Age-related changes in neuromuscular function of the quadriceps muscle in physically active adults

Substantial evidence exists for the age-related decline in maximal strength and strength development. Despite the importance of knee extensor strength for physical function and mobility in the elderly, studies focusing on the underlying neuromuscular mechanisms of the quadriceps muscle weakness are limited.The aim of this study was to investigate the contributions of age-related neural and muscular changes in the quadriceps muscle to decreases in isometric maximal voluntary torque (iMVT) and explosive voluntary strength. The interpolated twitch technique and normalized surface electromyography (EMG) signal during iMVT were analyzed to assess changes in neural drive to the muscles of 15 young and 15 elderly volunteers. The maximal rate of torque development as well as rate of torque development, impulse and neuromuscular activation in the early phase of contraction were determined. Spinal excitability was estimated using the H reflex technique. Changes at the muscle level were evaluated by analyzing the contractile properties and lean mass.The age-related decrease in iMVT was accompanied by a decline in voluntary activation and normalized surface EMG amplitude. Mechanical parameters of explosive voluntary strength were reduced while the corresponding muscle activation remained primarily unchanged. The spinal excitability of the vastus medialis was not different while M wave latency was longer. Contractile properties and lean mass were reduced.In conclusion, the age-related decline in iMVT of the quadriceps muscle might be due to a reduced neural drive and changes in skeletal muscle properties. The decrease in explosive voluntary strength seemed to be more affected by muscular than by neural changes.     

Moths in fragments: insights into the biology and ecology of the Australian endangered golden sun moth Synemon plana (Lepidoptera: Castniidae) in natural temperate and exotic grassland remnants

The conservation and management of endangered species requires an adequate understanding of their biology and ecology. Although there has been an increasing appreciation in Australia of the need for greater efforts to conserve insects, there is only limited information available that can be used to underpin conservation efforts. The endangered golden sun moth, Synemon plana (Lepidoptera: Castniidae) is a flagship species endemic to natural temperate grassland in south-eastern Australia. Most populations of this species are at considerable risk from habitat loss, weed invasion and inadequate management. Despite the considerable knowledge that exists about the species biology and ecology, efforts to improve the species conservation status are hampered because there are still critical gaps in our understanding of the species’ natural history. In particular, the ecology of the larvae is not known. Our study examined the abundance, population structure and reproductive biology of the moths in a broad sample of both natural temperate and exotic grassland remnants in and near Canberra in the Australian Capital Territory (ACT) in south-eastern Australia. The results fill critical gaps in the knowledge needed to achieve effective conservation management. From our findings, it is clear that the species inhabits grasslands dominated by a mixture of native wallaby grasses (Rytidosperma spp. (formerly Austrodanthonia)) and spear grasses (Austrostipa spp.). In contrast to earlier suggestions that S. plana is entirely confined to natural temperate grassland, mature and immature life stages of the species were also present in grasslands comprised entirely of the exotic Chilean needlegrass (Nassella neesiana). Most of the S. plana populations surveyed in the ACT were characterised by low relative abundance with only very few large populations being recorded. The conservation of exotic grasslands as substitute habitat for S. plana is discussed and suggestions regarding future monitoring and research of the species are provided.     

Abnormal etioplast development in barley seedlings infected with BSMV by seed transmission

The effect of barley stripe mosaic hordeivirus (BSMV) was studied on the ultrastructure of etioplasts, protochlorophyllide forms and the greening process of barley ( Hordeum vulgare cv. Pannónia) plants infected by seed transmission. The leaves of 7- to 11-day-old etiolated seedlings were examined by transmission electron microscopy, fluorescence and absorption spectroscopy. The etioplasts of infected seedlings contained smaller prolamellar bodies with less regular membrane structure, while prothylakoid content was higher than in the control. The protochlorophyllide content of virus-infected seedlings was reduced to 74% of the control. In the 77 K fluorescence spectra the relative amount of 655 nm emitting photoactive protochlorophyllide form decreased, and the amount of the 645 and 633 nm emitting forms increased in the infected leaves. A characteristic effect was observed in the process of the Shibata-shift: 40 min delay was observed in the infected leaves. The results of this work proved that BSMV infection delays or inhibits plastid development and the formation of photosynthetic apparatus.     

Functional expression, purification, and characterization of the recombinant Baeyer-Villiger monooxygenase MekA from Pseudomonas veronii MEK700

For the investigation of the NADPH-dependent Baeyer-Villiger monooxygenase MekA from Pseudomonas veronii MEK700, the encoding gene mekA with a C-terminal strep-tag was cloned and expressed under the control of a l-rhamnose inducible promoter from Escherichia coli. The mekA gene was found by analyzing the methylethylketone (MEK) degradation pathway by Onaca et al. J Bacteriol 189:3759–3767, 2007. Sequence analysis of the corresponding protein, which catalyzes the Baeyer-Villiger oxidation of MEK to ethyl acetate, showed two binding sites (Rossman-fold motifs) for cofactors NAD(P)H and FAD. Although expression of mekA resulted in large amounts of inclusion bodies compared to soluble protein, high amounts of purified and active MekA were obtained by affinity chromatography. The substrate spectrum of MekA was investigated with purified enzyme and whole cells using a variety of aliphatic, aromatic, and cyclic ketones including four chiral substrates. The specific activity of MekA with MEK as substrate was determined to be 1.1 U/mg protein. K _M values were determined for MEK and the cofactors NADPH and NADH to be 6, 11, and 29 μM, respectively.     

