A circumpolar study unveils a positive non-linear effect of temperature on arctic arthropod availability that may reduce the risk of warming-induced trophic mismatch for breeding shorebirds.

Seasonally abundant arthropods are a crucial food source for many migratory birds that breed in the Arctic. In cold environments, the growth and emergence of arthropods are particularly tied to temperature. Thus, the phenology of arthropods is anticipated to undergo a rapid change in response to a warming climate, potentially leading to a trophic mismatch between migratory insectivorous birds and their prey. Using data from 19 sites spanning a wide temperature gradient from the Subarctic to the High Arctic, we investigated the effects of temperature on the phenology and biomass of arthropods available to shorebirds during their short breeding season at high latitudes. We hypothesized that prolonged exposure to warmer summer temperatures would generate earlier peaks in arthropod biomass, as well as higher peak and seasonal biomass. Across the temperature gradient encompassed by our study sites (>10°C in average summer temperatures), we found a 3-day shift in average peak date for every increment of 80 cumulative thawing degree-days. Interestingly, we found a linear relationship between temperature and arthropod biomass only below temperature thresholds. Higher temperatures were associated with higher peak and seasonal biomass below 106 and 177 cumulative thawing degree-days, respectively, between June 5 and July 15. Beyond these thresholds, no relationship was observed between temperature and arthropod biomass. Our results suggest that prolonged exposure to elevated temperatures can positively influence prey availability for some arctic birds. This positive effect could, in part, stem from changes in arthropod assemblages and may reduce the risk of trophic mismatch.

Why do avian responses to change in Arctic green-up vary?

Global climate change has altered the timing of seasonal events (i.e., phenology) for a diverse range of biota. Within and among species, however, the degree to which alterations in phenology match climate variability differ substantially. To better understand factors driving these differences, we evaluated variation in timing of nesting of eight Arctic-breeding shorebird species at 18 sites over a 23-year period. We used the Normalized Difference Vegetation Index as a proxy to determine the start of spring (SOS) growing season and quantified relationships between SOS and nest initiation dates as a measure of phenological responsiveness. Among species, we tested four life history traits (migration distance, seasonal timing of breeding, female body mass, expected female reproductive effort) as species-level predictors of responsiveness. For one species (Semipalmated Sandpiper), we also evaluated whether responsiveness varied across sites. Although no species in our study completely tracked annual variation in SOS, phenological responses were strongest for Western Sandpipers, Pectoral Sandpipers, and Red Phalaropes. Migration distance was the strongest additional predictor of responsiveness, with longer-distance migrant species generally tracking variation in SOS more closely than species that migrate shorter distances. Semipalmated Sandpipers are a widely distributed species, but adjustments in timing of nesting relative to variability in SOS did not vary across sites, suggesting that different breeding populations of this species were equally responsive to climate cues despite differing migration strategies. Our results unexpectedly show that long-distance migrants are more sensitive to local environmental conditions, which may help them to adapt to ongoing changes in climate.

Unexpected diversity in socially synchronized rhythms of shorebirds.

The behavioural rhythms of organisms are thought to be under strong selection, influenced by the rhythmicity of the environment. Such behavioural rhythms are well studied in isolated individuals under laboratory conditions, but free-living individuals have to temporally synchronize their activities with those of others, including potential mates, competitors, prey and predators. Individuals can temporally segregate their daily activities (for example, prey avoiding predators, subordinates avoiding dominants) or synchronize their activities (for example, group foraging, communal defence, pairs reproducing or caring for offspring). The behavioural rhythms that emerge from such social synchronization and the underlying evolutionary and ecological drivers that shape them remain poorly understood. Here we investigate these rhythms in the context of biparental care, a particularly sensitive phase of social synchronization where pair members potentially compromise their individual rhythms. Using data from 729 nests of 91 populations of 32 biparentally incubating shorebird species, where parents synchronize to achieve continuous coverage of developing eggs, we report remarkable within- and between-species diversity in incubation rhythms. Between species, the median length of one parent's incubation bout varied from 1-19 h, whereas period length-the time in which a parent's probability to incubate cycles once between its highest and lowest value-varied from 6-43 h. The length of incubation bouts was unrelated to variables reflecting energetic demands, but species relying on crypsis (the ability to avoid detection by other animals) had longer incubation bouts than those that are readily visible or who actively protect their nest against predators. Rhythms entrainable to the 24-h light-dark cycle were less prevalent at high latitudes and absent in 18 species. Our results indicate that even under similar environmental conditions and despite 24-h environmental cues, social synchronization can generate far more diverse behavioural rhythms than expected from studies of individuals in captivity. The risk of predation, not the risk of starvation, may be a key factor underlying the diversity in these rhythms.

