Impact of methodological factors on sperm penetration into cervical mucus in cattle

The aim of this study was to investigate the influence of methodological factors on the interaction of bovine spermatozoa and homologous cervical mucus. Cervical mucus was obtained from three cows during estrus. To evaluate the penetration ability of frozen-thawed semen samples of five different bulls, fresh mucus as well as frozen-thawed mucus, stored for 1, 10 or 30 d in liquid nitrogen, were used. Penetration assays were performed at 38 degrees C for 10 min, and the most advanced spermatozoon was located and the distance determined. Semen parameters were examined by a computer-assisted videomicrographic system. Conservation of mucus in liquid nitrogen for up to 30 d did not influence the results of the penetration assay. In contrast, the mucus of individual cows showed significant differences in the migration distance of spermatozoa. Sperm concentration, mean velocity and number of forward moving spermatozoa were significantly correlated with mucus penetration. These results demonstrated that the mucus penetration assay in cattle can be performed by dividing a mucus sample from a cow into many portions and storing the sample in liquid nitrogen.     

Deafferentation of the urinary bladder and implantation of a sacral anterior root stimulator (SARS) for treatment of the neurogenic bladder in paraplegic patients.

Since 25 years electrical stimulation has become an established and widely acknowledged therapy option. Today, FES is widely employed, e.g. for cardiostimulation, diaphragm stimulation, kinetotherapy, for treatment of tremor in Parkinson patients, and finally for bladder stimulation in patients with bladder voiding dysfunctions. Brindley was the first researcher who succeeded in stimulating the spinal nerves via implanted electrodes in an animal model. In the years 1978/79 Brindley implanted five paraplegic patients with so-called sacral anterior root stimulators; all of them were able to void under stimulation. This method of sacral anterior root stimulation (SARS) proved an alternative to frequent one-way catheterisation for patients with severe voiding dysfunctions, without achieving complete continence, however. The following study is to provide an overview over the latest insights in the context of implanting sacral anterior root stimulators; it discusses the preconditions required for such interventions and presents criteria to decide in which cases there is a contraindication for sacral deafferentation of the posterior roots. Moreover, it contrasts advantages and disadvantages of the intradural and extradural implantation methods and presents the currently available long-term follow-up results with SDAF and SARS for treatment of bladder voiding dysfunctions.     

An aspartate deletion mutation defines a binding site of the multifunctional FhuA outer membrane receptor of Escherichia coli K-12.

The FhuA protein of the outer membrane serves as a receptor for phages T5, T1, and phi 80, for colicin M, for the antibiotic albomycin, and for ferrichrome and related siderophores. To identify protein regions important for the multiple FhuA activities, fhuA genes of spontaneous chromosomal mutants which expressed wild-type amounts of the FhuA protein were sequenced. A mutant which was partially T5 sensitive but impaired in all other functions was missing aspartate residue 348 of the mature protein as a result of a three-base deletion. This aspartate residue is part of the hydrophilic sequence Asp-Asp-Glu-Lys. Replacement by site-specific mutagenesis of each of the Asp residues by Tyr, of Glu by Val, and of Lys by Met reduced FhuA activity but less than the Asp deletion did. Ferrichrome inhibited binding of phage phi 80 and of colicin M to these mutants in an allele-specific manner. A completely resistant derivative of the Asp deletion mutant contained, in addition, a leucine-to-proline substitution at position 106 and eight changed bases, converting at positions 576 to 578 an Arg-Pro-Leu sequence to Ala-Arg-Cys. The latter mutations and the Leu-to-Pro replacement alone did not alter sensitivity to the phages but reduced sensitivity to colicin M and albomycin 10- to 1,000-fold. The proline replacements probably disturb FhuA conformation and, in concert with the Asp deletion, inactivate FhuA completely. It is concluded that the Asp deletion site defines a region of FhuA which directly participates in binding of all FhuA ligands. Growth promotion studies on iron-limited media revealed that certain siderophores of the hydroxamate type, such as butylferrichrome, ferrichrysin, and ferrirubin, are taken up not only via FhuA but also via the FhuE outer membrane receptor protein.     

Combining Evolutionary Information and an Iterative Sampling Strategy for Accurate Protein Structure Prediction

Recent work has shown that the accuracy of ab initio structure prediction can be significantly improved by integrating evolutionary information in form of intra-protein residue-residue contacts. Following this seminal result, much effort is put into the improvement of contact predictions. However, there is also a substantial need to develop structure prediction protocols tailored to the type of restraints gained by contact predictions. Here, we present a structure prediction protocol that combines evolutionary information with the resolution-adapted structural recombination approach of Rosetta, called RASREC. Compared to the classic Rosetta ab initio protocol, RASREC achieves improved sampling, better convergence and higher robustness against incorrect distance restraints, making it the ideal sampling strategy for the stated problem. To demonstrate the accuracy of our protocol, we tested the approach on a diverse set of 28 globular proteins. Our method is able to converge for 26 out of the 28 targets and improves the average TM-score of the entire benchmark set from 0.55 to 0.72 when compared to the top ranked models obtained by the EVFold web server using identical contact predictions. Using a smaller benchmark, we furthermore show that the prediction accuracy of our method is only slightly reduced when the contact prediction accuracy is comparatively low. This observation is of special interest for protein sequences that only have a limited number of homologs.     

