Habitat preferences of the Andean bear (Tremarctos ornatus) in the Bolivian Andes

Habitat preferences of the Andean bear Tremarctos ornatus were studied within two adjacent protected areas in the north-western Bolivian Andes. Standard transects measuring habitat variables and bear sign frequency were used spanning seven different vegetation types. Andean bears were present at 28 of 33 sampled sites and actively preferred high-elevation elfin forest and upper montane humid forests, and used high-elevation humid 'páramo' grasslands and middle montane humid forests according to their availability. Bears were absent from dry montane and Andean foothill forests and relative abundance was low in lower montane humid forests. Elevation and basal area of food items were the variables most closely related to the relative abundance.     

Gender difference in serum bisphenol A levels may be caused by liver UDP-glucuronosyltransferase activity in rats

Gender difference in human bisphenol A (BPA) concentrations was revealed by determining serum BPA. We studied the serum concentrations and the metabolism of BPA in rats by an HPLC system. Rat serum BPA concentrations were significantly higher in males (24.9+/-7.38 ng/ml, P=0.026, n=10) than in females (8.27+/-3.11 ng/ml, n=10), as in humans. The resultant enzyme reaction products of BPA glucuronidation in the rat liver microsomes fraction were analyzed by an HPLC system. The ratio of BPA glucuronidation in the microsome reaction was significantly higher (P=0.015) in female than in male rats. The mRNA expression of UDP-glucuronosyltransferase 2B1 (UGT2B1), an isoform of UGT related to BPA glucuronidation, in the rat liver was analyzed by a real-time quantitative RT-PCR. The relative expression level of UGT2B1 mRNA was significantly higher (P<0.001) in female than in male rat livers. The gender difference in serum BPA concentrations may be explained by the difference in clearance based on the UGT activities.     

The hyper-IgE syndrome is not caused by a microdeletion syndrome

The hyper-immunoglobulin E syndrome (HIES) is a rare primary immunodeficiency characterized by recurrent infections, elevated serum IgE-levels, and involvement of the soft- and bony tissues. We speculated that this complex disease may be caused by a microdeletion syndrome. We therefore analyzed 30 sporadic HIES patients for the presence of chromosomal imbalances using Affymetrix 50k XbaI and 23 of the 30 patients with the higher-resolution 250k StyI SNP mapping arrays. We detected only eight different copy number alterations in six patients with the 50k approach, and seven of these presented known polymorphic regions not associated with disease. However, one patient showed a unique gain on chromosome 20p. 250k array analysis identified this gain as a rare polymorphism segregating in the patient’s family, but not associated with the HIES phenotype. In addition, 265 known and novel copy number variants (CNVs) were identified with the 250k arrays, but no recurrent imbalances reminescent of a microdeletion syndrome were found. We aligned the identified CNVs with loci that have been associated with HIES or phenotypically overlapping syndromes. Doing so, a 2-Mb deletion spanning the PEPD gene on 19q13.11 was identified on one allele of one patient. Homozygous mutations in PEPD are responsible for the autosomal-recessive prolidase deficiency which resembles HIES in some aspects. Sequencing of the healthy allele, however, revealed a wild-type sequence. In summary, our results suggest that HIES is not likely to be a microdeletion syndrome. Dietmar Pfeifer and Cristina Woellner contributed equally to the work and are considered aequo loco.     

The Accumulation of Visceral Adipose Tissue may be Influenced by Intra-Abdominal Temperature

