A model for quantitative strength training of hindlimb muscles of the rat

Rats were taught to lift up a lever to train the plantar flexors. After 2 wk of adaptation the rats were trained for 36 wk. The mass of weights on the lever rose by 85% over the 36-wk period (P less than 0.05) The estimated force that the plantar flexors had to develop to lift the lever rose by 32% (P less than 0.05), just as the work per lift rose by 28% (P less than 0.05). For the trained group of rats the soleus muscles of the right and the left limb were 34% (P less than 0.05) and 31% (P less than 0.05) heavier, respectively, after the training period than those of the control group. Similarly, the plantaris muscles of both the right and the left limb were 24% heavier (P less than 0.05). For the trained group the maximum twitch and tetanus tensions of the soleus were 63% (P less than 0.05) and 65% (P less than 0.05) higher, respectively. Relative to the plantaris these measures were 79% (P less than 0.05) and 37% (P less than 0.05), respectively. The described model, therefore, seems appropriate for the study of the skeletal muscles' adaptation to usage.     

Contractile properties of old rat muscles: effect of increased use

To examine how different kinds of activity affect the composition and contractile properties of aging skeletal muscle, old male rats were strength and swim trained. The mass of weights lifted during the strength training increased by 85 +/- 9% (P less than 0.05), which was accompanied by an increase by 32 +/- 5% (P less than 0.05) of the estimated force developed. The wet muscle weight of the soleus and the plantaris decreased significantly with age. The phenomenon was counteracted but not neutralized by the strength training. Twitch and tetanic tension also decreased significantly with age in both the soleus and plantaris muscle. This was avoided by the strength training. This training also significantly decreased time to peak tension and half-relaxation time of both muscles. The swim training increased the heart-to-body weight ratio by 21 +/- 5% (P less than 0.05) and the endurance of the soleus muscle. Time to peak tension and triosephosphate dehydrogenase activity of the plantaris muscle were strongly correlated (P less than 0.001) with myosin adenosinetriphosphatase activity. The results show that the composition and contractile properties of old skeletal muscle are considerably affected by strength training repeated during a substantial period of old age, whereas swim training only affects the endurance of the skeletal muscle.     

Recombination among multiple mitochondrial pseudogenes from a Passerine genus

PCR products of a fragment of the mitchondrial protein coding subunit 5 of NADH-dehydrogenase (ND5) from eight individuals representing five species of the South American bird genus Conirostrum were cloned. The 130 clones, which were subsequently sequenced, constituted 55 different sequences. Due to the observed differences in substitution patterns 58% of the cloned sequences were identified as pseudogenes. Recombination could be traced in 19% of the inferred nuclear pseudogenes, but this figure probably represents a significant underestimation of the factual recombination events. The nonrecombined pseudogenes consisted of multiple haplotypes found to diverge from 1 to 16% from the mitochondrial gene. The number of mitochondrial nuclear copies and their apparent frequent recombination suggest that pseudogenes constitute a serious potential risk in confounding phylogenetic studies and population genetic analysis.     

Putative in vitro expressed gene fragments unique to Mycobacterium avium subspecies paratuberculosis

By a suppression subtractive hybridization based method, nine novel Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) fragments of between 318 and 596 bp have been identified and characterized. Database search revealed little or no similarity with other mycobacteria. The uniqueness and diagnostic potential of seven of these fragments in relation to M. paratuberculosis closest relative Mycobacterium avium subsp. avium (M. avium) was confirmed by species-specific PCR and Southern blot. Furthermore, RT-PCR indicated that eight of the nine fragments originate from areas of the genome that are expressed in vitro.     

Identification of thermostable β-xylosidase activities produced by <Emphasis Type="Italic">Aspergillus brasiliensis</Emphasis> and <Emphasis Type="Italic">Aspergillus niger</Emphasis>

Twenty Aspergillus strains were evaluated for production of extracellular cellulolytic and xylanolytic activities. Aspergillus brasiliensis, A. niger and A. japonicus produced the highest xylanase activities with the A. brasiliensis and A. niger strains producing thermostable β-xylosidases. The β-xylosidase activities of the A. brasiliensis and A. niger strains had similar temperature and pH optima at 75°C and pH 5 and retained 62% and 99%, respectively, of these activities over 1 h at 60°C. At 75°C, these values were 38 and 44%, respectively. Whereas A. niger is a well known enzyme producer, this is the first report of xylanase and thermostable β-xylosidase production from the newly identified, non-ochratoxin-producing species A. brasiliensis.     

The use of phylogeny to interpret cross-cultural patterns in plant use and guide medicinal plant discovery: an example from Pterocarpus (Leguminosae)

Background

The study of traditional knowledge of medicinal plants has led to discoveries that have helped combat diseases and improve healthcare. However, the development of quantitative measures that can assist our quest for new medicinal plants has not greatly advanced in recent years. Phylogenetic tools have entered many scientific fields in the last two decades to provide explanatory power, but have been overlooked in ethnomedicinal studies. Several studies show that medicinal properties are not randomly distributed in plant phylogenies, suggesting that phylogeny shapes ethnobotanical use. Nevertheless, empirical studies that explicitly combine ethnobotanical and phylogenetic information are scarce.

