Indices of environmental temperatures for primates in open habitats

Studies of thermoregulation in primates are under-represented in the literature, although there is sufficient evidence to suggest that temperature represents an important ecological constraint. One of the problems in examining thermoregulation in primates, however, is the difficulty in quantifying the thermal environment, since shade temperatures, solar radiation, humidity and wind speed all serve to alter an animals perceived temperature. Since animals respond to their perceived temperature, we need methods to account for each of these factors, both individually and collectively, if we are to understand the integrated impact of the thermal environment on primates. Here, we present a review of some thermal indices currently available. Black bulb temperatures can account for the effect of solar radiation, with wind chill equivalent temperatures and the heat index providing quantifiable estimates of the relative impact of wind speed and humidity, respectively. We present three potential indices of the perceived environmental temperature (PET) that account for the combined impact of solar radiation, humidity and wind speed on temperature, and perform a preliminary test of all of the climatic indices against behavioural data from a field study of chacma baboons (Papio cynocephalus ursinus) at De Hoop Nature Reserve, South Africa. One measure of the perceived environmental temperature, PET2, is an effective thermal index, since it enters the models for feeding and resting behaviour, and also accounts for levels of allogrooming. Solar radiation intensity is an important factor underlying these relationships, although the wind chill equivalent temperature and humidity enter the models for other behaviours. Future studies should thus be mindful of the impact of each of these elements of the thermal environment. A detailed understanding of primate thermoregulation will only come with the development of biophysical models of the thermal characteristics of the species and its environment. Until such developments, however, the indices presented here should permit a more detailed examination of the thermal environment, allowing thermoregulation to be given greater precedence in future studies of primate behaviour.     

Habitual cave use and thermoregulation in chacma baboons (Papio hamadryas ursinus)

The willingness to utilise caves as shelters is held to have been important to early humans but dependent on pyrotechnology. Despite anecdotal evidence that non-human primates will also exploit caves there has as yet been no detailed account of such exploitation or of the reasons underlying it. Here we provide the first such data, on the frequency and patterning of the use of an underground cave system by baboons (Papio hamadryas)—and show that usage is determined, at least in part, by above-ground temperatures.     

Effects of tylosin use on erythromycin resistance in enterococci isolated from swine

The effect of tylosin on erythromycin-resistant enterococci was examined on three farms; farm A used tylosin for growth promotion, farm B used tylosin for treatment of disease, and farm C did not use tylosin for either growth promotion or disease treatment. A total of 1,187 enterococci were isolated from gestation, farrowing, suckling, nursery, and finishing swine from the farms. From a subset of those isolates (n = 662), 59% (124 out of 208), 28% (80 out of 281), and 2% (4 out of 170) were resistant to erythromycin (MIC >/= 8 microg/ml) from farms A, B, and C, respectively. PCR analysis and Southern blotting revealed that 95% (65 out of 68) of isolates chosen from all three farms for further study were positive for ermB, but all were negative for ermA and ermC. By using Southern blotting, ermB was localized to the chromosome in 56 of the isolates while 9 isolates from farms A and B contained ermB on two similar-sized plasmid bands (12 to 16 kb). Pulsed-field gel electrophoresis revealed that the isolates were genetically diverse and represented a heterogeneous population of enterococci. This study suggests that although there was resistance to a greater number of enterococcal isolates on a farm where tylosin was used as a growth promotant, resistant enterococci also existed on a farm where no antimicrobial agents were used.     

Lipoprotein kinetics in the metabolic syndrome: pathophysiological and therapeutic lessons from stable isotope studies

Dyslipoproteinaemia is a cardinal feature of the metabolic syndrome that accelerates atherosclerosis. It is usually characterised by high plasma concentrations of triglyceride-rich and apolipoprotein (apo) B-containing lipoproteins, with depressed concentrations of high-density lipoprotein (HDL). Dysregulation of lipoprotein metabolism in these subjects may be due to a combination of overproduction of very-low-density lipoprotein (VLDL) apoB-100, decreased catabolism of apoB-containing particles, and increased catabolism of HDL apoA-I particles. These abnormalities may be consequent on a global metabolic effect of insulin resistance that increases the flux of fatty acids from adipose tissue to the liver, the accumulation of fat in the liver, the increased hepatic secretion of VLDL-triglycerides and the remodelling of both low-density lipoprotein (LDL) and HDL particles in the circulation; perturbations in lipolytic enzymes and lipid transfer proteins contribute to the dyslipidaemia. Our in vivo understanding of the kinetic defects in lipoprotein metabolism in the metabolic syndrome has been chiefly achieved by ongoing developments in the use of stable isotope tracers and mathematical modelling. Knowledge of the pathophysiology of lipoprotein metabolism in the metabolic syndrome is well complemented by extensive cell biological data. Nutritional modifications and increased physical exercise may favourably alter lipoprotein transport in the metabolic syndrome by collectively decreasing the hepatic secretion of VLDL-apoB and the catabolism of HDL apoA-I, as well as by increasing the clearance of LDL-apoB. Pharmacological treatments, such as statins, fibrates or fish oils, can also correct the dyslipidaemia by several mechanisms of action including decreased secretion and increased catabolism of apoB, as well as increased secretion and decreased catabolism of apoA-I. The complementary mechanisms of action of lifestyle and drug therapies support the use of combination regimens to treat dyslipidaemia in the metabolic syndrome.     

