the hydrophobicity difference between the phases.The partition of ionic amphiphiles is found to be dependent on the relative hydrophobicity of the compounds as well as on their charge. It is shown that at salt concentrations up to about 0.1 M NaCl the charged solute partition is determined by its charge as well as its relative hydrophobicity, in the presence of 0.1–0.2 M NaCl the substance distribution is highly dependent on its charge and slightly on its lipophility. At the salt concentrations above 0.2 M the solute partition is determined just by its hydrophobic character and seems to be totally independent of its charge. It is concluded that the partition technique can be used for analytical purposes. The method seems to be unique in providing quantitative information on the amphiphilic surface properties of the solutes being partitioned.     

ACTIVITY OF ALDEHYDE DEHYDROGENASE, ALDEHYDE REDUCTASE, AND ACETYLCHOLINE ESTERASE IN STRITATUM OF RATS BEARING ELECTROLYTIC LESIONS OF THE MEDIAL FOREBRAIN BUNDLE

A number of enzymes have been measured in the striatum of rats in which the dopamine-containing nerve terminals had been unilaterally destroyed by means of unipolar electrolytic lesions of the medial fore-brain bundle. Fourteen and 28 days after such lesions the tyrosine hydroxylase activity of the striatum was reduced to immeasurably low values, but neither aldehyde dehydrogenase, aldehyde reductase, nor acetylcholine esterase was affected when compared with the striatum from the intact side of the same rat or with those from control rats. These results indicate that in the rat the 3 enzymes are not localized with tyrosine hydroxylase, in the dopaminergic nerve terminals of the striatum. This conclusion is supported by a study of the subcellular localization of aldehyde dehydrogenase in rat brain. This enzyme is distributed between the cytosol and the particulate fraction of brain homogenates separated by centrifugal techniques. with no exceptionally high concentration of the enzyme in the synaptosomal fraction. Because neither of the enzymes of post-deaminative catabolism of dopamine is concentrated in the dopaminergic nerve terminals of the striatum of the rat, it is proposed that in this species the amine is not necessarily taken up by the nerve terminals prior to catabolism.     

Early Life Stress and Post-Weaning High Fat Diet Alter Tyrosine Hydroxylase Regulation and AT1 Receptor Expression in the Adrenal Gland in a Sex Dependent Manner

Previous studies have shown that early life stress induced by maternal separation or non-handling can lead to behavioural deficits in rats and that these deficits can be alleviated by providing palatable cafeteria high-fat diet (HFD). In these studies we investigated the effects of maternal separation or non-handling and HFD on tyrosine hydroxylase (TH) protein and TH phosphorylation at Ser40 (pSer40TH) and the expression of angiotensin II receptor type 1 (AT1R) protein in the adrenal gland as markers of sympatho-adrenomedullary activation. After littering, Sprague–Dawley rats were assigned to short maternal separation, S15 (15 min), prolonged maternal separation, S180 (180 min) daily from postnatal days 2–14 or were non-handled (NH) until weaning. Siblings were exposed to HFD or chow from day 21 until 19 weeks when adrenals were harvested. Maternal separation and non-handling had no effects on adrenal TH protein in both sexes. We found an effect of HFD only in the females; HFD significantly increased TH levels in NH rats and pSer40TH in S180 rats (relative to corresponding chow-fed groups), but had no effect on AT1R expression in any group. In contrast, in male rats HFD had no effect on TH protein levels, but significantly increased pSer40TH across all treatment groups. There was no effect of HFD on AT1R expression in male rats; however, maternal separation (for 15 or 180 min) caused significant increases in AT1R expression (relative to NH group regardless of diet). This is the first study to report that early life stress and diet modulate TH protein, pSer40TH and AT1R protein levels in the adrenal gland in a sex dependent manner. These results are interpreted in respect to the potential adverse effects that these changes in the adrenal gland may have in males and females in adult life.     

Comparative Study of Accumulation of Two Potato Virus X Strains Differing in Virulence,Hydrolase Activity and Morphological Abnormalities in Datura stramonium L. Leaves

In young systemically infected leaves of Datura stramonium L., a severe strain of Potato virus X (PVX) accumulated to a lower degree than a mild strain. Infected leaves had increased protease and RNase activities in comparison with those of healthy controls. The highest hydrolase activities were found in leaves infected with the severe strain. Negative‐staining electron microscopy of dips from the infected leaves indicated that PVX virions underwent destructive changes, which resulted in the appearance of abnormal (swollen and ‘thin’) particles. Immuno‐electron microscopic assays showed that thin PVX particles, in contrast to those of normal diameter, lost the ability to bind with specific antiserum. The relative number of thin virions in leaves infected with the severe PVX strain was considerably higher than in leaves infected with the mild strain. This shows that a correlation exists between increased protease activity and intracellular destruction of virions. In abnormal virions, the viral RNA appears to be available for RNase attack. Therefore, it seems that high RNase activity together with increased generation of abnormal virions in the leaves infected with the severe strain promote inactivation of the viral RNA with RNase. We suppose that the enhanced hydrolase activities in the leaves infected with severe PVX strain, on the one hand, limit viral accumulation and thus play a defensive role and, on the other hand, cause considerable intracellular pathological changes resulting in severe symptoms.