•A broth dilution procedure for AST of Brachyspira species is described.•The broth dilution method was validated in a ring trial.•Intra- and inter-laboratory reproducibility was good.•New control ...strains are proposed.•Increased MIC corresponded to genomic data indicating decreased susceptibility.
Brachyspira hyodysenteriae and Brachyspira pilosicoli cause economically important enteric disease in pigs. Treatment of these infections often includes antimicrobial administration, which can be most effective when therapeutic options are informed by antimicrobial susceptibility testing data. Here we describe a method for broth dilution antimicrobial susceptibility testing of these bacteria, both of which are difficult to culture in vitro. The protocol was evaluated for its fitness for use in an inter-laboratory ring trial involving eight laboratories from seven countries, and employing eleven test strains (5 Brachyspira hyodysenteriae including the type strain B78T and 6 Brachyspira pilosicoli) and six antibiotics. Overall intra- and inter-laboratory reproducibility of this method was very good (>90 % MICs at mode +/- 1 log2). Whole genome sequencing revealed good correspondence between reduced susceptibility and the presence of previously defined antimicrobial resistance determinants. Interestingly, lnu(C) was identified in B. pilosicoli isolates with elevated MICs of lincomycin, whilst tva(B) was associated with elevated MICs of pleuromutilins in this species. We designated two new control strains with MICs lying within currently tested ranges, including for the pleuromutilins, in contrast to the control strain B. hyodysenteriae B78T. These were deposited at the DSMZ-German Collection of Microorganisms and Cell Cultures GmbH. The validation of a standard protocol and identification of new control strains facilitates comparisons between studies, establishment of robust interpretative criteria, and ultimately contributes to rational antimicrobial use when treating infected livestock.
Biodiversity loss is a major global challenge of the 21st century. Ultimately, extinctions of species are determined by birth and death rates; thus, conservation management of at-risk species is ...dependent on robust demographic data. In this study, data gathered from 381 (227 females, 154 males) long-finned pilot whales (Globicephala melas edwardii) that died in 14 stranding events on the New Zealand coast between 2006 and 2017 were used to construct the first age- and sex-specific life tables for the subspecies. Survivorship curves were fitted to these data using (1) a traditional maximum likelihood approach, and (2) Siler's competing-risk model. Life table construction and subsequent survival curves revealed distinct differences in the age- and sex-specific survival rates, with females outliving males. Both sexes revealed slightly elevated rates of mortality among the youngest age-classes (<2 years) with postweaning mortality rates decreasing and remaining relatively low until the average life expectancy is reached; 11.3 years for males and 14.7 years for females. Overall (total) mortality is estimated to be 8.8% and 6.8% per annum for males and females, respectively. The mortality curve resembles that of other large mammals, with high calf mortality, lower postweaning mortality, and an exponentially increasing risk of senescent mortality. An accelerated mortality rate was observed in mature females, in contrast to the closely related short-finned pilot whale (G. macrorhynchus), which selects for an extension to the postreproductive life span. The reason for the observed differences in the mortality rate acceleration and postreproductive life span between the two pilot whale species have not been established and warrant further investigation. Obtaining robust information on the life history of long-lived species is challenging, but essential to improve our understanding of population dynamics and help predict how future pressures may impact populations. This study illustrates how demographic data from cetacean stranding events can improve knowledge of species survival rates, thus providing essential information for conservation management.
Knowledge of population biological parameters can contribute to assessing the resilience of a population in the face of increasing anthropogenic pressures. Southern Hemisphere long-finned pilot ...whales (Globicephala melas edwardii) are susceptible to high rates of live stranding-related mortality. However, the biological parameters of this population largely are unknown. In this study, age, growth, allometry, and sexual dimorphism are described using teeth and external body measurements obtained from 515 male, 776 female, and 229 individuals of unknown sex, stranded on the New Zealand coastline between 1948 and 2017. Maximum ages of 31 and 38 years were estimated for males (n = 163) and females (n = 239), respectively. Females ranged in length from 160 to 500 cm (modal size class 400–449 cm) and males from 165 to 622 cm (modal size class 500–549 cm). Length-at-birth for both sexes was estimated at 170 cm using a logistic regression model. Growth models for both sexes indicated a preliminary rapid growth phase followed by a second phase of slower growth. For males, a two-phase growth model also indicated a moderate growth spurt around the average age at attainment of sexual maturity (ca.12–13 years). Asymptotic lengths were estimated at 570 and 438 cm for males and females, respectively. We found strong evidence of sexual size dimorphism, with males significantly larger than females for 13 of 14 external measurements. We also found sexual dimorphism with respect to shape, with males having proportionally longer pectoral fins, wider tail flukes, and taller dorsal fins, than females. Estimates of length-at-birth, maximum ages, and sexual shape dimorphism for G. m. edwardii differed from those previously reported for the North Atlantic subspecies (G. m. melas), which may indicate subspecies or population-level differences in morphology, longevity, and sociality.