Despite the established link between visceral obesity and major chronic diseases, little is known about physiologic factors that directly and specifically lead to the accumulation of visceral fat. I hypothesize that reduced intra-abdominal temperature might be a physical factor underlying the partitioning of adipose tissue to the intra-abdominal region rather than the periphery. The hypothesis is supported by biochemical reports that rat and bovine lipoprotein lipase have increased activity when incubated at lower temperatures. Persons exercising in cool water have been found to preserve subcutaneous fat whereas comparable exercise without local cooling results in subcutaneous fat loss. Pima Indians, a group that commonly acquires extreme levels of visceral fat, have been found to have lower intraabdominal temperatures during sleep than weight-matched European-Americans. In a study of four young men and four young women, I have noted that mean intra-abdominal basal temperatures were higher for women than men (36.51 ± 0.18°C vs. 35.91 ± 0.11°C; p = .0014). Since the men are more likely to acquire visceral obesity at later age, this also provides support for my hypothesis. Investigators might wish to examine further the temperature dependence of adipose-tissue lipoprotein lipase, the temperature variation between sites of adipose tissue, and the effects of foods, physical activities, smoking and drugs on localized body temperature.     

Complex relation between triazine-susceptible phenotype and genotype in the weed Senecio vulgaris may be caused by chloroplast DNA polymorphism

The weed Senecio vulgaris acquired high levels of resistance to triazine herbicides soon after the latter’s introduction. As in most weeds, triazine resistance is conferred by a point mutation in the chloroplast psbA gene that negatively affects the fitness of its carrier. To assess levels of triazine resistance in S. vulgaris field populations, we adopted a PCR-RFLP-based molecular diagnostic test recently developed for the triazine resistance-conferring region of the psbA gene of other weeds, including Brassica napus, Chenopodium spp. and Amaranthus spp., and compared these molecular results to the phenotypic response after triazine application. A highly significant linear correlation was found between phytotoxic symptoms and biomass reduction. Variability in phenotypic response was not only found between populations or inbred lines of S. vulgaris but also within replicates of the same inbred line. No clear relationship, however, was found between the DNA restriction pattern and the phenotypic response to triazine application, thereby throwing doubt on the use of such molecular diagnostic tests to track triazine resistance in S. vulgaris. Our results indicate that the chloroplast genome of S. vulgaris is polymorphic and that the level of polymorphism may be variable within single leaves of individual plants. We discuss the possible genetic basis of this polymorphism and its consequence for the acquisition and inheritance of chloroplast-based traits. Received: 28 December 1998 / Accepted: 20 February 1999     

Encephalopathy caused by ablation of very long acyl chain ceramide synthesis may be largely due to reduced galactosylceramide levels

Sphingolipids (SLs) act as signaling molecules and as structural components in both neuronal cells and myelin. We now characterize the biochemical, histological, and behavioral abnormalities in the brain of a mouse lacking very long acyl (C22-C24) chain SLs. This mouse, which is defective in the ability to synthesize C22-C24-SLs due to ablation of ceramide synthase 2, has reduced levels of galactosylceramide (GalCer), a major component of myelin, and in particular reduced levels of non-hydroxy-C22-C24-GalCer and 2-hydroxy-C22-C24- GalCer. Noteworthy brain lesions develop with a time course consistent with a vital role for C22-C24-GalCer in myelin stability. Myelin degeneration and detachment was observed as was abnormal motor behavior originating from a subcortical region. Additional abnormalities included bilateral and symmetrical vacuolization and gliosis in specific brain areas, which corresponded to some extent to the pattern of ceramide synthase 2 expression, with astrogliosis considerably more pronounced than microglial activation. Unexpectedly, unidentified storage materials were detected in lysosomes of astrocytes, reminiscent of the accumulation that occurs in lysosomal storage disorders. Together, our data demonstrate a key role in the brain for SLs containing very long acyl chains and in particular GalCer with a reduction in their levels leading to distinctive morphological abnormalities in defined brain regions.     

Differences in preterm and term milk fatty acid compositions may be caused by the different hormonal milieu of early parturition

Introduction

The hormonal milieus of pregnancy and lactation are driving forces of nutrient fluxes supporting infant growth and development. The decrease of insulin sensitivity with compensatory hyperinsulinemia with advancing gestation, causes adipose tissue lipolysis and hepatic de novo lipogenesis (DNL).