Structure Learning in Bayesian Sensorimotor Integration

Previous studies have shown that sensorimotor processing can often be described by Bayesian learning, in particular the integration of prior and feedback information depending on its degree of reliability. Here we test the hypothesis that the integration process itself can be tuned to the statistical structure of the environment. We exposed human participants to a reaching task in a three-dimensional virtual reality environment where we could displace the visual feedback of their hand position in a two dimensional plane. When introducing statistical structure between the two dimensions of the displacement, we found that over the course of several days participants adapted their feedback integration process in order to exploit this structure for performance improvement. In control experiments we found that this adaptation process critically depended on performance feedback and could not be induced by verbal instructions. Our results suggest that structural learning is an important meta-learning component of Bayesian sensorimotor integration.     

Extracting Objective Estimates of Sedentary Behavior from Accelerometer Data: Measurement Considerations for Surveillance and Research Applications

BackgroundAccelerometer-based activity monitors are widely used in research and surveillance applications for quantifying sedentary behavior (SB) and physical activity (PA). Considerable research has been done to refine methods for assessing PA, but relatively little attention has been given to operationalizing SB parameters (i.e., sedentary time and breaks) from accelerometer data - particularly in relation to health outcomes. This study investigated: (a) the accrued patterns of sedentary time and breaks; and (b) the associations of sedentary time and breaks in different bout durations with cardiovascular risk factors.MethodsAccelerometer data on 5,917 adults from the National Health Examination and Nutrition Survey (NHANES) 2003–2006 were used. Sedentary time and breaks at different bout durations (i.e., 1, 2–4, 5–9, 10–14, 15–19, 20–24, 25–29, and ≥30-min) were obtained using a threshold of <100 counts per minute. Sedentary time and breaks were regressed on cardiovascular risk factors (waist circumference, triglyceride, and high-density lipoprotein cholesterol) and body mass index across bout durations.ResultsThe results revealed that the majority of sedentary time occurred within relatively short bout durations (≈70% and ≈85% for <5-min and <10-min, respectively). The associations of sedentary time and breaks with health outcomes varied depending on how bout time was defined. Estimates of SB parameters based on bout durations of 5 min or shorter were associated with reduced cardiovascular risk factors while durations longer than 10-min were generally associated with increased risk factors.ConclusionsThe present study demonstrates that the duration of sedentary bouts should be further considered when operationalizing the SB parameters from accelerometer data. The threshold of 5 minutes to define a bout is defensible, but a 10 minute threshold would provide a more conservative estimate to clearly capture the prolonged nature of sedentary behavior. Additional research is needed to determine the relative sensitivity and specificity of these thresholds.     

Absence of pollinators and apomictic fruit production in an Atlantic rainforest population of Cymbopetalum brasiliense (Annonaceae)

Breeding system and pollination biology of an isolated population of Cymbopetalum brasiliense (Annonaceae), a large-flowered understory tree, was studied during two consecutive flowering seasons in October/November 2007 and September/October 2008. Flowers were morphologically comparable to other Cymbopetalum species and generally to other Annonaceae taxa adapted to pollination by large beetles, such as Annona spp. Flowers were thermogenic and emitted a strong scent during the pistillate and staminate flowering phases. Heating of the floral chamber was most intense during the pistillate phase between 1800 and 1900?h (up to 6°C difference to air temperature). Floral scent consisted almost entirely of p-methylanisole. None of the 133 flowers examined during two seasons received any visitation by dynastid beetles or other potential pollinators. Lycaenid larvae (Oenomaus ortygnus) attacked buds and flowers in both flowering seasons and destroyed about 20% of all buds in the 2007 season. Fruit set was high (72% of nonpredated flowers in 2007), despite the absence of pollinators. Field experiments showed that agamospermic reproduction rather than self-pollination was most likely responsible for fruit production. The study reports a probable case of apomixis, which would be the first in the Annonaceae family.     

Permutation tests for random effects in linear mixed models

Inference regarding the inclusion or exclusion of random effects in linear mixed models is challenging because the variance components are located on the boundary of their parameter space under the usual null hypothesis. As a result, the asymptotic null distribution of the Wald, score, and likelihood ratio tests will not have the typical χ(2) distribution. Although it has been proved that the correct asymptotic distribution is a mixture of χ(2) distributions, the appropriate mixture distribution is rather cumbersome and nonintuitive when the null and alternative hypotheses differ by more than one random effect. As alternatives, we present two permutation tests, one that is based on the best linear unbiased predictors and one that is based on the restricted likelihood ratio test statistic. Both methods involve weighted residuals, with the weights determined by the among- and within-subject variance components. The null permutation distributions of our statistics are computed by permuting the residuals both within and among subjects and are valid both asymptotically and in small samples. We examine the size and power of our tests via simulation under a variety of settings and apply our test to a published data set of chronic myelogenous leukemia patients.