Nerve function restoration following targeted muscle reinnervation after varying delayed periods

Targeted muscle reinnervation has been proposed for reconstruction of neuromuscular function in amputees.However,it is unknown whether performing delayed targeted muscle reinnervation after nerve injury will affect restoration of function.In this rat nerve injury study,the median and musculocutaneous nerves of the forelimb were transected.The proximal median nerve stump was sutured to the distal musculocutaneous nerve stump immediately and 2 and 4 weeks after surgery to reinnervate the biceps brachii.After targeted muscle reinnervation,intramuscular myoelectric signals from the biceps brachii were recorded.Signal amplitude gradually increased with time.Biceps brachii myoelectric signals and muscle fiber morphology and grooming behavior did not significantly differ among rats subjected to delayed target muscle innervation for different periods.Targeted muscle reinnervation delayed for 4 weeks can acquire the same nerve function restoration effect as that of immediate reinnervation.

Agent-based models reveal limits of mark-release-recapture estimates for the rare butterfly, Bhutanitis thaidina (Lepidoptera: Papilionidae)

Insect diversity and abundance are in drastic decline worldwide,but quantifying insect populations to better conserve them is a difficult task.Mark-release-recapture(MRR)is widely used as an ecological indicator for insect populations,but the accuracy of MRR estimates can vary with factors such as spatial scale,sampling effort and models of inference.We conducted a 3-year MRR study of B.thaidina in Yanzigou valley,Mt.Gongga but failed to obtain sufficient data for a robust population estimate.This prompted us to integrate B.thaidina life history information to parameterize agent-based models and evaluate the conditions under which successful MRR studies could be conducted.We evaluated:(1)the performance of MRR models under different landscape types,and(2)the influence of experimental design on the accuracy and variance of MRR-based estimates.Our simulations revealed systematic underestimates of true population parameters by MRR models when sampling effort was insufficient.In a total of 2772 simulations,subjective decisions in sampling protocol(e.g.,frequency,number of sampling locations,use of spatially explicit models,type of estimands)accounted for nearly half of the variation in estimates.We conclude that MRR-based estimates could be improved with the addition of more field-specific parameters.

Stochastic processes play more important roles in driving the dynamics of rarer species

Aims One major goal of modern community ecology is to understand how deterministic and stochastic processes combine to drive community assembly.However,little empirical knowledge is known about how their relative importance varies between common and rare species.Methods We exploited two 30-year data sets of plant communities in a temperate steppe using two different methods.One is a null model method,and the other is a recently developed direct-calculation method.Important Findings We found that stochastic processes tended to be more important in influencing rare than common species.This finding suggests that stochastic forces may play a more important role in structuring communities with more rare species,providing a possible solution to the debate on the varied importance of deterministic and stochastic processes among different communities.

The shift in the abundance of two Stipa species in response to land use change is associated with their divergent reproductive strategies

Aims The divergent changes of plant species under land use changes are key mechanisms underlying vegetation succession.Stipa grandis steppe and Stipa krylovii steppe are two plant commu-nities widely distributed on the Mongolian Plateau.They have been speculated to be able to succeed into each other under different land use types and intensities based on the observa-tions on their presence and abundance at the sites with dif-ferent land use history.However,no direct evidence,neither the underlying mechanisms,have been reported for this specu-lation.Here,we verified this speculation and explored the underlying mechanisms in the typical steppe region of Inner Mongolia.Methods We investigated the abundance and reproductive behavior of S.kry-lovii and S.grandis under different land use types and intensities.We used 18 grassland paddocks to run a 6-year experiment with 6 management treatments(T0-unused,T1-grazing monthly in plant growing season,T2,T4,T6-grazing in different months in plant growing season,and T8-mowing)replicated three times.We measured the relative density and cover of S.krylovii and S.grandis using line sampling method and examined their number and bio-mass of vegetative and reproductive tillers using quadrat method in each paddock after treatments for 4 and 6 years.We also de-termined these plant attributes in 14 pairs of heavily versus lightly used grassland plots in a wide area(150 km×200 km)of the typical steppe region.Important Findings 1.Grazing largely and mowing moderately decreased the density ratio and coverage ratio of S.grandis to S.krylovii in grasslands(P<0.05),and the differences in these ratios between grazed and unused grasslands increased with time.2.Grazing,but not mowing,significantly enhanced the relative density(N_(rep)=reproductive tiller number/total tiller number)of,and biomass allocation(B_(rep)=reproductive tiller biomass/total bio-mass)to,reproductive tillers of S.krylovii(P<0.05),but not S.gran-dis.This grazing enhancement to sexual reproduction of S.krylovii,and additionally inhibition to N_(rep) of S.grandis(P<0.05),were found across the 14 pairs of heavily versus lightly used plots.3.Seasonal pattern of grazing affected sexual reproduction of S.kry-lovii.The N_(rep) and B_(rep) was higher under grazing in July and September(T4)than in July and August(T6)or in May and July(T2)(P<0.05),suggesting a relatively positive effect of grazing on sexual reproduction in July(tasseling phenophase)than in May or August.Our results provide direct evidence to the reciprocal change of S.grandis and S.krylovii in steppe communities under different management and indicate that gazing or mowing enhancement of sexual reproduction of S.krylovii relative to S.grandis is one of the mechanisms for the change.