Directed evolution of a Baeyer–Villiger monooxygenase to enhance enantioselectivity

The Baeyer-Villiger monooxygenase (BVMO) BmoF1 from Pseudomonas fluorescens DSM 50106 was shown before to enantioselectively oxidize different 4-hydroxy-2-ketones to the corresponding hydroxyalkyl acetates, being the first example of a BVMO-catalyzed kinetic resolution of aliphatic acyclic ketones. However, the wild-type enzyme exhibited only moderate E values (E approximately 55). Thus, the enantioselectivity was enhanced by means of directed evolution and optimization of reaction conditions since it was found that higher E values (E approximately 70 for wild-type BmoF1) could already be obtained when performing biotransformations in shake flasks rather than small tubes. In a first step, random mutations were introduced by error-prone polymerase chain reaction, and BmoF1 mutants (>3,500 clones) were screened for improved activity and enantioselectivity using a microtiter-plate-based screening method. Mutations S136L and L252Q were found to increase conversion compared to wild type, while several mutations (H51L, F225Y, S305C, and E308V) were identified enhancing the enantioselectivity to a varying extent (E approximately 75-90). In a second step, beneficial mutations were recombined by consecutive cycles of QuikChange site-directed mutagenesis resulting in a double mutant (H51L/S136L) showing both improved conversion and enantioselectivity (E approximately 86).     

Workers dominate male production in the neotropical bumblebee Bombus wilmattae (Hymenoptera: Apidae)

Background

Cooperation and conflict in social insects are closely linked to the genetic structure of the colony. Kin selection theory predicts conflict over the production of males between the workers and the queen and between the workers themselves, depending on intra-colonial relatedness but also on other factors like colony efficiency, sex ratios, cost of worker reproduction and worker dominance behaviour. In most bumblebee (Bombus) species the queen wins this conflict and often dominates male production. However, most studies in bumblebees have been conducted with only a few selected, mostly single mated species from temperate climate regions. Here we study the genetic colony composition of the facultative polyandrous neotropical bumblebee Bombus wilmattae, to assess the outcome of the queen-worker conflict over male production and to detect potential worker policing.

Results

A total of 120 males from five colonies were genotyped with up to nine microsatellite markers to infer their parentage. Four of the five colonies were queen right at point of time of male sampling, while one had an uncertain queen status. The workers clearly dominated production of males with an average of 84.9% +/- 14.3% of males being worker sons. In the two doubly mated colonies 62.5% and 96.7% of the male offspring originated from workers and both patrilines participated in male production. Inferring the mother genotypes from the male offspring, between four to eight workers participated in the production of males.

Conclusions

In this study we show that the workers clearly win the queen-worker conflict over male production in B. wilmattae, which sets them apart from the temperate bumblebee species studied so far. Workers clearly dominated male production in the singly as well the doubly mated colonies, with up to eight workers producing male offspring in a single colony. Moreover no monopolization of reproduction by single workers occurred.     

Citizen science and wildlife biology: Synergies and challenges

Citizen science (CS) has evolved over the past decades as a working method involving interested citizens in scientific research, for example by reporting observations, taking measurements or analysing data. In the past, research on animal behaviour has been benefitting from contributions of citizen scientists mainly in the field of ornithology but the full potential of CS in ecological and behavioural sciences is surely still untapped. Here, we present case studies that successfully applied CS to research projects in wildlife biology and discuss potentials and challenges experienced. Our case studies cover a broad range of opportunities: large‐scale CS projects with interactive online tools on bird song dialects, engagement of stakeholders as citizen scientists to reduce human–wildlife conflicts, involvement of students of primary and secondary schools in CS projects as well as collaboration with the media leading to successful recruitment of citizen scientists. Each case study provides a short overview of the scientific questions and how they were approached to showcase the potentials and challenges of CS in wildlife biology. Based on the experience of the case studies, we highlight how CS may support research in wildlife biology and emphasise the value of fostering communication in CS to improve recruitment of participants and to facilitate learning and mutual trust among different groups of interest (e.g., researchers, stakeholders, students). We further show how specific training for the participants may be needed to obtain reliable data. We consider CS as a suitable tool to enhance research in wildlife biology through the application of open science procedures (i.e., open access to articles and the data on publicly available repositories) to support transparency and sharing experiences.