A functional model for maximum growth of immature stone loach, Barbatula barbatula, from three populations in north-west England

1. The chief objective was to develop a functional model for growth of stone loach, Barbatula barbatula, using immature fish from three populations. The growth model had been developed previously for brown trout, Salmo trutta, but new estimates of the five parameters for the stone loach had to be obtained from laboratory experiments. 2. Fish from four size groups (initial arithmetic mean live weights 0.053 g, 0.231 g, 0.840 g, 1.612 g, with five fish per group) from Great Oaks Wood Beck were acclimatized to constant temperatures of either 3, 5, 10, 15, 20 or 25 °C. Each fish was kept in a separate tank and fed to satiation on freshwater shrimps. Weights and lengths of each fish were recorded at the start and finish of a growth period of 35 days. For each of the other populations (Black and Ford Wood Becks), there were only three temperatures (5, 10, 20 °C) with ten fish per temperature. 3. The growth model was an excellent fit (P < 0.001, R² > 0.99) for the 120 fish from Great Oaks Wood Beck. Growth rates were negative at 3 °C, close to zero at 5 and 25 °C, and positive at 10, 15 and 20 °C, with an optimum value of 19 °C. When growth rates were positive, they decreased markedly with increasing fish weight for small fish but decreased more slowly for larger fish. At the start of the experiments, weight–length relationships were similar for fish from all three populations and were well described by a power function. There was excellent agreement between growth rates estimated from the fitted growth model for fish from Great Oaks Wood Beck and values obtained for fish from Black and Ford Wood Becks. Data from all three populations were therefore pooled (n = 180) to obtain new estimates of the five parameters in the model. 4. Comparisons between parameter estimates for trout and stone loach showed that the latter grew better in warmer waters (e.g. optimum value for growth was 19.0 °C for stone loach and 13.1 °C for trout, with ranges for growth of 5.0–25.0 °C and 3.6–19.5 °C, respectively).     

Density‐dependent prophylaxis in primary anti‐parasite barriers in the velvetbean caterpillar

1. Organisms rely on a set of primary barriers to prevent invasion by parasites, and secondary defences to fight parasites that breach the primary barriers. However, maintaining these defences to be active and effective is costly. Thus, hosts increase investment in anti‐parasite defences under situations of high risk of infection and reduce defences when the risk is reduced (the ‘Density‐Dependent Prophylaxis’ hypothesis). 2. In the present study, it was tested whether the midgut primary defences of the velvetbean caterpillar Anticarsia gemmatalis Hübner present density‐dependent plasticity, and also whether these defences could be induced by a viral pathogenic challenge. The aim was to examine whether morphometry and the structure of the midgut and peritrophic matrix (PM) change in accordance with colour transition in caterpillars, and whether such changes may provide the caterpillars a more protective barrier against invasion by Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV). 3. It was found that PM and the midgut epithelium of the velvetbean caterpillar change plastically according to phenotype, itself a response to changes in population density. Caterpillars reared at high densities (black phenotype) had a considerably thicker midgut epithelia and peritrophic matrices than those reared individually (green phenotype), and there was also more chitin in the PM of the former. 4. This was interpreted as the first demonstration of increased investment in primary, barrier, defences against parasites, in response to increased conspecific density and an increased risk of infection. The possibility that this arises as a positive result of pleiotropy is discussed further, wherein the biochemical pathways responsible for the up‐regulation of the immune system are also involved in midgut properties.     

Human mesenchymal stromal cells do not promote recurrence of soft tissue sarcomas in mouse xenografts after radiation and surgery

Background. Mesenchymal stromal cells (MSCs) promote wound healing, including after radiotherapy (RT) and surgery. The use of MSCs in regenerative medicine in the context of malignancy, such as to enhance wound healing post-RT/surgery in patients with soft tissue sarcomas (STSs), requires safety validation. The aim of this study was to determine the effects of human MSCs on STS growth in vitro and local recurrence and metastasis in vivo. Methods. Human primary STS and HT-1080 fibrosarcoma lines were transduced to express luciferase/eGFP (enhanced green fluorescent protein). Sarcoma cells were co-cultured or co-injected with bone marrow–derived MSCs for growth studies. Xenograft tumor models were established with STS lines in NOD/SCID/γ_c^null mice. To emulate a clinical scenario, subcutaneous tumors were treated with RT/surgery prior to MSC injection into the tumor bed. Local and distant tumor recurrence was studied using histology and bioluminescence imaging. Results. MSCs did not promote STS proliferation upon co-culture in vitro, which was consistent among MSCs from different donors. Co-injection of MSCs with sarcoma cells in mice exhibited no significant tumor-stimulating effect, compared with control mice injected with sarcoma cells alone. MSC administration after RT/surgery had no effect on local recurrence or metastasis of STS. Discussion. These studies are important for the establishment of a safety profile for MSC administration in patients with STS. Our data suggest that MSCs are safe in STS management after standard of care RT/surgery, which can be further investigated in early-phase clinical trials to also determine the efficacy of MSCs in reducing morbidity and to mitigate wound complications in these patients.     

