Higher-level snake phylogeny inferred from mitochondrial DNA sequences of 12S rRNA and 16S rRNA genes

Portions of two mitochondrial genes (12S and 16S ribosomal RNA) were sequenced to determine the phylogenetic relationships among the major clades of snakes. Thirty-six species, representing nearly all extant families, were examined and compared with sequences of a tuatara and three families of lizards. Snakes were found to constitute a monophyletic group (confidence probability [CP] = 96%), with the scolecophidians (blind snakes) as the most basal lineages (CP = 99%). This finding supports the hypothesis that snakes underwent a subterranean period early in their evolution. Caenophidians (advanced snakes), excluding Acrochordus, were found to be monophyletic (CP = 99%). Among the caenophidians, viperids were monophyletic (CP = 98%) and formed the sister group to the elapids plus colubrids (CP = 94%). Within the viperids, two monophyletic groups were identified: true vipers (CP = 98%) and pit vipers plus Azemiops (CP = 99%). The elapids plus Atractaspis formed a monophyletic clade (CP = 99%). Within the paraphyletic Colubridae, the largely Holarctic Colubrinae was found to be a monophyletic assemblage (CP = 98%), and the Xenodontinae was found to be polyphyletic (CP = 91%). Monophyly of the henophidians (primitive snakes) was neither supported nor rejected because of the weak resolution of relationships among those taxa, except for the clustering of Calabaria with a uropeltid, Rhinophis (CP = 94%).      

Inhibition of human skin fibroblast collagenase, thermolysin, and Pseudomonas aeruginosa elastase by peptide hydroxamic acids.

The hydroxamic acid HONHCOCH2CH(i-Bu)CO-L-Trp-NHMe, isomer 6A (GM 6001), inhibits human skin fibroblast collagenase with Ki of 0.4 nM using the synthetic thiol ester substrate Ac-Pro-Leu-Gly-SCH(i-Bu)CO-Leu-Gly-OEt at pH 6.5. The other isomer, 6B, which has the opposite configuration at the CH2CH(i-Bu)CO alpha-carbon atom, has a Ki of 200 nM for this enzyme. GM 6001 is one of the most potent inhibitors of human skin fibroblast collagenase yet reported. GM 6001 has a Ki of 20 nM against thermolysin and Pseudomonas aeruginosa elastase. Isomer 6B has a Ki of 7 nM against thermolysin and 2 nM against the elastase. 6A and 6B are the most potent hydroxamate inhibitors reported for these bacterial enzymes. The pattern of inhibition for all three enzymes suggests that isomer 6A is the (R,S) compound, stereochemically analogous to the L,L-dipeptide, and isomer 6B is the (S,S) compound, analogous to the DL-dipeptide. The tolerance of the D configuration by thermolysin and the elastase allows these inhibitors to discriminate between the human and bacterial enzymes simply by inversion of configuration at the CH2CH(i-Bu)CO alpha-carbon atom. Substitution of the potential metal liganding groups carboxylate and hydrazide for the hydroxamate group yields much weaker inhibitors for all three enzymes.     

Salivary alpha amylase and salivary cortisol response to fluid consumption in exercising athletes

The objective of the study was to examine salivary biomarker response to fluid consumption in exercising athletes. Exercise induces stress on the body and salivary alpha amylase (sAA) and salivary cortisol are useful biomarkers for activity in the sympathoadrenal medullary system and the hypothalamic pituitary adrenal axis which are involved in the stress response. Fifteen college students were given 150 ml and 500 ml of water on different days and blinded to fluid condition. The exercise protocol was identical for both fluid conditions using absolute exercise intensities ranging from moderate to high. Saliva was collected prior to exercise, post moderate and post high intensities and analyzed by Salimetrics assays. Exercise was significant for sAA with values different between pre-exercise (85 ± 10 U · ml⁻¹) and high intensity (284 ± 30 U · ml⁻¹) as well as between moderate intensity (204 ± 32 U · ml⁻¹) and high intensity. There was no difference in sAA values between fluid conditions at either intensity. Exercise intensity and fluid condition were each significant for cortisol. Cortisol values were different between pre-exercise (0.30 ± 0.03 ug · dL⁻¹) and high intensity (0.45 ± 0.05 ug · dL⁻¹) as well as between moderate intensity (0.33 ± 0.04 ug · dL⁻¹) and high intensity. Moderate exercise intensity cortisol was lower in the 500 ml condition (0.33 ± 0.03 ug · dL⁻¹) compared with the 150 ml condition (0.38 ± 0.03 ug · dL⁻¹). This altered physiological response due to fluid consumption could influence sport performance and should be considered. In addition, future sport and exercise studies should control for fluid consumption.     

