The dynamics of experimental arable weed communities under different management practices

Abstract. Weed communities, comprising 12 introduced species at constant starting densities and three species already present in the seed bank, were followed through three years of continuous winter wheat. The wheat and weeds were subjected to two treatments in a split-plot factorial design, organic contrasting with conventional fertilizer, and ploughing plus hand-roguing contrasting with minimum tillage plus herbicide. The minimum tilled plots developed in a uniform manner, and became dominated by very high densities of Anisantha sterilis. Agrostemma githago and Galium aparine also persisted in these plots at lower densities. The ploughed plots had a lower total density but a greater range of species. Stellaria media, Veronica persica and Avena fatua were the most common; other species occurred at lower densities. The major effect of fertilizer treatment was a greater initial increase by G. aparine on the organic, minimum tilled plots compared with the conventionally fertilized, minimum tilled plots. Species associated with minimum tillage were annuals with either no or a short term seed bank and autumn germination and rather predictable dynamics, whereas species that did well under ploughing were either spring germinating or had a persistent seed bank, implying greater annual variation in population size associated with weather conditions. There seemed no clear way to distinguish between those species which were abundant on the ploughed plots and those which were scarce under all conditions using readily accessible data.     

Endogenous electric currents might guide rostral migration of neuroblasts

Mechanisms that guide directional migration of neuroblasts from the subventricular zone (SVZ) are not well understood. We report here that endogenous electric currents serve as a guidance cue for neuroblast migration. We identify the existence of naturally occurring electric currents (1.5±0.6 μA/cm², average field strength of ～3 mV/mm) along the rostral migration path in adult mouse brain. Electric fields of similar strength direct migration of neuroblasts from the SVZ in culture and in brain slices. The purinergic receptor P2Y1 mediates this migration. The results indicate that naturally occurring electric currents serve as a new guidance mechanism for rostral neuronal migration.     

Uncertainty associated with river health assessment in a varying environment: The case of a predictive fish-based index in France

Sensitive biological measures of river ecosystem quality are needed to assess, maintain or restore ecological conditions of water bodies. Since our understanding of these complex systems is imperfect, decision-making requires recognizing uncertainty. In this study, a new predictive multi-metric index based on fish functional traits was developed to assess French rivers. Information on fish assemblage structure, local environment and human-induced disturbances of 1654 French river sites was compiled. A Bayesian framework was used to predict theoretical metric values in absence of human pressure and to estimate the uncertainty associated with these predictions. The uncertainty associated with the index score gives the confidence associated with the evaluation of site ecological conditions.Among the 228 potential metrics tested, only 11 were retained for the index computation. The final index is independent from natural variability and sensitive to human-induced disturbances. In particular, it is affected by the accumulation of different degradations and specific degradations including hydrological perturbations. Predictive uncertainty is globally lower for IPR+ than for underlying metrics.This new methodology seems appropriate to develop bio-indication tools accounting for uncertainty related to reference condition definition and could be extended to other biological groups and areas. Our results support the use of multi-metric indexes to assess rivers and strengthen the idea that examination of uncertainty could contribute greatly to the improvement of the assessment power of bio-indicators.     

Some structural and functional properties of nerves and muscles in the oviduct of the pink bollworm moth,Pectinophora gossypiella (Saund.)

The oviduct of the pink bollworm is innervated by an intrinsic neural network arising from 4 nerves from the terminal ganglion. The nerve tracts in this network often contained elliptical swellings, each with a central nucleus.

A distinct surface topography was evident in the muscular sheath of the common and lateral oviduct. A very thin muscular envelope consisting of an inner band of circular fibers and an outer layer of longitudinal fibers was also found in the ovarioles. Although conventional A and I bands were recognized, the z-disk was composed of an irregular and loose meshwork, suggesting that the visceral muscles of the reproductive tract possess super-contracting properties. Even when the oviduct and the ovarioles were isolated from the central nervous system, an endogenous rhythmic activity was evident.

Two types of spontaneous excitatory postsynaptic potentials were detected in the oviduct. The type most frequently observed had a complex of multiple spikes with a duration of 18–32 msec. The other type had a saw-tooth shape and a duration of 80–160 msec. Spontaneous action potentials with a plateau-type configuration and a duration of 280–320 msec were also observed. After the removal of the terminal ganglion, endogenous electrical activity distinct from the events just described was found in the midand upper common oviduct. Such discharges seem to originate from the intrinsic neural network and had durations similar to those found for neurosecretory cells.     