Genome Wide Conditional Mouse Knockout Resources.

The International Knockout Mouse Consortium (IKMC) developed high throughput gene trapping and gene targeting pipelines that produced mostly conditional mutations of more than 18,500 genes in C57BL/6N mouse embryonic stem (ES) cells which have been archived and are freely available to the research community as a frozen resource. From this unprecedented resource more than 6,000 mutant mouse strains have been produced by the IKMC and mostly the International Mouse Phenotyping Consortium (IMPC). In addition, a cre-driver resource was established including 250 inducible cre-driver mouse strains in a C57BL/6 background. Complementing the cre-driver resource, a collection of comprising 27 cre-driver rAAVs has also been produced. The resources can be easily accessed at the IKMC/IMPC web portal (www.mousephenotype.org). The IKMC/IMPC resource is a standardized reference library of mouse models with defined genetic backgrounds that enables the analysis of gene-disease associations in mice of different genetic makeup and should therefore have a major impact on biomedical research.

An impending crisis in the provision of histopathology expertise for mouse functional genomics.

The generation of new mouse models of human disease is accelerating rapidly, due to the completion of whole-genome sequencing efforts and technological advances in the manipulation of the mouse genome. We sought to investigate manpower issues in the provision of histopathology expertise for mouse functional genomics and compared this to the perceived demand from principal investigators (PIs). Through the European Commission (EC)-funded PRIME pathology training initiative, two questionnaires were devised to collect information from pathologists and EC-funded PIs on the current provision of mouse histopathology expertise in Europe and the demands for this service. We find that pathological analysis is being performed almost exclusively by professionally qualified pathologists, generally employed in clinical diagnostic posts, where the work is undertaken as collaboration outside of their contractual commitments but without previous training in veterinary or comparative pathology. The results indicate that there is a lack of both trainees and provision of specialist training in this field. Unsurprisingly, the availability of diagnostic expertise and advice falls far short of the number of genetically engineered mice (GEM) being generated for analysis. We analyse these results with reference to previous studies and discuss solutions for the future recruitment, training and funding for pathologists in mouse functional genomics in Europe.

Comment on "Global pattern of nest predation is disrupted by climate change in shorebirds".

Kubelka et al (Reports, 9 November 2018, p. 680) claim that climate change has disrupted patterns of nest predation in shorebirds. They report that predation rates have increased since the 1950s, especially in the Arctic. We describe methodological problems with their analyses and argue that there is no solid statistical support for their claims.

Effects of geolocators on hatching success, return rates, breeding movements, and change in body mass in 16 species of Arctic-breeding shorebirds.

BACKGROUND: Geolocators are useful for tracking movements of long-distance migrants, but potential negative effects on birds have not been well studied. We tested for effects of geolocators (0.8-2.0 g total, representing 0.1-3.9 % of mean body mass) on 16 species of migratory shorebirds, including five species with 2-4 subspecies each for a total of 23 study taxa. Study species spanned a range of body sizes (26-1091 g) and eight genera, and were tagged at 23 breeding and eight nonbreeding sites. We compared breeding performance and return rates of birds with geolocators to control groups while controlling for potential confounding variables. RESULTS: We detected negative effects of tags for three small-bodied species. Geolocators reduced annual return rates for two of 23 taxa: by 63 % for semipalmated sandpipers and by 43 % for the arcticola subspecies of dunlin. High resighting effort for geolocator birds could have masked additional negative effects. Geolocators were more likely to negatively affect return rates if the total mass of geolocators and color markers was 2.5-5.8 % of body mass than if tags were 0.3-2.3 % of body mass. Carrying a geolocator reduced nest success by 42 % for semipalmated sandpipers and tripled the probability of partial clutch failure in semipalmated and western sandpipers. Geolocators mounted perpendicular to the leg on a flag had stronger negative effects on nest success than geolocators mounted parallel to the leg on a band. However, parallel-band geolocators were more likely to reduce return rates and cause injuries to the leg. No effects of geolocators were found on breeding movements or changes in body mass. Among-site variation in geolocator effect size was high, suggesting that local factors were important. CONCLUSIONS: Negative effects of geolocators occurred only for three of the smallest species in our dataset, but were substantial when present. Future studies could mitigate impacts of tags by reducing protruding parts and minimizing use of additional markers. Investigators could maximize recovery of tags by strategically deploying geolocators on males, previously marked individuals, and successful breeders, though targeting subsets of a population could bias the resulting migratory movement data in some species.