Subjects and methods

We compared fatty acid (FA) contents and FA-indices for enzyme activities between preterm (28–36 weeks) and term (37–42) milks, and between colostrum (2–5 days), transitional (6–15) and mature (16–56) milks. We interpreted FA differences between preterm and term milks, and their changes with lactation, in terms of the well known decrease of insulin sensitivity during gestation and its subsequent postpartum restoration, respectively.

Results

Compared with term colostrum, preterm colostrum contained higher indices of DNL in the breast (DNL-breast) and medium chain saturated-FA (MCSAFA), and lower DNL-liver and monounsaturated-FA (MUFA). Preterm milk also had higher docosahexaenoic acid (DHA) in colostrum and transitional milk and higher arachidonic acid (AA) in mature milk. Most preterm-term differences vanished with advancing lactation. In both preterm and term milks, DNL-breast and MCSAFA increased with advancing lactation, while DNL-liver, MUFA, long chain SAFA and AA decreased. DHA decreased in term milk. MUFA was inversely related to MCSAFA in all samples, correlated inversely with PUFA in colostrum and transitional milks, but positively in mature milk. MCSAFA correlated inversely with PUFA in mature milk.

Conclusion

Higher maternal insulin sensitivity at preterm birth may be the cause of lower MUFA (a proxy for DNL-liver) and higher MCSAFA (a proxy for DNL-breast) in preterm colostrum, compared with term colostrum. Restoring insulin sensitivity after delivery may be an important driving force for milk FA-changes in early lactation.     

The exceptional longevity of the naked mole‐rat may be explained by mitochondrial antioxidant defenses

Naked mole‐rats (NMRs) are mouse‐sized mammals that exhibit an exceptionally long lifespan (>30 vs. <4 years for mice), and resist aging‐related pathologies such as cardiovascular and pulmonary diseases, cancer, and neurodegeneration. However, the mechanisms underlying this exceptional longevity and disease resistance remain poorly understood. The oxidative stress theory of aging posits that (a) senescence results from the accumulation of oxidative damage inflicted by reactive oxygen species (ROS) of mitochondrial origin, and (b) mitochondria of long‐lived species produce less ROS than do mitochondria of short‐lived species. However, comparative studies over the past 28 years have produced equivocal results supporting this latter prediction. We hypothesized that, rather than differences in ROS generation, the capacity of mitochondria to consume ROS might distinguish long‐lived species from short‐lived species. To test this hypothesis, we compared mitochondrial production and consumption of hydrogen peroxide (H₂O₂; as a proxy of overall ROS metabolism) between NMR and mouse skeletal muscle and heart. We found that the two species had comparable rates of mitochondrial H₂O₂ generation in both tissues; however, the capacity of mitochondria to consume ROS was markedly greater in NMRs. Specifically, maximal observed consumption rates were approximately two and fivefold greater in NMRs than in mice, for skeletal muscle and heart, respectively. Our results indicate that differences in matrix ROS detoxification capacity between species may contribute to their divergence in lifespan.     

The specificity of carboxypeptidase Y may be altered by changing the hydrophobicity of the S'1 binding pocket.

The S'1 binding pocket of carboxypeptidase Y is hydrophobic, spacious, and open to solvent, and the enzyme exhibits a preference for hydrophobic P'1 amino acid residues. Leu272 and Ser297, situated at the rim of the pocket, and Leu267, slightly further away, have been substituted by site-directed mutagenesis. The mutant enzymes have been characterized kinetically with respect to their P'1 substrate preferences using the substrate series FA-Ala-Xaa-OH (Xaa = Leu, Glu, Lys, or Arg) and FA-Phe-Xaa-OH (Xaa = Ala, Val, or Leu). The results reveal that hydrophobic P'1 residues bind in the vicinity of residue 272 while positively charged P'1 residues interact with Ser297. Introduction of Asp or Glu at position 267 greatly reduced the activity toward hydrophobic P'1 residues (Leu) and increased the activity two- to three-fold for the hydrolysis of substrates with Lys or Arg in P'1. Negatively charged substituents at position 272 reduced the activity toward hydrophobic P'1 residues even more, but without increasing the activity toward positively charged P'1 residues. The mutant enzyme L267D + L272D was found to have a preference for substrates with C-terminal basic amino acid residues. The opposite situation, where the positively charged Lys or Arg were introduced at one of the positions 267, 272, or 297, did not increase the rather low activity toward substrates with Glu in the P'1 position but greatly reduced the activity toward substrates with C-terminal Lys or Arg due to electrostatic repulsion. The characterized mutant enzymes exhibit various specificities, which may be useful in C-terminal amino acid sequence determinations.     