Pregnancy success of lactating Holstein cows after a single administration of a sustained-release formulation of recombinant bovine somatotropin

Background

Results regarding the use of bovine somatotropin for enhancing fertility in dairy cattle are variable. Here, the hypothesis was tested that a single injection of a sustained-release preparation of bovine somatotropin (bST) during the preovulatory period would improve pregnancy success of lactating dairy cows at first service.

Results

The first experiment was conducted in a temperate region of Mexico. Cows inseminated following natural estrus or timed artificial insemination were given a single injection of bST or a placebo injection at insemination (n = 100 cows per group). There was no significant difference between bST and control groups in the proportion of inseminated cows diagnosed pregnant (29 vs 31% pregnant). The second experiment was performed during heat stress in Florida. Cows were subjected to an ovulation synchronization regimen for first insemination. Cows treated with bST received a single injection at 3 days before insemination. Controls received no additional treatment. As expected, bST did not increase vaginal temperature. Treatment with bST did not significantly increase the proportion of inseminated cows diagnosed pregnant although it was numerically greater for the bST group (24.2% vs 17.8%, 124–132 cows per group). There was a tendency (p = 0.10) for a smaller percent of control cows to have high plasma progesterone concentrations (≥ 1 ng/ml) at Day 7 after insemination than for bST-treated cows (72.6 vs 81.1%). When only cows that were successfully synchronized were considered, the magnitude of the absolute difference in the percentage of inseminated cows that were diagnosed pregnant between bST and control cows was reduced (24.8 vs 22.4% pregnant for bST and control).

Conclusion

Results failed to indicate a beneficial effect of bST treatment on fertility of lactating dairy cows.

     

The relationship between the L1 and L2 domains of the insulin and epidermal growth factor receptors and leucine-rich repeat modules

Background  

Leucine-rich repeats are one of the more common modules found in proteins. The leucine-rich repeat consensus motif is LxxLxLxxNxLxxLxxLxxLxx- where the first 11–12 residues are highly conserved and the remainder of the repeat can vary in size Leucine-rich repeat proteins have been subdivided into seven subfamilies, none of which include members of the epidermal growth factor receptor or insulin receptor families despite the similarity between the 3D structure of the L domains of the type I insulin-like growth factor receptor and some leucine-rich repeat proteins.     

Reduction of liver macrophage transduction by pseudotyping lentiviral vectors with a fusion envelope from Autographa californica GP64 and Sendai virus F2 domain

Background  

Lentiviral vectors are well suited for gene therapy because they can mediate long-term expression in both dividing and nondividing cells. However, lentiviral vectors seem less suitable for liver gene therapy because systemically administered lentiviral vectors are preferentially sequestered by liver macrophages. This results in a reduction of available virus and might also increase the immune response to the vector and vector products.     

Inhibition of collagenase from Clostridium histolyticum by phosphoric and phosphonic amides

Di- and tripeptides with sequences present in collagen that are known to occupy the S1' through S3' subsites at the active site of the collagenase from Clostridium histolyticum do not themselves inhibit this zinc protease. Thus glycylproline, glycylprolylalanine, and their C-terminal amides are not inhibitors. N alpha-Phosphorylglycylproline, N alpha-phosphorylglycyl-L-prolyl-L-alanine, and their C-terminal amides are weak inhibitors with IC50's (concentration causing half-maximal inhibition) of 4.6, 0.8, 3, and 1.5 mM, respectively. Extension of glycyl-L-prolyl-L-alanine to L-leucyl-glycyl-L-prolyl-L-alanine gives a tetrapeptide known to occupy the S1, S1', S2', and S3' subsites of collagenase when present in collagen but that still does not itself inhibit the enzyme. (Isoamylphosphonyl)glycyl-L-prolyl-L-alanine, a peptide containing a tetrahedral phosphorus atom at the position of the amide carbonyl carbon of the L-leucylglycyl amide bond of the parent tetrapeptide, inhibits collagenase with an IC50 of 16 microM, at least 1000-fold more potent than the parent peptide. Substitution of the two-carbon ethyl chain of alanine for the five-carbon isoamyl chain of leucine increases the IC50 to 46 microM. Substitution of the n-decyl chain for the isoamyl chain does not change the IC50. (Isoamylphosphonyl)glycyl-glycyl-L-proline contains a tripeptide that does not occupy the S1' through S3' subsites of collagenase when this peptide is present in collagen and thus has an IC50 of 4.4 mM. (Isoamylphosphonyl)glycyl-L-prolyl-L-alanine may be an analogue of the tetrahedral transition state for the hydrolysis of the natural collagen substrate.(ABSTRACT TRUNCATED AT 250 WORDS)