Rhabdospora thelohani Laguessé, 1895 (Apicomplexa): new host and geographic records with taxonomic considerations.

New fish species and geographic records for Rhabdospora thelohani Laguessé, 1895 (rodlet cells) are presented. Additionally, the ultrastructure of R. thelohani in Alburnoides bipunctatus ohridanus Karaman, Borostomias antarcticus (L?nnberg), Leuciscus cephalus albus Bonaparte and Rutilus rubilio (Bonaparte) is compared with that reported by other authors and with members of Subphylum Apicomplexa. The ultrastructure of R. thelohani was similar in all the fish species examined; however, the organism was not present in all members of any single species and had intertissue density variations. Rhabdospora thelohani is pyriform, averaging in size 7 X 12 micrometer, with a basal nucleus. The surface complex is composed of a layer (0.5 micrometer diameter) formed by microfilaments (9.3 nm) and an outer trilaminar membrane (9.3 nm). The cytoplasm contains structures identical to rhoptries, micronemes and subpellicular microtubules. Mitochondria, Golgi apparatus, and rough endoplasmic reticulum were not observed, althouth free ribosomes were present and arranged in a vesicular pattern. The observations suggest that the organism moves between cell of epithelial layers and is either released into a lumen intact or passively or actively discharges its contents into a lumen. Results from this study indicate that R. thelohani should be considered a member of Apicomplexa unless definitive evidence is presented to the contrary.     

Indoor residual spraying for the control of visceral leishmaniasis: A systematic review

Indoor Residual Spraying (IRS) is one of the interventions to control the vectors of Visceral Leishmaniasis (VL). Different insecticides are used in affected countries, also in the Regional Initiative for the Elimination of VL in South-East Asia. This systematic review assesses all available studies analysing the effectiveness of IRS on the key vectors of VL. The systematic review followed PRISMA guidelines, with a broad search strategy, applied to seven key databases. Inclusion criteria were studies focusing on 1) Visceral leishmaniasis 2) Indoor Residual Spraying (IRS) or synonyms, and 3) all primary research methods. 21 studies were included, five cluster randomised controlled trials (cRCTs), one randomised controlled trial (RCT), 11 intervention studies, also included were three modelling studies and one survey. 19 out of 21 included studies were published between 2009 and 2020. 18 of the studies were conducted in the context of the Regional Initiative. Effects of IRS on vector populations are positive, confirmed in terms of effectiveness and by the availability of studies. Deltamethrin and alpha-Cypermethrin reduce total sandfly counts, and/or Phlebotomus argentipes counts by up to 95% with an effect of a minimum of one month. Prolonged effects are not regularly seen. DDT has been used in India only: whereas in the 1990s a good effect could be measured, this effect waned over time. Two intervention studies, embedded in larger programmes in 2019 and 2020, replaced DDT with alpha-Cypermethrin throughout the study. Combinations of different interventions are not systematically researched, however showing some promising results, for example for the combination of IRS and Temephos. Constant monitoring of insecticide resistancies and quality delivery of IRS are confirmed as key issues for programmes. No human transmission data are available to directly relate an effect of IRS–although modelling studies confirm the effect of IRS on human transmission. Concluding, IRS continues to be an effective intervention for Phlebotomus argentipes control. Delivery requires constant monitoring and quality assurance. Further studies need to assess IRS in different geographical areas affected by VL and combinations of interventions.     

Two closely linked tomato HKT coding genes are positional candidates for the major tomato QTL involved in Na+/K+ homeostasis

The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na⁺] and [K⁺] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na⁺‐selective class I‐HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single‐nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from HKT1;1 and HKT1;2. Their expression patterns and phenotypic effects were further investigated in two near‐isogenic lines (NILs): 157‐14 (double homozygote for the cheesmaniae alleles) and 157‐17 (double homozygote for the lycopersicum alleles). The expression pattern for the HKT1;1 and HKT1;2 alleles was complex, possibly because of differences in their promoter sequences. High salinity had very little effect on root dry and fresh weight and consequently on the plant dry weight of NIL 157‐14 in comparison with 157‐17. A significant difference between NILs was also found for [K⁺] and the [Na⁺]/[K⁺] ratio in leaf and stem but not for [Na⁺] arising a disagreement with the corresponding RIL population. Their association with leaf [Na⁺] and salt tolerance in tomato is also discussed.     

Length weight relationships of five marine fishes from the Bay of Bengal

Length weight relationships (LWR) of five marine fishes were estimated from the Bay of Bengal, Bangladesh. Fish samples were collected occasionally from fisher's catch with gill net (mesh size: 3 cm) during November 2019 to October 2020. Fishing was done overnight. Total length (0.1 cm) and body weight (0.01 g) of each individual were measured. We recorded maximum total length for P. maculatus (55.0 cm) and P. parmatus (39.0 cm).     