The challenges of conservation for declining migrants: are reserve‐based initiatives during the breeding season appropriate for the Pied Flycatcher Ficedula hypoleuca?

Creating conservation policies for declining migrant species in response to global change presents a considerable challenge. Migrant species are affected by factors at breeding grounds, overwintering areas and during migration. Accordingly, reserve-based management during the breeding season is not always a suitable conservation strategy. Recent Pied Flycatcher population decline typifies the pattern for many migrants. The UK population has declined by 43% in the past decade, but explanations, and possible solutions, remain elusive. We use 15 years of data (1990–2004) from a declining British population to establish possible reasons for decline, considering: (1) breeding performance (including the influences of competition and predation); (2) weather patterns caused by the winter phase (December–March) of the North Atlantic Oscillation (NAO), which modify conditions experienced at wintering grounds and on migration; and (3) possible impacts of climate change on spring temperatures. We conclude that decreasing breeding performance is contributing to decline, but that non-breeding factors are more important. Winter NAO index is a strong predictor of breeding population, probably because it influences food abundance in Africa and at migratory stopover points. Importantly, however, year itself enhances the predictive model, indicating that influences on population remain unaccounted for by current research. Management strategies based on increasing breeding productivity cannot fully address population decline because non-breeding factors appear important. However, as breeding performance is declining, breeding-based strategies remain useful conservation tools. To this end, our research indicates that optimal placement of nestboxes as regards orientation and habitat management to increase larval food supplies could increase productivity significantly.     

Development and Validation of a Wing Key to Improve Harvest Management of Alcids in the Northwest Atlantic

Abstract: Murres (thick-billed [Uria lomvia] and common [U. aalge]) are legally hunted along the coast of Newfoundland and Labrador, Canada. Razorbills (Alca torda) are also incidentally taken. Only irregular estimates of the total murre harvest are available, so a tool to derive estimates of age- and species-specific harvest is required to effectively monitor the hunt and manage a sustainable harvest. We collected 293 murre and razorbill wings from hunters between 1999–2004, with the goal of identifying wing characteristics that could be used to discriminate age and species. We found that murres and razorbills could be reliably aged (first-yr vs. older) on the basis of molt limits of greater wing coverts. Using a discriminant function (DF) incorporating length of the first primary and second secondary feather, we classified 95–96% of common murres and 99–100% of thick-billed murres correctly to species. First-year thick-billed and common murres also differed in number of pale secondary coverts (median = 12 and 3, respectively), providing another species-specific trait. We developed a key to age and assign species based on these results. We assessed applicability and accuracy of the wing-key with novice observers, who differentiated between murre and razorbill wings using feather-pattern coloration with high accuracy (95 ± 9%) and were able to differentiate between the 2 murres species using 3 techniques: visual assessment of wing shape (83 ± 14% accuracy), the DF (94 ± 6%), and number of worn secondary coverts for first-year birds only (83 ± 5%). Experience increased success rates of aging and species classification using wing shape and number of worn secondary coverts but not using the DF. Despite differences in measurement accuracy and repeatability among observers, the DF proved to be robust. Our results will facilitate implementation of a species composition survey for the murre hunt and will improve identification rates of carcasses found during beached bird surveys in the Northwest Atlantic, aiding in monitoring of alcid populations vulnerable to anthropogenic activities.     

Divergent patterns of diversification in courtship and genitalic characters of Timema walking‐sticks

Understanding the patterns of diversification in sexual traits and the selection underlying such diversification represents a major unresolved question in evolutionary biology. We examined the phylogenetic diversification for courtship and external genitalic characters across ten species of Timema walking‐sticks, to infer the tempos and modes of character change in these sexual traits and to draw inferences regarding the selective pressures underlying speciation and diversification in this clade. Rates of inferred change in male courtship behaviours were proportional to speciation events, but male external genitalic structures showed a pattern of continuous change across evolutionary time, with divergence proportional to branch lengths. These findings suggest that diversification of courtship behaviour is mediated by processes that occur in association with speciation, whereas diversification of genitalia occurs more or less continuously, most likely driven by forces of sexual selection.     

Observations on the Cytology of Halidrys siliquosa (L.) Lyngb.

A study of the cytology of Halidrys siliquosa suggests thatit has a haploid thallus with reduction division immediatelyfollowing fertilization. There appear to be eight chromosomesin vegetative cells and developing antheridial and oogonialcells. Typical ‘bouquet’ and diakinesis stages suggestinga reduction division have been seen on germination of the zygote.