An outbreak of Shiga toxin‐producing Escherichia coli O157:H7 linked to a mud‐based obstacle course,England, August 2018

In August 2018, Public Health England (PHE) was made aware of five probable cases of Shiga toxin‐producing Escherichia coli (STEC) O157:H7 among individuals reporting participation in a mud‐based obstacle race. An additional four cases, identified via routine whole‐genome sequencing, were subsequently linked to the same event. Two of the nine cases were due to secondary household transmission. Despite an agreement between the event organizers and the local authority, to ensure that all livestock were removed from the site 28 days before the event, sheep were observed grazing on some of the routes taken by the runners 2 days prior to the race taking place. A retrospective review of incidents reported to PHE between 2015 and 2018 identified 41 cases of gastroenteritis associated with muddy assault course events. Of these, 25 cases were due to infection with STEC O157:H7, of which all but one were associated with outbreaks. Due to the environment in which such events take place, it is impossible to entirely remove the risk of exposure to potentially pathogenic zoonoses. However, race organizers should ensure that livestock are removed from the course 28 days before the event. They should also ensure that participants are made aware of the risk of contracting gastrointestinal disease from the environment, and to stress the importance of hand hygiene post‐event and the risk of secondary transmission, particularly to children who are at risk of developing haemolytic uraemic syndrome.     

Wafer-scale graphene integrated circuit

A wafer-scale graphene circuit was demonstrated in which all circuit components, including graphene field-effect transistor and inductors, were monolithically integrated on a single silicon carbide wafer. The integrated circuit operates as a broadband radio-frequency mixer at frequencies up to 10 gigahertz. These graphene circuits exhibit outstanding thermal stability with little reduction in performance (less than 1 decibel) between 300 and 400 kelvin. These results open up possibilities of achieving practical graphene technology with more complex functionality and performance.     

A comparison of human chorionic gonadotropin and luteinizing hormone releasing hormone analogue for ovulation induction in black sea bass Centropristis striata (Linnaeus, 1758)

Mature black sea bass, Centropristis striata L. (200–800 g), were captured in coastal South Carolina during the spawning season and administered hormones for ovulation induction and strip spawning. During both study years, control groups of females were incorporated into the study design and administered sham injections containing physiological saline solution. In 2004, females received a single intramuscular injection of human chorionic gonadotropin (hCG) (330 IU kg⁻¹) (n=8) or two injections of hCG at 24‐h intervals (n=8). In 2005, females received a single injection of hCG (n=10) or an analogue of luteinizing hormone releasing hormone (LHRHa) (n=10). In 2004, all fish administered a single dose of hCG ovulated at least once. Six fish ovulated on two consecutive days and one fish ovulated on 3 days consecutively. In contrast, six of eight fish receiving two doses of hCG ovulated once, five ovulated on 2 days successively and three fish ovulated 3 days in succession. Of the fish that spawned, no differences were found in any reproductive parameters. In 2005, all fish administered hCG or LHRHa ovulated at least once. Three fish administered hCG ovulated twice, four fish ovulated on three consecutive days and one fish 4 days successively. All fish administered LHRHa spawned at least twice, six fish ovulated thrice and three fish ovulated 4 days, successively. A significant difference in fertility was found between hCG (75.6±11.4%) and LHRHa (55.6±27.4%). The results of this study indicate that both hCG and LHRHa are effective for ovulation induction in prespawning black sea bass.     

The effect of salinity on growth and survival of juvenile black bream (Acanthopagrus butcheri)

Growth and survival of juvenile black bream (Acanthopagrus butcheri) were determined at salinities from 0 to 60 ppt (in 12-ppt increments) and from 0 to 12 ppt (in 4-ppt increments) in two separate trials of 6 and 4 months duration, respectively. Juvenile black bream were able to survive and grow at salinities ranging from freshwater (0 ppt) to 48 ppt. Osmotic stress was evident at 60 ppt, however, survival was not significantly affected. Fish reared at 24 ppt in trial 1 had a specific growth rate of 2.34±0.03%/day, a rate significantly higher only to those fish reared at 60 ppt (2.16±0.04%/day). Growth was greater at 24 ppt in association with the highest food intake and most efficient FCR. Although both food intake and FCR were not significantly higher than those obtained with fish reared at 12, 36 and 48 ppt, the combination of the two factors being optimised at 24 ppt lead to the greatest growth. Analysis of data from the second trial found no significant difference in the growth rate of black bream reared at salinities ranging from freshwater to 12 ppt, with SGR ranging from 1.92±0.05%/day to 2.05±0.02%/day. Variable results in freshwater between the two trials suggested that total hardness of freshwater may influence survival and/or an ontogenetic change in salinity tolerance may occur.     