Molecular Phylogeny and Barcoding of Caulerpa (Bryopsidales) Based on the tufA,rbcL, 18S rDNA and ITS rDNA Genes

The biodiversity assessment of different taxa of the genus Caulerpa is of interest from the context of morphological plasticity, invasive potential of some species and biotechnological and pharmacological applications. The present study investigated the identification and molecular phylogeny of different species of Caulerpa occurring along the Indian coast inferred from tufA, rbcL, 18S rDNA and ITS rDNA nucleotide sequences. Molecular data confirmed the identification of 10 distinct Caulerpa species: C. veravalensis, C. verticillata, C. racemosa, C. microphysa, C. taxifolia, C. sertularioides, C. scalpelliformis, C. serrulata, C. peltata and C. mexicana. All datasets significantly supported the sister relationship between C. veravalensis and C. racemosa var. cylindracea. It was also concluded from the results that the specimen identified previously as C. microphysa and C. lentillifera could not be considered as separate species. The molecular data revealed the presence of multiple lineages for C. racemosa which can be resolved into separate species. All four markers were used to ascertain their utility for DNA barcoding. The tufA gene proved a better marker with monophyletic association as the main criteria for identification at the species level. The results also support the use of 18S rDNA insertion sequences to delineate the Caulerpa species through character-based barcoding. The ITS rDNA (5.8S-ITS2) phylogenetic analysis also served as another supporting tool. Further, more sequences from additional Caulerpa specimens will need to be analysed in order to support the role of these two markers (ITS rDNA and 18S insertion sequence) in identification of Caulerpa species. The present study revealed the phylogeny of Caulerpa as complete as possible using the currently available data, which is the first comprehensive report illustrating the molecular phylogeny and barcoding of the genus Caulerpa from Indian waters.     

Modulating the Intrinsic Disorder in the Cytoplasmic Domain Alters the Biological Activity of the N-Methyl-d-aspartate-sensitive Glutamate Receptor

The NMDA-sensitive glutamate receptor is a ligand-gated ion channel that mediates excitatory synaptic transmission in the nervous system. Extracellular zinc allosterically regulates the NMDA receptor by binding to the extracellular N-terminal domain, which inhibits channel gating. Phosphorylation of the intrinsically disordered intracellular C-terminal domain alleviates inhibition by extracellular zinc. The mechanism for this functional effect is largely unknown. Proline is a hallmark of intrinsic disorder, so we used proline mutagenesis to modulate disorder in the cytoplasmic domain. Proline depletion selectively uncoupled zinc inhibition with little effect on receptor biogenesis, surface trafficking, or ligand-activated gating. Proline depletion also reduced the affinity for a PDZ domain involved in synaptic trafficking and affected small molecule binding. To understand the origin of these phenomena, we used single molecule fluorescence and ensemble biophysical methods to characterize the structural effects of proline mutagenesis. Proline depletion did not eliminate intrinsic disorder, but the underlying conformational dynamics were changed. Thus, we altered the form of intrinsic disorder, which appears sufficient to affect the biological activity. These findings suggest that conformational dynamics within the intrinsically disordered cytoplasmic domain are important for the allosteric regulation of NMDA receptor gating.     

Nicotinic acetylcholine receptors (nAChRs) at zebrafish red and white muscle show different properties during development

Nicotinic acetylcholine receptors (nAChRs) are highly expressed at the vertebrate neuromuscular junction (NMJ) where they are required for muscle activation. Understanding the factors that underlie NMJ development is critical for a full understanding of muscle function. In this study we performed whole cell and outside‐out patch clamp recordings, and single‐cell RT‐qPCR from zebrafish red and white muscle to examine the properties of nAChRs during the first 5 days of development. In red fibers miniature endplate currents (mEPCs) exhibit single exponential time courses at 1.5 days postfertilization (dpf) and double exponential time courses from 2 dpf onwards. In white fibers, mEPCs decay relatively slowly, with a single exponential component at 1.5 dpf. By 2 and 3 dpf, mEPC kinetics speed up, and decay with a double exponential component, and by 4 dpf the exponential decay reverts back to a single component. Single channel recordings confirm the presence of two main conductance classes of nAChRs (～45 pS and ～65 pS) in red fibers with multiple time courses. Two main conductance classes are also present in white fibers (～55 pS and ～73 pS), but they exhibit shorter mean open times by 5 dpf compared with red muscle. RT‐qPCR of mRNA for nicotinic receptor subunits supports a switch from γ to ε subunits in white fibers but not in red. Our findings provide a developmental profile of mEPC properties from red and white fibers in embryonic and larval zebrafish, and reveal previously unknown differences between the NMJs of these muscle fibers.© 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 916–936, 2016