Electromyography and the evolution of motor control: limitations and insights

Electromyography (EMG), or the study of muscle activation patterns,has long been used to infer central nervous system (CNS) controlof the musculoskeletal system and the evolution of that control.As the activation of the muscles at the level of the peripheryis a reflection of the interaction of descending influencesand local reflex control, EMG is an important tool in integratedinvestigations of the evolution of coordination in complex,musculoskeletal systems. Yet, the use of EMG as a tool to understandthe evolution of motor control has its limitations. We herereview the potential limitations and opportunities of the useof EMG in studying the evolution of motor control in vertebratesand provide original previously unpublished data to illustratethis. The relative timing of activation of a set of musclescan be used to evaluate CNS coordination of the components ina musculoskeletal system. Studies of relative timing revealtask-dependent variability in the recruitment of different populationsof muscle fibers (i.e., different fiber types) within a singlemuscle, and left–right asymmetries in activation thatneed to be taken into account in comparative studies. The magnitudeof muscle recruitment is strongly influenced by the instantaneousdemands imposed on the system, and is likely determined by localreflex-control systems. Consequently, using EMG to make meaningfulinferences about evolutionary changes in musculoskeletal controlrequires comparisons across similar functional tasks. Moreover,our data show that inferences about the evolution of motor controlare limited in their explanatory power without proper insightsinto the kinematics and dynamics of a system.     

Simple inhibitors of histone deacetylase activity that combine features of short-chain fatty acid and hydroxamic acid inhibitors

Butyric acid and trichostatin A (TSA) are anti-cancer compounds that cause the upregulation of genes involved in differentiation and cell cycle regulation by inhibiting histone deacetylase (HDAC) activity. In this study we have synthesized and evaluated compounds that combine the bioavailability of short-chain fatty acids, like butyric acid, with the bidentate binding ability of TSA. A series of analogs were made to examine the effects of chain length, simple aromatic cap groups, and substituted hydroxamates on the compounds' ability to inhibit rat-liver HDAC using a fluorometric assay. In keeping with previous structure-activity relationships, the most effective inhibitors consisted of longer chains and hydroxamic acid groups. It was found that 5-phenylvaleric hydroxamic acid and 4-benzoylbutyric hydroxamic acid were the most potent inhibitors with IC50's of 5 microM and 133 microM respectively.     

The immunobiology of mushrooms

There has been enormous interest in the biologic activity of mushrooms and innumerable claims have been made that mushrooms have beneficial effects on immune function with subsequent implications for inhibition of tumor growth. The majority of these observations are anecdotal and often lack standardization. However, there remains considerable data on both in vitro and in vivo effects that reflect on the potential of mushroom compounds to influence human immunity. A number of these effects are beneficial but, unfortunately, many responses are still characterized based on phenomenology and there is more speculation than substance. With respect to tumor biology, although many neoplastic lesions are immunogenic, tumor antigens frequently are self antigens and induce tolerance and many patients with cancer exhibit suppressed immune responses, including defective antigen presentation. Therefore, if and when mushroom extracts are effective, they more likely function as a result of improved antigen presentation by dendritic cells than by a direct cytopathic effect. In this review we attempt to place these data in perspective, with a particular focus on dendritic cell populations and the ability of mushroom extracts to modulate immunity. There is, at present, no scientific basis for the use of either mushrooms or mushroom extracts in the treatment of human patients but there is significant potential for rigorous research to understand the potential of mushrooms in human disease and thence to focus on appropriate clinical trials to demonstrate effectiveness and/ or potential toxicity.     

Directional evolution of stockiness coevolves with ecology and locomotion in lizards

Although studied in many taxa, directional macroevolution remains difficult to detect and quantify. We present an approach for detecting directional evolution in subclades of species when relatively few species are sampled, and apply it to studying the evolution of stockiness in Phrynosomatine lizards. Our approach is more sensitive to detecting the tempo of directional evolution than other available approaches. We use ancestral reconstruction and phylogenetic mapping of morphology to characterize the direction and magnitude of trait evolution. We demonstrate a directional trend toward stockiness in horned lizards, but not their sister groups, finding that stockier species tend to have relatively short and wide bodies, and relatively short heads, tails, and limbs. Ornstein–Uhlenbeck models show that the directional trend in horned lizards is due to a shift in selective regime and stabilizing selection as opposed to directional selection. Bayesian evolutionary correlation analyses indicate that stockier species run more slowly and eat a larger proportion of ants. Furthermore, species with larger horns tend to be slower and more ant-specialized. Directional evolution toward a stocky body shape has evolved in conjunction with changes in a suite of traits, representing a complex example of directional macroevolution.     

Sperm mitochondrial integrity is not required for hyperactivated motility, zona binding, or acrosome reaction in the rhesus macaque

Whether the main energy source for sperm motility is from oxidative phosphorylation or glycolysis has been long-debated in the field of reproductive biology. Using the rhesus monkey as a model, we examined the role of glycolysis and oxidative phosphorylation in sperm function by using alpha-chlorohydrin (ACH), a glycolysis inhibitor, and pentachlorophenol (PCP), an oxidative phosphorylation uncoupler. Sperm treated with ACH showed no change in percentage of motile sperm, although sperm motion was impaired. The ACH-treated sperm did not display either hyperactivity- or hyperactivation-associated changes in protein tyrosine phosphorylation. When treated with PCP, sperm motion parameters were affected by the highest level of PCP (200 microM); however, PCP did not cause motility impairments even after chemical activation. Sperm treated with PCP were able to display hyperactivity and tyrosine phosphorylation after chemical activation. In contrast with motility measurements, treatment with either the glycolytic inhibitor or the oxidative phosphorylation inhibitor did not affect sperm-zona binding and zona-induced acrosome reaction. The results suggest glycolysis is essential to support sperm motility, hyperactivity, and protein tyrosine phosphorylation, while energy from oxidative phosphorylation is not necessary for hyperactivated sperm motility, tyrosine phosphorylation, sperm-zona binding, and acrosome reaction in the rhesus macaque.     

Nonomuraea candida sp. nov., a new species from South African soil

A novel actinomycete, strain HMC10^T, was isolated from a soil sample taken from the banks of the Gamka River in the Swartberg Nature Reserve, Western Cape Province, South Africa. Strain HMC10^T was identified as a member of the genus Nonomuraea by a polyphasic approach. Strain HMC10^T could be differentiated from other members of the genus Nonomuraea on the basis of physiology and 16S rRNA gene sequence analysis. DNA-DNA hybridization further differentiated strain HMC10^T from its nearest phylogenetic neighbour, Nonomuraea turkmeniaca NRRL B-16246^T (4.5 ± 3.8% DNA relatedness). Strain HMC10^T exhibited weak antibiosis against Mycobacterium aurum A+, but none against Mycobacterium tuberculosis H37Rv^T. The name Nonomuraea candida is proposed, with the type strain HMC10^T (= DSM 45086^T = NRRL B-24552^T). The GenBank accession number for the 16S rRNA gene sequence of Nonomuraea candida HMC10^T is DQ285421.