Economic feasibility of prawn Macrobrachium production in South Carolina,USA

Cost and returns were estimated for freshwater prawn Macrobrachium rosenbergii farming as a supplemental enterprise in South Carolina in relation to the following factors: (1) existing versus new investment for ponds and water supply; (2) three stocking strategies (postlarvae alone, a 50:50 mixture of postlarvae and nursed juveniles and nursed juveniles alone) at various densities (2·15–8·61 prawns m^?2); (3) a range of prices for seed stock ($0–50 per thousand); and (4) two marketing alternatives (sale of product as shrimp tails only or with the large animals marketed heads-on and the rest as tails). Net revenue estimates indicate that prawn aquaculture has potential to become a source of supplemental income to farmers in the coastal plain area of South Carolina and throughout much of the southeastern United States. This is especially likely if the enterprise can utilize existing pond facilities that are already discounted into the value of the land or were constructed during a period of lower investment costs. A prawn farm is unlikely to be profitable if postlarvae alone are stocked, even in existing facilities, but if a mixture of postlarvae and juveniles or juveniles alone are stocked in existing facilities, profitability is likely at seed costs up to about $40 per thousand.     

Evaluation of genetic variances, heritabilities, and correlations for yield and fiber traits among cotton F2 hybrid populations

Summary F₂ hybrid cultivars continue to occupy a small portion of the cotton (Gossypium hirsutum L.) production are in the United States, but occupy a larger proportion of the production area in some other countries. Sixty-four F₂ hybrids resulting from crosses of four commercial cultivars and 16 pest-resistant germplasm lines were evaluated for five fiber and four yield traits in four environments at Mississippi State, MS. An additive-dominance genetic model was employed for these traits. The minimum norm quadratic unbiased estimation (MINQUE) method was used with a mixed model approach for estimating genetic variance and covariance components and for predicting genetic correlations. This study investigated genetic variances, heritabilities, and genetic and phenotypic correlations between agronomic and fiber traits among these 64 F₂ hybrid populations and discussed the usefulness of these populations for use as hybrids or for selections for pure lines.Dominance variance accounted for the major proportion of the phenotypic variances for lint yield, lint percentage, and boll size indicating that hybrids should have an advantage for these traits compared to pure lines. A low proportion of additive variance for fiber traits and the significant additive x environment variance components indicated a lack of substantial useful additive genetic variability for fiber traits. This suggests that selections for pure lines within these F₂ populations would have limited success in improving fiber traits. Genetic and phenotypic correlation coefficients were of comparable magnitude for most pairs of characters. Fiber strength showed a positive additive genetic correlation with boll weight. Dominance genetic correlations of fiber strength with elongation and 2.5% span length were also significant and positive; however, the additive genetic correlation of length and strength was zero.Contribution of the USDA-ARS in cooperation with the Mississippi Agric. and Forestry Exp. Stn.     

Effects of chromosome 5sh from Gossypium barbadense L. on flower production in G. hirsutum L.

Cotton (Gossypium spp.) yield is directly determined by mature bolls that developed from squares and flowers. The first four to six weeks of flowering accounts for the majority of lint yield in upland cotton (G. hirsutum L.) for most cultivated areas of the southern USA cotton belt. In this study, we evaluated 13 cotton chromosome substitution lines (CS-B) and their chromosome specific-F₂ hybrids, TM-1, 3–79, and six cultivars for the number of flowers produced during the first four weeks of flowering. Results showed that CS-B05sh produced more flowers than TM-1 and 3–79 from 10 July to 5 August. The results suggest that when the short arm of chromosome 5 was substituted from 3–79 (G. barbadense L.) into TM-1 (G. hirsutum) a positive genetic association with flower numbers during this flowering period was exhibited. CS-B05sh had comparable flower numbers with three cultivars, Deltapine 90, Phytogen 355, and Stoneville 474 and more flowers than, Sure Grow 747, Sure Grow 125, and Deltapine 5415. Different patterns for additive and dominance effects on cumulative flowers were observed across weeks of flowering. Dominance effects were more apparent during the early part of the flowering period while additive effects were more apparent towards the end of the flowering period.     

Grain shedding in oats

Summary Results of observations on grain shedding in spring oats are presented for the seasons 1966, 1967 and 1968. These observations were made in field studies and also in laboratory tests using specially designed equipment, which is described in detail.A delay in harvesting, of approximately one month, resulted in mean grain losses in field trials of 13 per cent in 1967 and 23 per cent in 1968. Large varietal differences in grain shedding were observed in laboratory tests. There was no correlation between the grain shedding of varieties in the laboratory and their grain loss in the field in 1967, when the latter was estimated from small samples but laboratory and field results were highly correlated, positively, in 1968 when field losses were estimated from whole plots.The relative performance of varieties in laboratory tests was not substantially affected by the period of storage of the material or by the severity of the test applied. The relative grain shedding of varieties in laboratory tests was similarly unaffected by the date of harvest of the material, provided that ripe samples were taken.The proportion of grain shed in laboratory tests was negatively correlated with time from sowing to panicle emergence in 1967 and 1968. In both seasons, however, some varieties of identical maturity were differentiated in their grain shedding tendencies.The application of the laboratory technique to the screening of breeding material is discussed.     

Segregation of Isozyme Marker Loci Amongst Androgenetic Plants of Lolium perenne L.

The segregation of isozyme markers has been examined in the green and albino androgentic progenies of two plants of Lolium perenne. Overall the pooled data for the loci PG1/2 and GOT/2 does not deviate from expectation, but there is considerable heterogeneity between families and between green and albino plants. Specific alleles predominate in the different progeny sets. The results may be accounted for by possible linked loci affecting anther culture response or of linked lethal genes.