Evaluation of a remotely operated vehicle (ROV) as a tool for studying the distribution and abundance of zooplankton

Conventional methods for measuring zooplankton distributionsare too laborious and time consuming to permit sufficient temporaland spatial resolution in many instances. An ability to makemore efficient and precise measurements would be useful. Weevaluated the potential for using the video system of a commerciallyavailable remotely operated vehicle (ROV) to measure the distributionand abundance of zooplankton by calibrating ROV counts withcounts based on a conventional sampling procedure (a Schindlertrap), and by using an ROV to measure the density of zooplanktonin a small lake. As configured here, this particular ROV wassuitable for measuring the density of the cladocerans Daphniaand Holopedium. It was also suitable for assessing the distribution,but not absolute densities, of Chaoborus and Leptodora. Imagequality was inadequate for quantitative estimates of copepod(Diaptomus minutus) abundance, and prevented us from studyingbehavioral responses of copepods to the vehicle. We concludethat the ROV has at least three useful features: it can be usedto locate patches of those species that are imaged effectively;a large number of samples (videotapes) can be collected almostsynoptically with high spatial resolution; the ROV enables insitu observation of zooplankton. The ROV also has three importantlimitations: the small image volume makes it difficult to studyrare organisms; inadequate image resolution precludes studiesof relatively small organisms (e.g. the calanoid copepod D.minutus);zooplankton respond to the presence of the ROV.     

Two unusual budding bacteria isolated from a swimming pool

S ly , L.I. & H argreaves , M.H. 1984. Two unusual budding bacteria isolated from a swimming pool. Journal of Applied Bacteriology 56 , 479–486.
Two unusual strains of budding bacteria were isolated on a Millipore Pseudomonas Count Water Tester during routine monitoring of Pseudomonas aeruginosa counts in a swimming pool. The first isolate has been identified as Blastobacter sp. It was a yellow-pigmented, Gram negative rod-shaped organism with a polar holdfast by which it attached to solid surfaces or other cells to form rosettes. The cells reproduced by asymmetric division or budding at the free pole of the cell, producing motile daughter cells with a single polar flagellum. The second isolate, which has not yet been identified, was a red-pigmented, Gram negative rod-shaped organism which produced one or more buds at each pole of the cell. Cell division appears to occur by both binary fission and by budding. Both organisms were strict aerobes, catalase and oxidase positive and did not produce acid from glucose in Hugh and Leifson medium.     

The biology and energetics of the potato aphid Macrosiphum euphorbiae, living in galls of the apple aphids Dysaphis devecta and Aphis pomi

A non-gall-forming aphid, Macrosiphum euphorbiae, was reared within the galls of Dysaphis devecta and Aphis pomi which had been induced in apple seedlings. Similar aphids were also reared on ungalled seedling leaves of a similar age and also on mature leaves and in old galls.There is a weak positive linear relationship between lipid content and pre-reproductive adult dry weight, but aphids living on young galled or ungalled plant tissue have 30% lipid compared to 11% for aphids living on old plant tissue. Adult aphids gradually decline in weight, losing between 24% and 38% of their pre-reproductive biomass before death. The energy content of this loss subsidieses reproduction. Reproduction of aphids feeding in old galls or on mature leaves was negligible, but on younger tissues average fecundity was 31, there being little difference between aphids living on galled and ungalled tissue. There is no simple relationship between pre-reproductive adult embryo content and fecundity.The principal factor mediating honeydew production was aphid size and this factor overrides any variation caused by different feeding sites. Honeydew production averaged 0.43 mg during a life of 30 days. Aphids successfully completing their life cycle have a life-time energy consumption of 30.58 joules of which 18% is lost as heat during respiration (R), 30% is contained in honeydew (F+U), 1% is contained in exuviae (Pe). Larval growth accounts for 17% (Pg), and adult reproduction for 34% (Pr).The P/C ratio for M. euphorbiae is 53% and is broadly comparable with aphids living on herbaceous plants.

