Mi Casa es Su Casa: how an intracellular symbiont manipulates host biology

Wolbachia pipientis, the most common intracellular infection on the planet, infects 40% of insects as well as nematodes, isopods and arachnids. Wolbachia are obligately intracellular and challenging to study; there are no genetic tools for manipulating Wolbachia nor can they be cultured outside of host cells. Despite these roadblocks, the research community has defined a set of Wolbachia loci involved in host interaction: Wolbachia effectors. Through the use of Drosophila genetics, surrogate systems and biochemistry, the field has begun to define the toolkit Wolbachia use for host manipulation. Below we review recent findings identifying these Wolbachia effectors and point to potential, as yet uncharacterized, links between known phenotypes induced by Wolbachia infection and predicted effectors.     

Alveolar expansion imaged by optical sectioning microscopy.

During lung expansion, the pattern of alveolar perimeter distension is likely to be an important determinant of lung functions as, for example, surfactant secretion. However, the segmental characteristics of alveolar perimeter distension remain unknown. Here, we applied real-time confocal microscopy in the isolated, perfused rat lung to determine the micromechanics of alveolar perimeter distension. To image the alveolar perimeter, we loaded alveolar epithelial cells with a fluorescent dye that we microinjected into the alveolus. Then we viewed single alveoli in a 2-microm-thick optical section at a focal plane 20 mum deep to the pleural surface at baseline. In each alveolus, we identified five to eight segments of the perimeter. For each segment, we determined length (L(seg)) by means of image analysis. At baseline alveolar pressure (P(alv)) of 5 cmH(2)O, L(seg) averaged 46 microm. We hyperinflated the lung to P(alv) of 20 cmH(2)O and identified the same optical section as referenced against morphological landmarks. Hyperinflation increased mean L(seg) by 14%. However, segment distension was heterogeneous, even within the single alveolus. Furthermore, distension was greater in alveolar type 1 than type 2 epithelial cells. These findings indicate that alveoli expand nonuniformly, suggesting that segments that distend the most might be preferred alveolar locations for injury in conditions associated with lung overdistension.     

Length–weight relationships of three freshwater fish species from Rupnaryan and Kangsabati River,West Bengal,India

The length–weight relationships (LWRs) of three freshwater fish species from the Kangsabati and Rupnaryan river in West Bengal, India are presented, namely as Amblypharyngodon microlepis (Bleeker, 1853), Parambassis lala (Hamilton, 1822) and Macrognathus aculeatus (Bloch, 1786). Gill‐nets (mesh sizes with 0.5 cm–4 cm), cast‐nets (up to 1 × 1 cm mesh size with up to 4.0 m² area) and scoop‐nets (0.3 × 0.3 cm and 0.5 × 0.5 cm mesh size) were used from January, 2017 to April, 2018. Sampling was done every 15 days during this period. The value of parameter “b” ranged from 2.751 to 2.895 with highly significant correlations (r² > 0.95).     

High frequency in vitro propagation of Phyllanthus amarus Schum. & Thom. by shoot tip culture

With the aim of micropropagation of Phyllanthus amarus, an important medicinal herb, shoot tips were cultured in Murashige and Skoog's medium supplemented with kinetin/ BAP singly or in combination with IAA. Growth regulators at lower range (0.1-1.0 mg L(-1)) stimulated direct regeneration of shoots. Kinetin was superior to BAP and kinetin-IAA combination was more suitable than kinetin alone. About 15 shoots were yielded per explant after 30 days of culture in the medium containing kinetin and IAA both at 0.1mg L(-1). The cluster of proliferated shoots elongated and rooted simultaneously under the same treatment following another subculture, thus shortening the total time schedule of micropropagation. Shoot tips of regenerated shoots were continuously used to regenerate new shoots with periodic transfer to fresh medium resulting in a steady supply of normal, healthy plants without any deviation in the production rate during a continuous one year culture. Micropropagated plants were successfully established in soil with high survivality (80%).     

