Molecular evolution of mitochondrial 12S RNA and cytochrome b sequences in the pantherine lineage of Felidae

DNA sequence comparisons of two mitochondrial DNA genes were used to infer phylogenetic relationships among 17 Felidae species, notably 15 in the previously described pantherine lineage. The polymerase chain reaction (PCR) was used to generate sequences of 358 base pairs of the mitochondrial 12S RNA gene and 289 base pairs of the cytochrome b protein coding gene. DNA sequences were compared within and between 17 felid and five nonfelid carnivore species. Evolutionary trees were constructed using phenetic, cladistic, and maximum likelihood algorithms. The combined results suggested several phylogenetic relationships including (1) the recognition of a recently evolved monophyletic genus Panthera consisting of Panthera leo, P. pardus, P. onca, P. uncia, P. tigris, and Neofelis nebulosa; (2) the recent common ancestry of Acinonyx jubatus, the African cheetah, and Puma concolor, the American puma; and (3) two golden cat species, Profelis temmincki and Profelis aurata, are not sister species, and the latter is strongly associated with Caracal caracal. These data add to the growing database of vertebrate mtDNA sequences and, given the relatively recent divergence among the felids represented here (1-10 Myr), allow 12S and cytochrome b sequence evolution to be addressed over a time scale different from those addressed in most work on vertebrate mtDNA.      

A small intraexonic deletion within the dystrophin gene suggests a possible mechanism of mutagenesis

A case of Duchenne muscular dystrophy is described with an unusual mutation consisting of a 17-bp deletion within exon 47 of the dystrophin gene. The sequences on either side of the deletion have a high degree of intrastrand base complementarity. It is hypothesised that the mechanism generating the deletion may have been the formation of a hairpin loop structure in a single strand of DNA followed by enzymatic degradation at unpaired regions within the loop. Received: 4 January 1997 / Revised: 21 January 1997     

Effects of tibialis anterior vibration on postural control when exposed to support surface translations

The sensory re-weighting theory suggests unreliable inputs may be down-weighted to favor more reliable sensory information and thus maintain proper postural control. This study investigated the effects of tibialis anterior (TA) vibration on center of pressure (COP) motion in healthy individuals exposed to support surface translations to further explore the concept of sensory re-weighting. Twenty healthy young adults stood with eyes closed and arms across their chest while exposed to randomized blocks of five trials. Each trial lasted 8?s, with TA vibration either on or off. After 2?s, a sudden backward or forward translation occurred. Anterior–posterior (A/P) COP data were evaluated during the preparatory (first 2?s), perturbation (next 3?s), and recovery (last 3?s) phases to assess the effect of vibration on perturbation response features. The knowledge of an impending perturbation resulted in reduced anterior COP motion with TA vibration in the preparatory phase relative to the magnitude of anterior motion typically observed during TA vibration. During the perturbation phase, vibration did not influence COP motion. However, during the recovery phase vibration induced greater anterior COP motion than during trials without vibration. The fact that TA vibration produced differing effects on COP motion depending upon the phase of the perturbation response may suggest that the immediate context during which postural control is being regulated affects A/P COP responses to TA vibration. This indicates that proprioceptive information is likely continuously re-weighted according to the context in order to maintain effective postural control.     

Chemical shift assignments for the Ig2 domain of human obscurin A

The giant sarcomeric protein obscurin (~720 kDa) is an essential contributor to myofibrillogenesis and acts as the only known tether between the contractile apparatus and the surrounding membrane structures in myofibrils. Genomic characterization of OBSCN suggests a modular architecture, consisting of dozens of individually-folded Ig-like and FnIII-like domains arranged in tandem. Here we describe the sequence-specific chemical shift assignments of the second putative obscurin Ig-like domain (Ig2). This domain specifically binds to MyBP-C slow variant-1 through an unknown mechanism. Ultimately, the assignments presented here will facilitate high-resolution structure determination of Ig2 and provide insight into the specificity of the obscurin-MyBP-C interaction.     

Evidence from immunoblotting studies on uncoupling protein that brown adipose tissue is not present in the domestic pig

Adipose tissues and other tissues of the pig have been examined for the presence of the mitochondrial "uncoupling protein," characteristic of brown adipose tissue, in order to assess whether brown fat is present in this species. Mitochondria were prepared from various tissues and the proteins separated on the basis of molecular weight by sodium dodecyl sulphate--polyacrylamide gel electrophoresis. Immunoblotting procedures were then used to probe for uncoupling protein, employing a rabbit anti-(rat uncoupling protein) serum. Pigs were examined at 4 days, 4 weeks, and 8 weeks of age. No evidence for the presence of uncoupling protein was found at any of these ages. The protein was, however, readily detected in brown adipose tissue from rats, mice, golden hamsters, guinea pigs, Richardson's ground squirrel, and lambs. An additional group of pigs was acclimated to the cold (10 degrees C) for a period of 10 days prior to the examination of tissues, but again uncoupling protein was not detected in any tissue. These results indicate that uncoupling protein is either absent from adipose tissues of the pig or is present at such a low concentration that it is unlikely to support thermogenesis. It is concluded that the pig does not contain adipose tissue that is functionally "brown;" adipose tissues in this species appear to be exclusively "white."     

Cloning and partial DNA sequencing of two new human papillomavirus types associated with condylomas and low-grade cervical neoplasia.