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Résumé Un puceron ne formant pas de galles, Macrosiphum euphorbiae, a été élevé dans des galles de Dysaphis devecta et Aphis pomi formées sur semis de pommiers. D'autres M. euphorbiae ont été élevés sur feuilles sans galles du même âge provenent de semis identiques, sur feuilles mûres et sur vieilles galles.Il y a une faible relation positive linéaire entre la teneur en lipides et le poids sec des adultes avant la reproduction, mais les pucerons élevés sur tissus végétaux jeunes avec ou sans galles contiennent 30% de lipides contre 11% pour ceux élevés sur tissus âgés. Le poids des pucerons adultes diminue progressivement, la perte avant la mort se situant entre 24 et 38% de la biomasse avant la reproduction. Le contenu énergétique de ces pertes alimente la reproduction. La reproduction de pucerons consommant les vieilles galles ou les feuilles mûres était négligeable, mais sur jeunes tissus la fécondité moyenne était de 31-avec peu de différences entre pucerons sur galles ou feuilles-. Il n'y a pas de corrélation simple entre le contenu en embryon des adultes avant la reproduction et la fécondité.Le principal paramètre conditionnant la production de miellat est la taille du puceron; ce paramètre surpasse toute variation provoquée par les divers lieux d'alimentation. La production moyenne de miellat est de 0,43-mg pendant une vie de 30 jours. Les pucerons accomplissant leur cycle avec succès utilisent pendant leur vie 30,58 joules, dont 18% sont dissipés sous forme de chaleur pendant la respiration (R); le contenu du miellat (F+U) correspond à 30%, et 1% est contenu dans l'exuvie (Pe). La croissance larvaire (Pg) utilise 17%, et l'activité reproductrice des adultes (Pr) 34% de l'énergie. Le rapport P/C-53% pour M. euphorbiae-est globalement comparable à celui des pucerons vivant sur plantes herbacées.

     

The binding of isolated mesophyll cells from barley leaves to hyphae of Pyrenophora teres

Live mesophyll cells from barley leaves were isolated and used to investigate contact phenomena between these cells and hyphae of the barley pathogen Pyrenophora teres. When incubated with colonies of P. teres, the isolated cells became attached to the hyphae. The binding of the cells may have been mediated by an affinity between cellulose in the mesophyll cell wall and extracellular material produced by the fungal hyphae. Different fungi exhibited a wide range of affinities for the mesophyll cells. It is suggested that isolated mesophyll cells may be a useful tool in the study of host-pathogen interfaces.     

Potassium and ventilation during incremental exercise in trained and untrained men.

The present investigation was undertaken to examine the relationship between plasma potassium (K+) and ventilation (VE) during incremental exercise. Blood lactate (La-) was also measured, and its relationship with VE was similarly examined. Eight endurance-trained triathletes (ET) and eight active but untrained men (UT) performed an incremental cycling test to volitional fatigue. Maximal oxygen uptake (VO2max) and oxygen uptake (VO2) at lactate threshold (LT) were higher (P < 0.05) in ET (VO2max 4.60 +/- 0.10 l/min, LT 2.77 +/- 0.85 l/min) than in UT (VO2max 3.79 +/- 0.11 l/min, LT 1.94 +/- 0.60 l/min). There were significant (P < 0.05) correlations between VE and K+ (UT 0.87, ET 0.77) and between VE and La- (UT 0.88, ET 0.85). In ET compared with UT, VE was lower (P < 0.05) at 330 W, K+ was lower at 300 and 330 W, and La- was lower at all work loads > 90 W. These results suggest that K+ may make an important contribution to the regulation of ventilation during incremental exercise and that endurance training attenuates the K+ response to that exercise.     