Intercontinental genetic structure and gene flow in Dunlin (Calidris alpina), a potential vector of avian influenza.

Waterfowl (Anseriformes) and shorebirds (Charadriiformes) are the most common wild vectors of influenza A viruses. Due to their migratory behavior, some may transmit disease over long distances. Migratory connectivity studies can link breeding and nonbreeding grounds while illustrating potential interactions among populations that may spread diseases. We investigated Dunlin (Calidris alpina), a shorebird with a subspecies (C. a. arcticola) that migrates from nonbreeding areas endemic to avian influenza in eastern Asia to breeding grounds in northern Alaska. Using microsatellites and mitochondrial DNA, we illustrate genetic structure among six subspecies: C. a. arcticola,C. a. pacifica,C. a. hudsonia,C. a. sakhalina,C. a. kistchinski, and C. a. actites. We demonstrate that mitochondrial DNA can help distinguish C. a. arcticola on the Asian nonbreeding grounds with >70% accuracy depending on their relative abundance, indicating that genetics can help determine whether C. a. arcticola occurs where they may be exposed to highly pathogenic avian influenza (HPAI) during outbreaks. Our data reveal asymmetric intercontinental gene flow, with some C. a. arcticola short-stopping migration to breed with C. a. pacifica in western Alaska. Because C. a. pacifica migrates along the Pacific Coast of North America, interactions between these subspecies and other taxa provide route for transmission of HPAI into other parts of North America.

An improved invertebrate synaptosomal preparation with cholinergic properties.

Our laboratory has previously characterized a high affinity choline uptake system (HAChUS) in Limulus tissues and synaptosomes. We report here on the characterization of the HAChUS in synaptosomes prepared selectively from central nervous system tissues shown to be enriched for presumed cholinergic functions; namely the protocerebrum, corpora pedunculata and abdominal ganglia. Synaptosomes were prepared from these tissues by means of a modification of the subfractionation procedure developed by Dowdall and Whittaker. In our modification, we harvested a PP2L fraction exclusively from the S2 fraction. Compared to the P2L fraction, the PP2L was greater than three times more efficient in [3H]choline uptake and was significantly more sensitive to inhibition with micromolar concentrations of hemicholinium-3. The PP2L fraction HAChUS was shown to have characteristics common to the HAChUS of identified cholinergic tissues.

Anterior capsulotomy and continuous passive motion in the treatment of post-traumatic flexion contracture of the elbow. A prospective study.

Thirty-three patients who had a post-traumatic flexion contracture of the elbow were managed consecutively with anterior capsulotomy without tenotomy of the biceps tendon or myotomy of the brachialis muscle. The first fifteen patients (Group I) did not receive continuous passive motion postoperatively. Preoperative active extension for Group I was to an average of 48 degrees short of full extension, which improved to 19 degrees at a mean follow-up time of forty-five months. Subsequently, eighteen patients (Group II) received continuous passive motion postoperatively for a mean of six weeks. Preoperative active extension for Group II was to an average of 55 degrees short of full extension, which improved to 23 degrees at a mean duration of follow-up of thirty-five months. The mean preoperative arc of motion for Group I was 69 degrees, which improved to 94 degrees postoperatively. The mean preoperative arc of motion for Group II was 48 degrees, which improved to 95 degrees postoperatively. Five patients in Group I and six patients in Group II had severe preoperative heterotopic ossification. There was no correlation, however, between preoperative heterotopic ossification and the amount that extension of the elbow improved postoperatively. There was no postoperative increase in heterotopic ossification. Four patients in Group I and six patients in Group II had severe post-traumatic osteoarthrosis preoperatively. Anterior capsulotomy is an effective treatment of post-traumatic flexion contracture of the elbow. Although the postoperative use of continuous passive motion did not significantly improve mean active extension, it did improve active flexion and the total arc of motion.

Bone-grafting in total hip arthroplasty for protrusio acetabuli. A follow-up note.