Using low-stringency Southern blot analysis and cloning in lambda bacteriophage, two new human papillomavirus types (HPV-43 and HPV-44) were identified and their DNAs were cloned from vulvar tissues. The isolates were characterized by restriction endonuclease mapping and shown to be new HPV types on the basis of their minimal hybridization with all other known HPV types at high stringency. Both HPVs are most closely related to types 6, 11, and 13. HPV-43 did not exhibit any cross-reactivity with these HPV types at high stringency. HPV-44 showed minimal cross-reactivity to HPV-13, which was in the range of 20 to 25% according to liquid hybridization analysis. The deduced genomic organization of each of the two new HPVs was colinear with HPV-6b. Prevalence studies revealed that HPV-43 and HPV-44 together were found in 6 of 439 normal cervical tissues, in 8 of 195 cervical intraepithelial neoplasms, but in none of 56 cervical cancers tested thus far.     

Réseaux de grains cytoplasmiques dans les cellules de l'organe de Bidder chez Bufo bufo L.

Résumé Les cellules de l'organe de Bidder, observées à l'aide du microscope électronique, contiennent dans leur cytoplasme des structures granulaires qui sont inconnues dans les ovocytes des ovaires d'Amphibiens. Ces structures sont formées de grains disposés concentriquement autour de vésicules allongées du réticulum lisse. Les grains, chacun de 140 Å, sont reliés entre eux par des fibrilles dans des plans circulaires et superposés, formant ainsi des réseaux cylindriques ou fusiformes. Ces réseaux peuvent être rassemblés et orientés pour constituer des faisceaux. Ils peuvent perdre le reticulum qui axe leur structure et fusionner, tandis que les grains s'associent étroitement et prennent l'aspect de fibres. Ils peuvent aussi être associés avec un matériel dense et amorphe, qui ressemble au ciment intermitochondrial. L'hypothèse d'une organisation de ribosomes est discutée.

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Granular networks in the cells of Bidder's organ in Bufo bufo L.

Summary The cells of the Bidder's organ, observed with the electron microscope, reveal in their cytoplasm granular structures unknown in Amphibian oocytes. These structures are formed of granules concentrically organized around lengthened vesicles of smooth reticulum. The granules, each about 140 Å, are linked to each other by fibrils in circular and superposed planes constituting cylindrical or spindle-shaped networks. These networks may be rassembled and directed in a way to constitute fasciculi. They may lose the reticulum which support their structure and blend into one another, while the granules closely associate each other and take the appearance of fibers. They may be connected with a dense and amorph material, which looks like intermitochondrial cement. The hypothesis about an organisation of ribosomes is discussed.

     

Induction and characterization of -galactosidase in an extreme thermophile

A thermostable beta-galactosidase (EC 3.2.1.23; beta-dgalactoside galactohydrolase) was found to be inducible in an extreme thermophile resembling Thermus aquaticus. Enzyme induction was achieved by the addition of lactose, galactose, or the alpha-galactoside, melibiose, to growing cultures. The addition of glucose to induced cultures had a repressive effect on further enzyme synthesis. The enzyme was purified 78-fold, and the optimum temperature and pH for activity were determined to be 80 C and pH 5.0, respectively. The enzyme was activated by both manganese and ferrous iron. Sulfhydryl activation and thermal stabilization indicate that the thermophilic beta-galactosidase is a sulfhydryl enzyme. Kinetic determinations at 80 C established a K(m) of 2.0 x 10(-3)m for the chromogenic substrate o-nitrophenyl beta-d-galactopyranoside (ONPG) and a K(1) of 7.5 x 10(-3)m for lactose. The Arrhenius energy of activation (for the hydrolysis of ONPG) was calculated to be 13.7 kcal/mole. A molecular weight of 5.7 x 10(5) daltons was estimated by elution of the enzyme from Sephadex 4B.     

Effects of Tebuthiuron on aquatic productivity

Tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N-dimethylurea) appears to control the riparian shrub saltcedar (Tamarix spp.); however, its use is restricted since the fate and effects of this herbicide in aquatic systems are unknown. Possible tebuthiuron impacts on aquatic production were examined in ten 2846-1 three-phase, open-system mesocosms. Each mesocosm contained sediment, water, algae, micro- and macroinvertebrates and fish, and was open to the atmosphere for gas exchange and colonization by indigenous macroinvertebrates and algae. The following nominal doses of tebuthiuron were used: 0 (control), 10, 70, 200, 500, and 1000 g 1^–1. The 200 g 1^–1 dose approximated the highest concentration of tebuthiuron detected in a water body after experimental application to a watershed. Data generated from all treatment levels were used in tebuthiuron fate analysis and in correlation analysis between the mesocosm variables. The control and the 200 g 1^–1 treatment level were replicated (n = 3) to allow for additional statistical analyses of treatment effects at the 200 g 1^–1 level. The adsorption of tebuthiuron to sediments contained in ten mesocosms was described by the Freundlich equation, x/m = 3.24c^0.68. Phytoplankton primary production, chironomid density, and chironomid biomass were negatively correlated with tebuthiuron concentration during peak system productivity. Conversely, no trends were observed at any sample date between an omnivorous fish species and herbicide concentration. At the 200 g 1^–1 dose level, only chironomid density was reduced. Factors responsible for reductions in chironomid density may include 1) a species shift in the 200 g 1^–1 treatment algal assemblages toward a greater percentage of unpalatable biomass, and 2) decreased algal productivity and/or an algal species shift in mesocosms receiving dose levels greater than 200 g 1^–1. Chironomid density reduction at the 200 g 1^–1 dose level suggests that deleterious effects may occur in some stream systems exposed to a 200 g 1^–1 tebuthiuron concentration.Contribution No. T-9-367 of the College of Agricultural Sciences, Texas Tech University.Contribution No. T-9-367 of the College of Agricultural Sciences, Texas Tech University.