Methodology/Principal Findings

In this study, we borrowed tools from community ecology phylogenetics to quantify significance of phylogenetic signal in medicinal properties in plants and identify nodes on phylogenies with high bioscreening potential. To do this, we produced an ethnomedicinal review from extensive literature research and a multi-locus phylogenetic hypothesis for the pantropical genus Pterocarpus (Leguminosae: Papilionoideae). We demonstrate that species used to treat a certain conditions, such as malaria, are significantly phylogenetically clumped and we highlight nodes in the phylogeny that are significantly overabundant in species used to treat certain conditions. These cross-cultural patterns in ethnomedicinal usage in Pterocarpus are interpreted in the light of phylogenetic relationships.

Conclusions/Significance

This study provides techniques that enable the application of phylogenies in bioscreening, but also sheds light on the processes that shape cross-cultural ethnomedicinal patterns. This community phylogenetic approach demonstrates that similar ethnobotanical uses can arise in parallel in different areas where related plants are available. With a vast amount of ethnomedicinal and phylogenetic information available, we predict that this field, after further refinement of the techniques, will expand into similar research areas, such as pest management or the search for bioactive plant-based compounds.     

The unique pollen morphology of Duparquetia (Leguminosae: Caesalpinioideae): developmental evidence of aperture orientation using confocal microscopy

BACKGROUND AND AIMS: The phylogenetic affinities of the aberrant monotypic genus Duparquetia (subfamily Caesalpinioideae) are at present unresolved. Preliminary results from molecular analyses suggest a basal, isolated position among legumes. A study of Duparquetia pollen was carried out to provide further morphological characters to contribute to multi-data set analyses. Understanding the development of Duparquetia pollen was necessary to clarify the orientation of the apertures. METHODS: Pollen grains and developing microspores were examined using light microscopy, confocal microscopy and scanning electron microscopy. Evidence for the orientation of the apertures was provided by the examination of microspores within developing tetrads, using (a) confocal microscopy to locate the position of the ectoapertures, and (b) light microscopy and Alcian blue stain to locate the position of the endoapertures. KEY RESULTS: Confocal microscopy has been used for the first time to examine developing microspores in order to obtain information on ectoapertures that was unavailable using other techniques. Pollen in Duparquetia develops in tetrahedral tetrads as in other eudicots, with the apertures arranged in a modified pattern following Fischer's rule. Pollen grains are asymmetrical and have one equatorial-encircling ectoaperture with two equatorial endoapertures, a unique feature in Leguminosae, and in eudicots. CONCLUSIONS: The pollen morphology of Duparquetia is so unusual that it provides little information to help determine its closest relatives. However, it does fit with a pattern of greater pollen morphological diversity in the first-branching caesalpinioid legume groups than in the more derived clades. The latitudinal ectoaperture of Duparquetia is unique within the Fabales and eudicot clades, resembling more closely the monosulcate pollen found in monocots and basal angiosperms; however, developmental patterns are recognizably similar to those of all other legume pollen types.     

Expressional changes in cerebrovascular receptors after experimental transient forebrain ischemia

Background

Global ischemic stroke is one of the most prominent consequences of cardiac arrest, since the diminished blood flow to the brain results in cell damage and sometimes permanently impaired neurological function. The post-arrest period is often characterised by cerebral hypoperfusion due to subacute hemodynamic disturbances, the pathophysiology of which are poorly understood. In two other types of stroke, focal ischemic stroke and subarachnoid hemorrhage, it has earlier been demonstrated that the expression of certain vasoconstrictor receptors is increased in cerebral arteries several days after the insult, a phenomenon that leads to increased contraction of cerebral arteries, reduced perfusion of the affected area and worsened ischemic damage. Based on these findings, the aim of the present study was to investigate if transient global cerebral ischemia is associated with upregulation of vasoconstrictive endothelin and 5-hydroxytryptamine receptors in cerebral arteries. Experimental transient forebrain ischemia of varying durations was induced in male wistar rats, followed by reperfusion for 48 hours. Neurological function was assessed daily by three different tests and cerebrovascular expression and contractile function of endothelin and 5-hydroxytryptamine receptors were evaluated by wire myography, immunohistochemistry and western blotting.

Results

Transient forebrain ischemia induced neurological deficits as well as functional upregulation of vasoconstrictive ET_B and 5-HT_1B receptors in cerebral arteries supplying mid- and forebrain regions. No receptor upregulation was seen in arteries supplying the hindbrain. Immunohistochemical stainings and western blotting demonstrated expressional upregulation of these receptor subtypes in the mid- and forebrain arteries and confirmed that the receptors were located in the smooth muscle layer of the cerebral arteries.

Conclusions

This study reveals a new pathophysiological aspect of global ischemic stroke, namely expressional upregulation of vasoconstrictor receptors in cerebral arteries two days after the insult, which might contribute to cerebral hypoperfusion and delayed neuronal damage after cardiac arrest.