The results of total hip arthroplasty with the use of medial and superior bone-graft augmentation in thirty-nine hips (thirty-two patients) that had protrusio acetabuli were previously reported after two to eight years (mean, 4.7 years) of follow-up. We followed the surviving patients for 10.9 to 17.4 years (mean, 12.8 years). The average Harris hip-rating was 72 points--an average drop of 17 points since the previous report. The average was 64 points for patients who had rheumatoid arthritis and 83 points for those who had another diagnosis. Radiographic evaluation demonstrated definite, probable, and possible loosening in about 20, 10, and 60 per cent of the hips, respectively. Of the six hips that had definite loosening, four (10 per cent of the total series) had progression of the protrusion (acetabular migration); operative revision was performed on two of those four hips and on two other hips, in which progression had ceased. Hips that had progressive protrusion demonstrated superior migration more often than medial migration. The rates of loosening and revision were similar to those in hips that did not have protrusio acetabuli. We concluded that augmentation of total hip arthroplasty with bone-grafting is effective in arresting the progression of protrusio acetabuli in most hips (90 per cent in our series).

Talar impingement by the anteroinferior tibiofibular ligament. A cause of chronic pain in the ankle after inversion sprain.

Seven patients who had pain in the anterior aspect of the ankle were found to have a thickened distal fascicle of the anteroinferior tibiofibular ligament. Each patient had a history of an inversion sprain of the ankle followed by chronic pain in the anterior aspect of the ankle. The thickened distal fascicle was resected without loss of stability of the ankle. Five patients needed débridement of an area of abraded hyaline cartilage on the anterolateral aspect of the talus. Six patients were followed for a mean of thirty-nine months (range, twenty-four to fifty-nine months). Four of them had no pain in the ankle or limitation in activities, and two reported marked improvement, with only occasional pain in the ankle related to overuse. A separate distal fascicle of the anteroinferior tibiofibular ligament is present in most human ankles and can be a cause of talar impingement, abrasion of the articular cartilage, and pain in the anterior aspect of the ankle. Resection of this ligament usually will alleviate the pain caused by the impingement.

Severe open subtalar dislocations. Long-term results.

Fifteen adolescents and adults were assessed an average of eighteen years after a type-III open subtalar dislocation. There were ten lateral and five medial dislocations. Associated injuries included ten injuries of the tibial nerve, seven of which were complicated by causalgia; five ruptures of the posterior tibial tendon; five lacerations of the posterior tibial artery; twelve articular fractures involving the subtalar joint; three articular fractures of the talonavicular joint; three fractures of the talar dome; and three malleolar fractures. Osteonecrosis of the body of the talus was found in five of the fifteen patients. It was treated with a triple arthrodesis in all five patients, one of whom had a subsequent conversion to a pantalar arthrodesis. Subtalar arthrodesis was done, because of post-traumatic osteoarthrosis, in two other patients. On functional assessment at the long-term follow-up examination, all patients reported some pain in the ankle, nine had difficulty climbing stairs, fourteen had difficulty walking on uneven surfaces, and eleven wore modified shoes. The patients who had had a tarsal arthrodesis returned to their pre-injury occupation or to a less strenuous job. Four patients who had persistent causalgia did not return to work. We concluded that open subtalar dislocation is a distinctly severe injury and that only fair functional and poor anatomical results can be expected in most patients.

Pneumocystis carinii pneumonia in pregnancy. A case report.

The association of human immunodeficiency virus (HIV) infection and pregnancy has become more common. This virus has become a factor in the social affairs of even small, rural communities. We present a case in which the diagnosis of HIV was made during admission for Pneumocystis carinii pneumonia (PCP). The patient's condition worsened rapidly, necessitating delivery at 31 weeks' gestation by cesarean section followed by the patient's death from PCP. The infant survived and was healthy at 1 year of age.

The use of magnetic resonance imaging in the diagnosis of pigmented villonodular synovitis.

Although the clinical and radiographic features of pigmented villonodular synovitis (PVS) have been well described, diagnosis is often delayed and high rates of recurrence after synovectomy are reported. Magnetic resonance imaging (MRI) has been shown to be useful in the diagnosis of soft tissue masses. Three patients with biopsy-proven PVS and radiographs showing only effusion underwent MRI in the axial, coronal, and sagittal planes. The margins of the diseased synovium were best demonstrated on long TR/TE (T2-weighted) images. The synovium contained areas of void signal intensity felt to be due to hemosiderin, interspersed with increased signal from both inflammation and fat. In all cases, the margins of the diseased synovium were clearly delineated, allowing classification as nodular or diffuse. No appreciable change in signal intensity was seen when comparing nodular and diffuse forms. MRI is useful but not specific for PVS, since rheumatoid synovitis may show a similar signal pattern. However, MRI in patients with suspected PVS may decrease the time until diagnosis, aid in preoperative planning and obtaining adequate margins of resection, and may be a non-invasive method of long-term follow up for possible recurrence.