Uniparental isodisomy of chromosome 2 causing MRPL44-related multisystem mitochondrial disease

Mutations in nuclear-encoded protein subunits of the mitochondrial ribosome are an increasingly recognised cause of oxidative phosphorylation system (OXPHOS) disorders. Among them, mutations in the MRPL44 gene, encoding a structural protein of the large subunit of the mitochondrial ribosome, have been identified in four patients with OXPHOS defects and early-onset hypertrophic cardiomyopathy with or without additional clinical features. A 23-year-old individual with cardiac and skeletal myopathy, neurological involvement, and combined deficiency of OXPHOS complexes in skeletal muscle was clinically and genetically investigated. Analysis of whole-exome sequencing data revealed a homozygous mutation in MRPL44 (c.467 T?>?G), which was not present in the biological father, and a region of homozygosity involving most of chromosome 2, raising the possibility of uniparental disomy. Short-tandem repeat and genome-wide SNP microarray analyses of the family trio confirmed complete maternal uniparental isodisomy of chromosome 2. Mitochondrial ribosome assembly and mitochondrial translation were assessed in patient derived-fibroblasts. These studies confirmed that c.467 T?>?G affects the stability or assembly of the large subunit of the mitochondrial ribosome, leading to impaired mitochondrial protein synthesis and decreased levels of multiple OXPHOS components. This study provides evidence of complete maternal uniparental isodisomy of chromosome 2 in a patient with MRPL44-related disease, and confirms that MRLP44 mutations cause a mitochondrial translation defect that may present as a multisystem disorder with neurological involvement.

     

Hexazonium pararosaniline as a fixative for animal tissues

Hexazonium pararosaniline is a valuable reagent that has been used in enzyme activity histochemistry for 50 years. It is an aqueous solution containing the tris-diazonium ion derived from pararosaniline, an aminotriarylmethane dye, and it contains an excess of nitrous acid that was not consumed in the diazotization reaction. Other investigators have found that immersion for 2 min in an acidic (pH 3.5) 0.0015 M hexazonium pararosaniline solution can protect cryostat sections of unfixed animal tissues from the deleterious effects of aqueous reagents such as buffered solutions used in immunohistochemistry, while preserving specific affinities for antibodies. In the present investigation hexazonium pararosaniline protected lymphoid tissue and striated muscle against the damaging effects of water or saline. The same protection was conferred on unfixed sections treated with dilute nitrous or hydrochloric acid in concentrations similar to those in hexazonium pararosaniline solutions. Model tissues (solutions, gels or films containing gelatin and/or bovine albumin) responded predictably to well known cross-linking (formaldehyde) or coagulant (mercuric chloride) fixatives. Hexazonium pararosaniline solutions prevented the dissolution of protein gels in water only after 9 or more days of contact, during which time considerable swelling occurred. It is concluded that there is no evidence for a “fixative” action of hexazonium pararosaniline. The protective effect on frozen sections of unfixed tissue is attributable probably to the low pH of the solution.     

Engagement with HIV Prevention Treatment and Care among Female Sex Workers in Zimbabwe: a Respondent Driven Sampling Survey

Objective(S)

To determine the HIV prevalence and extent of engagement with HIV prevention and care among a representative sample of Zimbabwean sex workers working in Victoria Falls, Hwange and Mutare.

Design

Respondent driven sampling (RDS) surveys conducted at each site.

Methods

Sex workers were recruited using respondent driven sampling with each respondent limited to recruiting 2 peers. Participants completed an interviewer-administered questionnaire and provided a finger prick blood sample for HIV antibody testing. Statistical analysis took account of sampling method.

Results

870 women were recruited from the three sites. HIV prevalence was between 50 and 70%. Around half of those confirmed HIV positive were aware of their HIV status and of those 50-70% reported being enrolled in HIV care programmes. Overall only 25-35% of those with laboratory-confirmed HIV were accessing antiretroviral therapy. Among those reporting they were HIV negative, 21-28% reported having an HIV test in the last 6 months. Of those tested HIV negative, most (65-82%) were unaware of their status. Around two-thirds of sex workers reported consistent condom use with their clients. As in other settings, sex workers reported high rates of gender based violence and police harassment.

Conclusions

This survey suggests that prevalence of HIV is high among sex workers in Zimbabwe and that their engagement with prevention, treatment and care is sub-optimal. Intensifying prevention and care interventions for sex workers has the potential to markedly reduce HIV and social risks for sex workers, their clients and the general population in Zimbabwe and elsewhere in the region.