Prolonged interferon-gamma exposure decreases ion transport,NKCC1, and Na+-K+-ATPase expression in human intestinal xenografts in vivo

IFN-gamma is elevated in intestinal inflammation and alters barrier and transport functions in human colonic epithelial cell lines, but its effects on normal human small intestinal epithelium in vivo are poorly defined. We investigated effects of prolonged IFN-gamma exposure on ion transport and expression of transporters by using human fetal small intestinal xenografts. Xenograft-bearing mice were injected with IFN-gamma, and 24 h later xenografts were harvested and mounted in Ussing chambers. Baseline potential difference (PD) was not affected by IFN-gamma treatment. However, conductance was enhanced and agonist-stimulated ion transport was decreased. IFN-gamma also decreased expression of the Na+-K+-2Cl- cotransporter and the alpha-subunit of Na+-K+-ATPase compared with controls, whereas levels of the calcium-activated Cl- channel and CFTR were unaltered. Thus prolonged exposure to IFN-gamma leads to decreased ion secretion due, in part, to decreased ion transporter levels. These findings demonstrate the implications of elevated IFN-gamma levels in human small intestine and validate the human intestinal xenograft as a model to study chronic effects of physiologically relevant stimuli.     

The developmental origins of mammalian oocyte polarity

Drosophila has been an excellent model system to study the cell and molecular determinants of oocyte axis specification, a problem which is little known in mammalian species. Recent evidence supports the notion that mammalian oocytes utilize axis-orienting properties during the course of oogenesis. Among these, axis specification in relation to the oocyte cortex, germinal vesicle (GV) position, anchoring of GV and spindle, and patterning of follicle cell/oocyte attachments are proposed as conserved features of oogenesis in mammals that may be important to the survival and development of the preimplantation embryo.     

Structures of human MAP kinase kinase 1 (MEK1) and MEK2 describe novel noncompetitive kinase inhibition

MEK1 and MEK2 are closely related, dual-specificity tyrosine/threonine protein kinases found in the Ras/Raf/MEK/ERK mitogen-activated protein kinase (MAPK) signaling pathway. Approximately 30% of all human cancers have a constitutively activated MAPK pathway, and constitutive activation of MEK1 results in cellular transformation. Here we present the X-ray structures of human MEK1 and MEK2, each determined as a ternary complex with MgATP and an inhibitor to a resolution of 2.4 A and 3.2 A, respectively. The structures reveal that MEK1 and MEK2 each have a unique inhibitor-binding pocket adjacent to the MgATP-binding site. The presence of the potent inhibitor induces several conformational changes in the unphosphorylated MEK1 and MEK2 enzymes that lock them into a closed but catalytically inactive species. Thus, the structures reported here reveal a novel, noncompetitive mechanism for protein kinase inhibition.     

Evidence of glutathione transferase complexing and signaling in the model nematode Caenorhabditis elegans using a pull-down proteomic assay

Phage display techniques using random peptide interactions have supported the role of mammalian glutathione transferase (GST) as part of a signalling pathway for both oxidative stress and an apoptosis pathway. Little is known about the interaction of nonmammalian GST with other proteins. GSTs have been implicated in the development of chronic nematode infections by neutralising cytotoxic products arising from host immune initiated reactive oxygen species (ROS) assault. In this study we attached one of the key GSTs expressed in the model nematode Caenorhabditis elegans to an affinity support matrix and directly identified major interacting proteins by two-dimensional electrophoresis and peptide mass fingerprinting before and following oxidative stress. Nematode GST does not appear to be a stand-alone enzyme and interacts with many types of proteins in both normal and ROS stress conditions. Pull-down proteomic presents a flexible, label free, rapid and economical assay without specialised ligand fishing equipment to identify protein binding partners.     

Senescing human cells and ageing mice accumulate DNA lesions with unrepairable double-strand breaks

Humans and animals undergo ageing, and although their primary cells undergo cellular senescence in culture, the relationship between these two processes is unclear. Here we show that gamma-H2AX foci (gamma-foci), which reveal DNA double-strand breaks (DSBs), accumulate in senescing human cell cultures and in ageing mice. They colocalize with DSB repair factors, but not significantly with telomeres. These cryptogenic gamma-foci remain after repair of radiation-induced gamma-foci, suggesting that they may represent DNA lesions with unrepairable DSBs. Thus, we conclude that accumulation of unrepairable DSBs may have a causal role in mammalian ageing.     

Mistaken Identifiers: Gene name errors can be introduced inadvertently when using Excel in bioinformatics

Background  

When processing microarray data sets, we recently noticed that some gene names were being changed inadvertently to non-gene names.