Vascular endothelial growth factor (VEGF) and VEGF receptor expression in biopsy samples of liver from dogs with congenital portosystemic shunts.

Surgical attenuation of a congenital portosystemic shunt (CPSS) results in increased liver mass, development of intrahepatic portal vasculature and improved liver function. Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. The aim of this study was to investigate the role of VEGF and its receptor in the hepatic response to CPSS surgery. The study included 99 dogs with CPSS treated with either partial or complete suture attenuation. Forty-four dogs with partial attenuation underwent a second surgery for complete attenuation. The expression of VEGF and VEGF receptor 2 (VEGFR2) in biopsy samples of liver was assessed by immunohistochemistry with rabbit anti-human VEGF polyclonal antibody and mouse anti-human VEGFR2 monoclonal antibody. Expression of these molecules was graded. The proportion of samples expressing VEGF was significantly greater in samples from dogs with CPSS compared with control samples (P=0.04) and the proportion of samples expressing VEGFR2 was significantly greater in control samples compared with samples from dogs with CPSS (P=0.04). VEGF labelling grade decreased significantly (P=0.038) and VEGFR2 increased significantly (P=0.046) between first and second surgery. The decrease in VEGF may reflect transient expression, preferential expression of other factors, reperfusion of existing vessels and/or increased angiogenesis before surgery in the form of arterialization and subsequent reduction due to improved portal blood flow. Partial suture attenuation was associated with a degree of 'normalization' of VEGF and VEGFR2 expression when compared with the control samples. Further investigation is needed to provide more information on the hepatic response to CPSS surgery.

The importance of competition between motoneurones in developing rat muscle; effects of partial denervation at birth.

1. The number of motor units in developing fourth deep lumbrical muscles was reduced by unilateral partial denervation of the muscle at birth, by cutting the lateral plantar nerve. A minority of the motor axons arrive via the sural nerve, and were thus not cut. Those muscles that contained one motor unit (one-unit muscles) after partial denervation developed in the absence of competition between motoneurones. Muscles with two motor units had little competition. A few four-unit muscles were studied for comparison. 2. Isometric twitch and tetanic tensions of single motor units were recorded in vitro at 60 days of age in response to stimulation of the sural nerve. On average, units in partially denervated muscles generated more tension than normal units. The isometric tension characteristics of the units in the one-unit and two-unit muscles were different from the normal units (e.g. slower contracting and more fatiguable). The units of four-unit muscles had properties similar to those of normal muscles. 3. Fibres of an individual unit were identified by glycogen depletion and S (slow) fibres were identified in cross-section that bound a polyclonal antibody to slow type I myosin. Those fibres that did not bind the antibody were designated F fibres. The units of one-unit muscles had the same total number of fibres and fibre type composition (both S and F fibres in the same unit) as estimated from previous work to exist at birth. The units of two-unit muscles contained the same total number of fibres, but apparently fewer S fibres, though this may have been as a result of incomplete glycogen depletion of some fibres. 4. It is concluded that competition between motoneurone terminals is necessary for the withdrawal of mismatched connections on muscle fibres present at birth; or, alternatively, that such withdrawal cannot take place if it would result in denervation of the muscle fibre.

Spatial distribution of muscle fibers in a lumbrical muscle of the rat.

The spatial distributions of two different populations of muscle fibers were measured in cross-sections taken from the mid-belly of adult 4DL muscles. Muscle fibers belonging to a single motor unit (identified by glycogen depletion) were distributed randomly in most muscles. Muscle fibers which contained slow myosin (identified immunohistochemically) were distributed nonrandomly, being evenly distributed throughout most of the muscle cross-section, but excluded from the edge of the muscle. Interpreted from a developmental perspective, the results are consistent with the proposals that slow myosin-containing fibers in the adult represent the original population of primary myotubes, and that the adult pattern of motor unit fiber type is achieved by synapse elimination from mismatched fibers rather than by conversion of fiber type.

Uterine cancer screening by the family physician.

Endometrial diagnostic techniques available to the family physician for office use have a high degree of accuracy in identifying intrauterine pathology. Recent refinements in endometrial sampling devices have made their use cost-effective and complication rates minimal. These methods can be utilized annually for screening asymptomatic women at high risk of developing uterine cancer. Detection of endometrial hyperplasia has improved with the newer samplers. Patient acceptance is excellent, especially with the cytologic devices.