Signal transduction events in mammalian cells in response to ionizing radiation

Ionizing radiations elicit a variety of biological effects in mammalian cells. In recent years altered signal transduction has been recognized as a key cellular response to ionizing radiation. Several oncogenes, the products of which are components of signal transduction pathways and which are over-expressed in many tumors, are specifically induced in cells exposed to radiation. It has also become evident that the oncogene ras and the serine/threonine protein kinase oncogenes raf and PKC confer radio-resistance to tumor cells. Modulation of these genes or their activity by natural compounds may offer a strategy to treat cancer by enhancing radiation-induced apoptosis of tumor cells.     

Antidepressant activity of hyperforin conjugates of the St. John's wort,Hypericum perforatum Linn.: an experimental study

Nine extracts of H. perforatum, containing hyperforin in conjugated forms, but devoid of free hyperforin and adhyperforin, were subjected to antidepressant screening using the forced swim test (FST). The observed activity was compared with that of SJW extracts containing hyperforin and adhyperforin (in free form). Results indicate that hyperforin conjugates exhibit significant antidepressant activity as evidenced by the reduced immobility period in the FST in rats.     

Ribosomal DNA phylogeny of the Bangiophycidae (Rhodophyta) and the origin of secondary plastids

We sequenced the nuclear small subunit ribosomal DNA coding region from 20 members of the Bangiophycidae and from two members of the Florideophycidae to gain insights into red algal evolution. A combined alignment of nuclear and plastid small subunit rDNA and a data set of Rubisco protein sequences were also studied to complement the understanding of bangiophyte phylogeny and to address red algal secondary symbiosis. Our results are consistent with a monophyletic origin of the Florideophycidae, which form a sister-group to the Bangiales. Bangiales monophyly is strongly supported, although Porphyra is polyphyletic within Bangia. Bangiophycidae orders such as the Porphyridiales are distributed over three independent red algal lineages. The Compsopogonales sensu stricto, consisting of two freshwater families, Compsopogonaceae and Boldiaceae, forms a well-supported monophyletic grouping. The single taxon within the Rhodochaetales, Rhodochaete parvula, is positioned within a cluster containing members of the Erythropeltidales. Analyses of Rubisco sequences show that the plastids of the heterokonts are most closely related to members of the Cyanidiales and are not directly related to cryptophyte and haptophyte plastid genomes. Our results support the independent origins of these secondary algal plastids from different members of the Bangiophycidae.     

Alpha-B crystallin gene (CRYAB) mutation causes dominant congenital posterior polar cataract in humans

Congenital cataracts are an important cause of bilateral visual impairment in infants. In a four-generation family of English descent, we mapped dominant congenital posterior polar cataract to chromosome 11q22-q22.3. The maximum LOD score, 3.92 at recombination fraction 0, was obtained for marker D11S898, near the gene that encodes crystallin alpha-B protein (CRYAB). By sequencing the coding regions of CRYAB, we found in exon 3 a deletion mutation, 450delA, that is associated with cataract in this family. The mutation resulted in a frameshift in codon 150 and produced an aberrant protein consisting of 184 residues. This is the first report of a mutation, in this gene, resulting in isolated congenital cataract.     

Identification and functional consequences of a new mutation (E155G) in the gene for GCAP1 that causes autosomal dominant cone dystrophy

Mutations in the gene for guanylate cyclase-activating protein-1 (GCAP1) (GUCA1A) have been associated with autosomal dominant cone dystrophy (COD3). In the present study, a severe disease phenotype in a large white family was initially shown to map to chromosome 6p21.1, the location of GUCA1A. Subsequent single-stranded conformation polymorphism analysis and direct sequencing revealed an A464G transition, causing an E155G substitution within the EF4 domain of GCAP1. Modeling of the protein structure shows that the mutation eliminates a bidentate amino acid side chain essential for Ca2+ binding. This represents the first disease-associated mutation in GCAP1, or any neuron-specific calcium-binding protein within an EF-hand domain, that directly coordinates Ca2+. The functional consequences of this substitution were investigated in an in vitro assay of retinal guanylate cyclase activation. The mutant protein activates the cyclase at low Ca2+ concentrations but fails to inactivate at high Ca2+ concentrations. The overall effect of this would be the constitutive activation of guanylate cyclase in photoreceptors, even at the high Ca2+ concentrations of the dark-adapted state, which may explain the dominant disease phenotype.