Differences between tuberculosis cases infected with Mycobacterium africanum, West African type 2, relative to Euro-American Mycobacterium tuberculosis: an update

Mycobacterium africanum (MAF) is a common cause of human pulmonary tuberculosis in West Africa. We previously described phenotypic differences between MAF and Mycobacterium tuberculosis (MTB) among 290 patients. In the present analysis, we compared 692 tuberculosis patients infected with the two most common lineages within the (MTB) complex found in the Gambia, namely MAF West African type 2 (39% prevalence) and Euro-American MTB (55% prevalence). We identified additional phenotypic differences between infections with these two organisms. MAF patients were more likely to be older and HIV infected. In addition, they had worse disease on chest X-ray, despite complaining of cough for an equal duration, and were more likely severely malnourished. In this cohort, the prevalence of MAF did not change significantly over a 7-year period.     

Extraocular vision in the sea urchin Diadema setosum

In most organisms, specific structures are responsible for detecting light patterns and vision. Several species of sea urchins appear to have a diffuse photoreceptor system that enables them to detect light and in some cases objects. The presence of extraocular vision was investigated on a sea urchin common in northern Oman, Diadema setosum. Urchins from 8- to 10-m deep coral communities were used in controlled experiments that quantified the orientation response of the urchins to various visual cues: size, contrast and colour of circular targets simulating urchins’ outlines. Urchins responded to black discs down to 11° initial visual angle but not to smaller discs. The minimum grey-scale value triggering a response was between 50 and 37% black. Urchins responded to red targets but not to green or blue ones. An average angular distance between spines of 5.3° suggested a visual acuity of about 10.6°. D. setosum thus showed extraocular vision allowing them to detect objects of different sizes, contrasts and to some extent colour, supporting the hypothesis that the whole sea urchin’s body acts as a single large compound eye.     

Interaction of Trastuzumab with biomembrane models at air-water interfaces mimicking cancer cell surfaces

Trastuzumab (Tmab) is a monoclonal antibody administered as targeted therapy for HER2-positive breast cancer whose molecular interactions at the HER2 receptor microenvironment are not completely clarified yet. This paper describes the influence of Tmab in the molecular organization of films of biological-relevant molecules at the air water interface. For that, we spread components of tumorigenic and non-tumorigenic cells directly on the air-water interface. The physicochemical properties of the films were investigated with surface pressure-area isotherms and Brewster angle microscopy, and distinction between the cellular lines with higher or lower amount of HER2 could be detected based on the physicochemical properties of the interfacial films. The systems organized at the air-water interface were transferred to solid supports as Langmuir-Blodgett films and the nano-scale morphology investigated with atomic force microscopy. The overall results related to Tmab interacting with the films lead to the conclusion that Tmab tends to condense rich-HER2 films, causing irregular dimerization of the receptor protein, changing the membrane topography of the films, with formation of phases with different levels of reflectivity and aggregation morphology, and finally revealing that the interaction of the antibody with proteo-lipidic biointerfaces is modulated by the film composition. We believe that novel perspectives concerning the molecular interactions in the plasma membrane microenvironment through Langmuir monolayers can be obtained from this work in order to enhance the Tmab-based cancer therapy.     

Entodiniomorph Ciliates from the Stomach of Hippopotamus amphibius, with Descriptions of Two New Genera and Three New Species

Entodiniomorph ciliates, belonging to the family Cycloposthiidae, are described from the stomach contents of Hippopotamus amphibius. Monoposthium acanthum gen. n., sp. n., with typical cycloposthiid structure, differs from other genera in having only 1 caudalium. Parentodinium gen. n., represented by P. africanum sp. n. and P. ostrea sp. n., although superficially resembling Entodinium, is considered to be a relatively unspecialized cycloposthiid.     

New PCR based markers allowed to identify <Emphasis Type="Italic">Secale</Emphasis> chromatin in wheat-<Emphasis Type="Italic">Secale africanum</Emphasis> introgression lines

The genus of Secale has many agronomically important characters. In order to use the best of this species, markers tracking the rye chromatin incorporated into wheat must be developed. In this study, one rye genome-specific random amplified polymorphic DNA (RAPD) marker was isolated from Secale africanum (R^a genome). Two cloned markers, named OPP13₁₁₆₅ and OPP13₆₆₂, were 1165 bp and 662 bp, respectively. Sequence analysis revealed that OPP13₁₁₆₅ was highly homologous to a part of a new class of transposon-like gene called the Revolver family, and OPP13₆₆₂ was partially similar to LTR gypsy-like retrotransposon. Fluorescence in situ hybridization (FISH) showed only OPP13₁₁₆₅ localized within the whole arms of rye except their terminal regions and no signal was detected on wheat chromosomes, while OPP13₆₆₂ had no hybridization signal detected on wheat and rye genomes. Based on these sequences, two pairs of sequence-characterized amplified region (SCAR) primers were designed, and the resulted SCAR markers were able to target both cultivated and wild Secale species. The FISH patterns and the two SCAR markers should be able to identify and track all wheat-rye translocation lines, especially the S. africanum chromatin.     