The protective role of localized nitric oxide production during inflammation may be mediated by the heme oxygenase-1/carbon monoxide pathway

Nitric oxide (NO) is an important part of the host defense mechanism; however, it displays both pro- and anti-inflammatory properties depending on its location and concentration. Importantly, excessive or inappropriate NO production can cause tissue damage. Systemic and local administration of NO synthase (NOS) inhibitors ameliorates and may exacerbate the inflammatory response, respectively. Here, we used a carrageenan-induced pleurisy model of acute inflammation in rats to confirm the location-dependent effects of NO and investigate the underlying mechanisms. As expected, localized suppression of NO production exacerbated inflammation, as evidenced by increased pleural exudate volumes and leukocyte counts and enhanced activity of enzymes related to oxidative stress. In contrast, local NO supplementation reduced leukocyte infiltration, vascular permeability, and the activity of oxidative stress-related enzymes. Interestingly, inhibition of heme oxygenase-1 (HO-1) reversed the anti-inflammatory effects of localized NO production, while the addition of hemin (HO-1 substrate) or carbon monoxide (CO; HO-1 metabolite) decreased leukocyte migration and exudation. Together, these findings confirm a protective role for NO at the inflammatory site, which appears to be mediated via NOS induction of the HO-1/CO pathway. Thus, NO supplementation may be a potential new treatment for oxidative stress-associated inflammatory diseases.     

The spectrum of 4q- syndrome illustrated by a case series

Deletions of the long arm of chromosome 4 detectable by cytogenetic analysis (standard karyotyping), fluorescent in situ hybridisation (FISH), multiplex ligation-dependent probe amplification (MLPA) or comparative genomic hybridisation (CGH) cause 4q- syndrome. Here we describe 3 cases of 4q- syndrome which demonstrate the variations in clinical presentation, diagnosis and prognosis observed in this condition. Patient 1 was a female foetus diagnosed with del(4)(q33) following chorionic villus sampling (CVS) at 14weeks, and the pregnancy was terminated at 18weeks. Patient 2 was a 5-month-old boy with del(4)(q31.3) and complex congenital heart disease. He also had a duplication of chromosome 6p and died of cardiac failure. Patient 3 is a 2-year-old girl with mild dysmorphic features and an interstitial deletion del(4)(q22.1q23). She has no major malformations and only slight developmental delay.     

Somatic homologous recombination in planta: The recombination frequency is dependent on the allelic state of recombining sequences and may be influenced by genomic position effects

The Escherichia coli sodA gene encoding the antioxidant enzyme Mn-containing superoxide dismutase (MnSOD), was cloned in the expression vector pMG36e. This vector has a multiple cloning site down-stream of a promoter and Shine-Dalgarno sequences derived from Lactococcus. The protein-coding region of sodA from E. coli was amplified by the polymerase chain reaction, using a thermocycler and Taq DNA polymerase before cloning into pMG36e. When introduced into E. coli, the recombinant plasmid expressed the predicted fusion protein, both in the presence and absence of oxygen. The expression of the fusion protein in E. coli was verified by SOD assays, activity gels and Western blots. The recombinant plasmid was also introduced into Lactococcus lactis, which contains a resident SOD, and into Lactobacillus gasseri, which is devoid of SOD. Transformed lactococci expressed an active SodA fusion protein plus an active hybrid protein composed of subunits of the Lactococcus and the recombinant E. coli enzymes. Transformants of L. gasseri expressed only the fusion SodA protein, which was enzymatically active.