Flamingo breeding: The role of group displays

Group displays in flamingos have been presumed to play a role in stimulating synchronous nesting and in facilitating pair formation. This study compares the group displays and breeding success of a captive flock of Caribbean flamingos (Phoenicopterus ruber ruber) at the National Zoological Park between 2 years: the frequency and synchrony of group displays were measured for a flock of 17 in 1988 and then again in 1989 after flock size was increased to 21. In 1989 the rate of occurrence of display activity increased 48%, the synchrony of group displays increased 100%, the frequency of mounts and copulations almost doubled, and for the first time in the flock's history two fertile eggs were produced. The use of sprinklers to simulate rain had no effect on the group displays. The amount of naturally occurring rainfall in 1989 was almost twice that in 1988. The increased frequency and synchrony of group displays could be attributed to increased flock size, change in sex ratio, addition of strange individuals, or increased rainfall. This study, however, provides evidence for a relationship between behavioral stimulation from group displays and components of breeding success in flamingos.     

Fertility preservation and preimplantation genetic assessment for women with breast cancer

Breast cancer is the most common cancer diagnosed among reproductive aged women, and its treatment can compromise future fertility. Options for fertility preservation include oocyte or embryo cryopreservation after ovarian stimulation (OS), which are the most established choices and are applicable for adult women with cancer. Ovarian tissue freezing may also be appropriate, as it offers potentially the least delay. The recognisation of the role of BRCA1 and BRCA2 mutations in some women has led to the involvement of preimplantation genetic diagnosis (PGD), recently renamed preimplantation genetic testing for monogenic disorder (PGT-M), whereby embryos are created by IVF and cell(s) are removed and genetically analyzed for specific disease-related mutations. PGT-M offers a valid option for women wishing to avoid transmission of the predisposition for hereditary breast cancer to their offspring. The aim of this paper is to provide an overview of the factors that influence fertility preservation in newly diagnosed breast cancer patients, and to illustrate the option of PGT-M to enable conception of an unaffected child.     

Evolución clínica y funcional de los pacientes que ingresan en residencias tras una fractura de cadera. Implementación de un programa de intervención multinivel

Background and objectiveThe aim of this study was to determine the clinical and functional outcomes of patients discharged to nursing homes after a hip fracture.MethodsThe study included all patients admitted to a group of nursing homes after a hip fracture in 2016. A geriatric assessment protocol was applied, and patients were treated with a specific protocol for 90 days. They were assessed for nutritional status (Mini-Nutritional Assessment and Body Mass Index), pain (Visual Analogue Scale, and the PAINAD Scale), the presence of pressure ulcers, blood test (D vitamin, haemoglobin, proteins), and functional status (Barthel index and Functional Assessment Categories).ResultsOut of a total of 175 patients, 116 (75%) met the inclusion criteria. The mean age was 84.9 years old (±6.7 SD), and 91 (78.4%) were women. At admission, 73.8% of 65 residents had anaemia, 76.7% hypovitaminosis D, 88% malnutrition or «at risk of malnutrition», and 15.3% had pressure ulcers. After 90 days, the moderate-severe functional status (Barthel index < 60) was reduced from 90.4 to 39.6%, dependence due to gait from 97.3 to 36.1%, and moderate-severe pain from 88.9 to 14.4%. Most of the pressure ulcers healed (94.4%).ConclusionsPatients admitted to nursing homes after a hip fracture had poor clinical and functional status. This study shows that after 90 days from admission these patients had positive outcomes in terms of functionality, gait, pain control, and pressure ulcers healing.     

Ammonite aptychi: Functions and role in propulsion

Seven previous proposals of aptychus (sensu stricto) function are reviewed: lower mandible, protection of gonads of females, protective operculum, ballasting, flushing benthic prey, filtering microfauna and pump for jet propulsion. An eighth is introduced: aptychi functioned to actively stabilize the rocking produced by the pulsating jet during forward foraging and backward swimming. Experiments with in-air models suggest that planispiral ammonites could lower their aperture by the forward shift of a mobile cephalic complex. In the experiments, the ventral part of the peristome is lowered from the lateral resting (neutral) position by the added “ballast” of a relatively thin Laevaptychus to an angle < 25° from horizontal with adequate stability to withstand the counter-force produced by the jet of the recurved hyponome. However, of the shell forms tested, only brevidomes with thick aptychi, e.g., the Upper Jurassic Aspidoceratidae with Laevaptychus and average whorl expansion rates, were stable enough to swim forward by jet propulsion at about Nautilus speed (∼ 25 cm/s). We propose that aptychus function most commonly combined feeding (jaw, flushing, filtering) with protection (operculum), and, more rarely, with locomotion (ballast, pump, diving and stabilizing plane). Aptychi may thus have been multi-functional.