Patterns of nocturnal movement of the long-spined sea urchin<Emphasis Type="Italic"> Diadema antillarum</Emphasis> (Philippi) in Gran Canaria (the Canary Islands,central East Atlantic Ocean)

We tagged individuals of the sea urchin Diadema antillarum (Philippi) around the island of Gran Canaria (The Canary Islands) during winter 2001–2002 using a new technique, consisting of the insertion of a hook fastened to a fishing line into the aboral pole (periproctal membrane). This allowed individual identification of tagged sea urchins. The goals were: (1) to quantify nocturnal movements and the homing behaviour of this echinoid on shallow rocky bottoms, and (2) to assess short term spatial and temporal variability of these movements. Tagged sea urchins displayed clear homing behaviour. The mean distance travelled at night was 3.7±1.2 m (range 1.0–5.1 m). Mean speed of nocturnal movement was 33±26 cm h^–1 (range 5–110 cm h^–1). We observed greater movement at midnight than at the beginning and the end of the night.Communicated by H.-D. Franke     

Uncommon southwest swells trigger sea urchin disease outbreaks in Eastern Atlantic archipelagos

Recurrent sea urchin mass mortality has recently affected eastern Atlantic populations of the barren‐forming sea urchin Diadema africanum. This new episode of die‐off affords the opportunity to determine common meteorological and oceanographic conditions that may promote disease outbreaks. The population dynamics of this sea urchin species are well known—urchin barrens have persisted for many decades along most of the coastlines off the archipelagos of Madeira, Selvages, and the Canary Islands, where they limit macroalgae biomass growth. However, this new and explosive mortality event decimated the sea urchin population by 93% on Tenerife and La Palma Islands. Two severe episodes of southwestern rough sea that led to winter storms, in February 2010 (Xynthia) and February 2018 (Emma), preceded both mass mortality events. The autumn and winter months of those years were anomalous and characterized by swells with an average wave height above 2 m that hit the south and southwest sides of the islands. The amoeba Paramoeba brachiphila was the only pathogen isolated this time from the moribund and dead sea urchins, suggesting that the amoeba was the primary cause of the mortality. This new sea urchin die‐off event supports the “killer‐storm” hypothesis that has been already described for western Atlantic coasts. These anomalous southwest storms during winters generate pronounced underwater sediment movement and large‐scale vertical mixing, detected in local tide gauge, which may promote paramoebiasis. This study presents valuable insights about climate‐mediated changes in disease frequency and its impacts on the future of coastal marine ecosystems in the Atlantic.     

Postmetamorphic Growth and Metabolism of Long-Spined Black Sea Urchin (Diadema antillarum) Reared in the Laboratory

Postmetamorphic growth and metabolism measurements were obtained on two cohorts of laboratory-reared Diadema antillarum. The cohorts grew linearly from less than 1 mm to over 43 mm. Daily growth averaged 0.097 and 0.11 mm d^-1, respectively, for the two cohorts, and was found to differ significantly. Urchin metabolism was examined by a series of simultaneous measurements of oxygen consumption and ammonium excretion over 16 days on starved juveniles ranging 16.5 to 18.3 mm. Metabolic activity under conditions of starvation was used as a test of the viability of urchins reared in the laboratory with cultured food resources. Catabolic activity differed from the first week of starvation compared to the second. Metabolic response included: (1) a 2.2-fold increase in oxygen consumption rate; (2) 50% decline in ammonium excretion rate; and (3) a 5.1-fold increase in oxygen to nitrogen ratio. These measurements are consistent with a shift from almost pure protein catabolism during the first seven days of starvation to a lipid : protein catabolic ratio of 1 : 1 after the first week. Growth and metabolism experiments of this type are seen as a first step towards optimizing laboratory culture techniques of this species.     

Local and regional scale recovery of Diadema promotes recruitment of scleractinian corals

The phase change from coral to macroalgal dominance on many Caribbean reefs was exacerbated by the mortality of the echinoid Diadema antillarum in 1983–1984, and until recently, this sea urchin has remained rare on reefs throughout the western Atlantic. By the late 1990s, Diadema started to reappear in large numbers on some Jamaican reefs, and by 2000, the high densities were correlated with significantly greater abundances of juvenile corals. Here, we show that dense populations of Diadema now occur over a multi-kilometre-wide scale at six locations scattered along a 4100 km arc across the entire Caribbean. In all cases, these dense populations are found in shallow water (< 6 m depth) on outer reef communities and are associated with reduced macroalgal cover and enhanced coral recruitment. We conclude that population recovery of Diadema is occurring at both local and regional scales, and that grazing by this echinoid is creating conditions favouring the recruitment of corals.     

Phylogeography of the Afromontane Prunus africana reveals a former migration corridor between East and West African highlands

Scattered populations of the same tree species in montane forests through Africa have led to speculations on the origins of distributions. Here, we inferred the colonization history of the Afromontane tree Prunus africana using seven chloroplast DNA loci to study 582 individuals from 32 populations sampled in a range-wide survey from across Africa, revealing 22 haplotypes. The predominant haplotype, HT1a, occurred in 13 populations of eastern and southern Africa, while a second common haplotype, HT1m, occurred in populations of western Uganda and western Africa. The high differentiation observed between populations in East Africa was unexpected, with stands in western Uganda belonging with the western African lineage. High genetic differentiation among populations revealed using ordered alleles (N(ST) = 0.840) compared with unordered alleles (G(ST) = 0.735), indicated a clear phylogeographic pattern. Bayesian coalescence modelling suggested that 'east' and 'west' African types likely split early during southward migration of the species, while further more recent splitting events occurred among populations in the East of the continent. The high genetic similarity found between western Uganda and west African populations indicates that a former Afromontane migration corridor may have existed through Equatorial Africa.