A new species of Halacarsantia Wolff, 1989 (Crustacea, Isopoda, Asellota, Santiidae) from Wistari Reef, southern Great Barrier Reef, Australia

Halacarsantia acutasp. n. is described from Wistari Reef, Capricorn Group, southern Great Barrier Reef, the first record of the genus from Australia. The new species differs from its congeners in having antenna flagellum composed of 8 articles; epipod apically acute, without setae, broad maxilliped endite and pereopod 1 basis with a short projection. A key to species of the genus is provided.     

Thermophilic biohydrogen production: how far are we?

Apart from being applied as an energy carrier, hydrogen is in increasing demand as a commodity. Currently, the majority of hydrogen (H₂) is produced from fossil fuels, but from an environmental perspective, sustainable H₂ production should be considered. One of the possible ways of hydrogen production is through fermentation, in particular, at elevated temperature, i.e. thermophilic biohydrogen production. This short review recapitulates the current status in thermophilic biohydrogen production through fermentation of commercially viable substrates produced from readily available renewable resources, such as agricultural residues. The route to commercially viable biohydrogen production is a multidisciplinary enterprise. Microbiological studies have pointed out certain desirable physiological characteristics in H₂-producing microorganisms. More process-oriented research has identified best applicable reactor types and cultivation conditions. Techno-economic and life cycle analyses have identified key process bottlenecks with respect to economic feasibility and its environmental impact. The review has further identified current limitations and gaps in the knowledge, and also deliberates directions for future research and development of thermophilic biohydrogen production.     

Social contacts and mixing patterns relevant to the spread of infectious diseases

Background

Mathematical modelling of infectious diseases transmitted by the respiratory or close-contact route (e.g., pandemic influenza) is increasingly being used to determine the impact of possible interventions. Although mixing patterns are known to be crucial determinants for model outcome, researchers often rely on a priori contact assumptions with little or no empirical basis. We conducted a population-based prospective survey of mixing patterns in eight European countries using a common paper-diary methodology.

Methods and Findings

7,290 participants recorded characteristics of 97,904 contacts with different individuals during one day, including age, sex, location, duration, frequency, and occurrence of physical contact. We found that mixing patterns and contact characteristics were remarkably similar across different European countries. Contact patterns were highly assortative with age: schoolchildren and young adults in particular tended to mix with people of the same age. Contacts lasting at least one hour or occurring on a daily basis mostly involved physical contact, while short duration and infrequent contacts tended to be nonphysical. Contacts at home, school, or leisure were more likely to be physical than contacts at the workplace or while travelling. Preliminary modelling indicates that 5- to 19-year-olds are expected to suffer the highest incidence during the initial epidemic phase of an emerging infection transmitted through social contacts measured here when the population is completely susceptible.

Conclusions

To our knowledge, our study provides the first large-scale quantitative approach to contact patterns relevant for infections transmitted by the respiratory or close-contact route, and the results should lead to improved parameterisation of mathematical models used to design control strategies.     

Reappraisal of the Regulation of Lactococcal l-Lactate Dehydrogenase

Lactococcal lactate dehydrogenases (LDHs) are coregulated at the substrate level by at least two mechanisms: the fructose-1,6-biphosphate/phosphate ratio and the NADH/NAD ratio. Among the Lactococcus lactis species, there are strains that are predominantly regulated by the first mechanism (e.g., strain 65.1) or by the second mechanism (e.g., strain NCDO 2118). A more complete model of the kinetics of the regulation of lactococcal LDH is discussed.     

Formation and conversion of oxygen metabolites by Lactococcus lactis subsp. lactis ATCC 19435 under different growth conditions

A semidefined medium based on Casamino Acids allowed Lactococcus lactis ATCC 19435 to grow in the presence of oxygen at a slow rate (0.015 h(-1)). Accumulation of H(2)O(2) in the culture prevented a higher growth rate. Addition of asparagine to the medium increased the growth rate, whereby H(2)O(2) accumulated only temporarily during the lag phase. H(2)O(2) is an inhibitor for several glycolytic enzymes, glyceraldehyde-3-phosphate dehydrogenase being the most sensitive. Strain ATCC 19435 contained NADH oxidase (maximum specific rate under aerobic conditions, 426 nmol of NADH min(-1) mg of protein(-1)), which reduced oxygen to water, whereby superoxide was formed as a by-product. H(2)O(2) originated from the dismutation of superoxide by superoxide dismutase. Although H(2)O(2) was rapidly destroyed under high metabolic fluxes, neither NADH peroxidase nor any other enzymatic H(2)O(2)-reducing activity was detected. However, pyruvate, the end product of glycolysis, reacted nonenzymatically and rapidly with H(2)O(2) and hence was a potential alternative for scavenging of this oxygen metabolite intracellularly. Indeed, intracellular concentrations of up to 93 mM pyruvate were detected in aerobic cultures growing at high rates. It is hypothesized that self-generated pyruvate may serve to protect L. lactis strain ATCC 19435 from H(2)O(2).     

Cultivation technology development of Rhodothermus marinus DSM 16675

Extremophiles - This work presents an evaluation of batch, fed-batch, and sequential batch cultivation techniques for production of R. marinus DSM 16675 and its exopolysaccharides (EPSs) and...     

A Household-Based Study of Contact Networks Relevant for the Spread of Infectious Diseases in the Highlands of Peru

Background

Few studies have quantified social mixing in remote rural areas of developing countries, where the burden of infectious diseases is usually the highest. Understanding social mixing patterns in those settings is crucial to inform the implementation of strategies for disease prevention and control. We characterized contact and social mixing patterns in rural communities of the Peruvian highlands.

Methods and Findings

This cross-sectional study was nested in a large prospective household-based study of respiratory infections conducted in the province of San Marcos, Cajamarca-Peru. Members of study households were interviewed using a structured questionnaire of social contacts (conversation or physical interaction) experienced during the last 24 hours. We identified 9015 reported contacts from 588 study household members. The median age of respondents was 17 years (interquartile range [IQR] 4–34 years). The median number of reported contacts was 12 (IQR 8–20) whereas the median number of physical (i.e. skin-to-skin) contacts was 8.5 (IQR 5–14). Study participants had contacts mostly with people of similar age, and with their offspring or parents. The number of reported contacts was mainly determined by the participants’ age, household size and occupation. School-aged children had more contacts than other age groups. Within-household reciprocity of contacts reporting declined with household size (range 70%-100%). Ninety percent of household contact networks were complete, and furthermore, household members'' contacts with non-household members showed significant overlap (range 33%-86%), indicating a high degree of contact clustering. A two-level mixing epidemic model was simulated to compare within-household mixing based on observed contact networks and within-household random mixing. No differences in the size or duration of the simulated epidemics were revealed.

Conclusion

This study of rural low-density communities in the highlands of Peru suggests contact patterns are highly assortative. Study findings support the use of within-household homogenous mixing assumptions for epidemic modeling in this setting.     

2,5-Disubstituted pyridines: the discovery of a novel series of 5-HT2A ligands

This report describes the effect of replacing the central basic amine present in many known 5-HT(2A) ligands with an aromatic residue. We targeted the isomeric phenethylpyridines 2 and 3 and these compounds proved to be excellent leads, possessing good 5-HT(2A) receptor binding affinity and selectivity over the 5-HT(2C) subtype. Optimization of one isomer led to the identification of 25, a compound with sub-nanomolar 5-HT(2A) affinity and selectivity over 5-HT(2C) of greater than 4600-fold.