Production of nitrogenous waste by livestock agriculture is a significant environmental concern in terms of pollution of land and water. In the rumens of cattle and sheep, the excessive proteolysis ...which contributes to inefficiency of nutrient use involves both the rumen microbial population and the intrinsic plant proteases that can mediate protein degradation in ingested fresh forage on exposure to the environmental stresses of the rumen. Here, white clover (Trifolium repens) plants that do not form root nodules, and so are dependent on nitrate supplied to the roots, have been used to determine how nitrogen status of the plant affects the rate of plant‐mediated proteolysis in forage under conditions that simulate ingestion by grazing ruminants. Plants were grown from seed and supplied with nutrient solution containing 2.5, 5.0, 7.5 or 10 mM nitrate. Protein, free amino acid and protease activity were determined in leaves which had been placed in an in vitro system designed to simulate conditions experienced in the rumen (anaerobic phosphate buffer maintained at 39°C in the dark). Foliar protein content increased with increasing nitrate supply, while in vitro incubation of leaves resulted in time‐dependent decreases in protein concentration and increases in amino acid concentration. Regardless of nitrate supply, 50% of the protein was degraded in 6 h and 80% after 24 h. As the extent of protein decrease was determined by initial protein content, more protein degradation occurred in those plants grown with the highest nitrate supply: after 6 h, 130.7 mg g−1 dry matter (DM) was degraded in leaves grown at 10 mM nitrate but only 52.3 mg g−1 DM in leaves grown at 2.5 mM nitrate. Hence, although the percentage of proteolysis is independent of foliar protein concentration, the latter is critical to the quantity of protein degraded. Heat‐stable serine and cysteine proteases were active throughout the term of the in vitro incubation. Although proteolysis in ingested forage can continue for many hours, mediated by heat‐stable proteases, maximum amino acid accumulation accounted for less than 40% of initial protein. Therefore, it is proposed that continued and extensive proteolysis occurs following leaf excision and exposure to rumen conditions because amino acid accumulation is insufficient to initiate those feedback systems which sense cytoplasmic amino acid concentration and prevent excessive proteolysis during normal source–sink relations.
Preen gland secretions were obtained from several hens that were rearing their chicks and the content of these secretions was analysed. From these results, a synthetic analogue of the secretions was ...created (given the title Mother Hen Uropygial Secretion Analogue, or MHUSA, in this study). According to a blinded, controlled experimental design, heavy broilers (strain SASSO T56N) were reared from 1 day of age in an environment treated with either MHUSA or control. At 80 days the birds were slaughtered. Post mortemcarcass weight, abdominal fat and fillet weights were then measured. Colour, pH and yield were also measured as indicators of meat quality. Broilers exposed to MHUSA had both higher carcass weights and higher fillet weights compared with control-treated birds (P < 0.05). Abdominal fat, pH, water loss and colorimetry results were similar between the treatment groups at all time points (24 h and 6 days post mortem) and also after a cooking procedure. The meat from the MHUSA birds was less yellow compared with control. It is concluded that constant exposure to MHUSA from rearing until slaughter improves growth rate in broilers without significantly affecting meat quality.
Programmed plant cell death is a widespread phenomenon resulting in the formation of xylem vessels, dissected leaf forms, and aerenchyma. We demonstrate here that some characteristics of programmed ...cell death can also be observed during the cellular response to biotic and abiotic stress when plant tissue is ingested by grazing ruminants. Furthermore, the onset and progression of plant cell death processes may influence the proteolytic rate in the rumen. This is important because rapid proteolysis of plant proteins in ruminants is a major cause of the inefficient conversion of plant to animal protein resulting in the release of environmental N pollutants. Although rumen proteolysis is widely believed to be mediated by proteases from rumen microorganisms, proteolysis and cell death occurred concurrently in clover leaves incubated in vitro under rumenlike conditions (maintained anaerobically at 39 degrees C) but in the absence of a rumen microbial population. Under rumenlike conditions, both red and white clover cells showed progressive loss of DNA, but this was only associated with fragmentation in white clover. Cell death was indicated by increased ionic leakage and the appearance of terminal deoxynucleotidyl transferase-mediated dUTP-nick-end-labelled nuclei. Foliar protein decreased to 50% of the initial values after 3 h incubation in white clover and after 4 h in red clover, while no decrease was observed in ambient (25 degrees C, aerobic) incubations. In white clover, decreased foliar protein coincided with an increased number of protease isoforms.
Using data on formal manufacturing plants in India, we report a large but imprecise speedup in productivity growth starting in the early 1990s (e.g., 1993-2007 compared to 1980-1992). We trace it to ...productivity growth within large plants (200 workers or more), as opposed to reallocation across such plants. As many economists believe Indian reforms during this era improved resource allocation, the absence of a growth pickup from reallocation is surprising. Moreover, when we look across industries we fail to robustly relate productivity growth to prominent reforms such as industrial de-licensing, tariff reductions, FDI liberalization, or lifting of small-scale industry reservations. Even under a generous reading of their effects, these reforms (at least as we measure them) account for less than one-third of the rapid productivity growth in Indian manufacturing from 1980-2007. All rights reserved, Elsevier
Recorded remittances to Africa have grown dramatically over the past decade. Yet data limitations still mean relatively little is known about which migrants remit, how much they remit and how their ...remitting behaviour varies with gender, education, income levels and duration abroad. This paper constructs the most comprehensive remittance database currently available on immigrants in the OECD, containing microdata on more than 12,000 African immigrants. Using this microdata the authors establish several basic facts about the remitting patterns of Africans, and then explore how key characteristics of policy interest relate to remittance behaviour. Africans are found to remit twice as much on average as migrants from other developing countries, and those from poorer African countries are more likely to remit than those from richer African countries. Male migrants remit more than female migrants, particularly among those with a spouse remaining in the home country; more-educated migrants remit more than less educated migrants; and although the amount remitted increases with income earned, the gradient is quite flat over a large range of income. Finally, there is little evidence that the amount remitted decays with time spent abroad, with reductions in the likelihood of remitting offset by increases in the amount remitted conditional on remitting.
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