Studies on anther cultures of tomato —Lycopersicon esculentum Mill

The anthers of three genotypes ofLycopersicon esculentum, viz. cv. HS-101, cv. HS-102 and an F₁ hybrid (Montfavet 63-4xHS-101) in different stages of development were cultured in various defined nutritive media. Only anthers containing microspores in the early uninucleate stage were found to respond with the culture medium in the formation of androgenic callus. The DGII medium with 2 mg l⁻¹ NAA and 1 mg 1⁻¹ kinetin was found to be best for callus induction but MS medium supplemented with 2 mg l⁻¹ 2,4-D and 0.1 mg 1⁻¹ BAP favoured proliferation and growth of the callus. The androgenic microspores followed the ‘B’ type pathway of androgenesis in the formation of callus. Induction of tracheids in the callus could be achieved by supplementing the basal medium with NAA and kinetin or 2,4-D and BAP. Initiation of vessel elements and cambium were favoured by addition of NAA and kinetin and that of the phloem in the presence of 2,4-D and BAP in the basal medium, suggesting that the hormonal requirements for production of different elements of the vascular system in androgenic callus are different. Although roots could be induced from the callus, shoot differentiation could not be achieved under cultural conditions.     

α-Synuclein Levels in Blood Plasma from LRRK2 Mutation Carriers

The diagnosis of Parkinson’s disease (PD) remains primarily a clinical issue, based mainly on phenotypic patterns. The identification of biomarkers capable of permitting the preclinical detection of PD is critically needed. α-Synuclein is a key protein in PD, with missense and multiplication mutations in the gene encoding α-synuclein (SNCA) having been reported in familial cases of PD, and accumulation of the protein identified in Lewy bodies (LBs) and Lewy neurites (LNs) in affected brain regions. With the objective of validating the use of α-synuclein as a clinical or progressive biomarker in an accessible tissue, we used an enzyme-linked immunosorbent assay (ELISA) to measure α-synuclein levels in the peripheral blood plasma of idiopathic PD and LRRK2 mutation carrier patients and compared our findings with healthy control subjects. Compared to healthy controls, we found a significant decrease in plasma total α-synuclein levels in idiopathic PD (iPD) patients (n = 134, p = 0.010). However, the reduction was less significant in patients who were LRRK2 mutation carriers (n = 32, p = 0.133). This lack of significance could be due to the small number of individuals employed in this group. No predictive value of total α-synuclein in the diagnosis of PD was found in a receiver operating characteristic (ROC) curve analysis. Although this is a pilot study requiring corroboration on a larger cohort of patients, our results highlight the possible use of plasma α-synuclein as a biomarker for PD.     

Views on antioxidant mouthwashes as adjunct in periodontal therapy

Clinical decision is often difficult with chlorhexidine mouthwash. The use of antioxidant mouthwashes for the treatment of periodontal disease is in practise. Therefore, it is of interest to collect gleaned information on Antioxidant mouthwashes as periodontal therapy from known literature. Improvement in treatment using antioxidant mouthwashes is reported in several studies. The mouthwash with antioxidants has similar anti-gingivitis, antiplaque and antimicrobial effects as that of chlorhexidine mouthwash.     

Nitrogen fixing bacterial diversity in a tropical estuarine sediments

Microorganisms play a significant role in biogeochemical cycles, especially in the benthic and pelagic ecosystems. Role of environmental parameters in regulating the diversity, distribution and physiology of these microorganisms in tropical marine environment is not well understood. In this study, we have identified dinitrogen (N₂) fixing bacterial communities in the sediments by constructing clone libraries of nitrogenase (nifH) gene from four different stations in the Cochin estuary, along the southeastern Arabian Sea. N₂ fixing bacterial clones revealed that over 20 putative diazotrophs belong to alpha-, beta-, gamma-, delta- and epsilon- proteobacteria and firmicutes. Predominant genera among these were Bradyrhizobium sp. (α-proteobacteria), Dechloromonas sp. (β-proteobacteria); Azotobactor sp., Teredinibacter sp., Methylobacter sp., Rheinheimera sp. and Marinobacterium sp. (γ-proteobacteria); Desulfobacter sp., Desulfobulbus sp. and Desulfovibrio sp. (δ -proteobacteria); Arcobacter sp. and Sulfurospirillum sp. (ε-proteobacteria). Nostoc sp. was solely identified among the cyanobacterial phylotype. Nitrogen fixing Sulfate reducing bacteria (SRBs) such as Desulfobulbus sp., Desulfovibrio sp., Desulfuromonas sp., Desulfosporosinus sp., Desulfobacter sp., were also observed in the study. Most of the bacterial nifH sequences revealed that the identities of N₂ fixing bacteria were less than 95% similar to that available in the GenBank database, which suggested that the sequences were of novel N₂ fixing microorganisms. Shannon-Weiner diversity index of nifH gene ranged from 2.95 to 3.61, indicating an inflated diversity of N₂ fixing bacteria. Canonical correspondence analysis (CCA) implied positive correlation among nifH diversity, N₂ fixation rate and other environmental variables.     

Increased release of serotonin from rat ileum due to dexfenfluramine

Plasma levels of serotonin are elevated in primary pulmonary hypertension even after bilateral lung transplantation, suggesting a possible etiologic role. Serotonin is released primarily from the small intestine. Anorectic agents, such as dexfenfluramine, which can cause pulmonary hypertension, are known to inhibit potassium channels in vascular smooth muscle cells. We examined the hypothesis that dexfenfluramine may stimulate release of serotonin from the ileum by inhibition of K+ channels. In an isolated loop of rat ileum perfused with a physiological salt solution, the administration of dexfenfluramine, its major metabolite D-norfenfluramine, the potassium channel blocker 4-aminopyridine (5 mM), and caffeine (30 mM) increased serotonin levels in the venous effluent. Potassium chloride (60 mM) tended to increase serotonin levels. In genetically susceptible individuals, dexfenfluramine may induce pulmonary hypertension by increasing cytosolic calcium in enterochromaffin cells of the small intestine, thus releasing serotonin and causing vasoconstriction. This work indicates that dexfenfluramine and its major metabolite d-norfenfluramine can increase serotonin release from the small intestine.     

Inflammatory Stress Increases Hepatic CD36 Translational Efficiency via Activation of the mTOR Signalling Pathway

Inflammatory stress is an independent risk factor for the development of non-alcoholic fatty liver disease (NAFLD). Although CD36 is known to facilitate long-chain fatty acid uptake and contributes to NAFLD progression, the mechanisms that link inflammatory stress to hepatic CD36 expression and steatosis remain unclear. As the mammalian target of rapamycin (mTOR) signalling pathway is involved in CD36 translational activation, this study was undertaken to investigate whether inflammatory stress enhances hepatic CD36 expression via mTOR signalling pathway and the underlying mechanisms. To induce inflammatory stress, we used tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) stimulation of the human hepatoblastoma HepG2 cells in vitro and casein injection in C57BL/6J mice in vivo. The data showed that inflammatory stress increased hepatic CD36 protein levels but had no effect on mRNA expression. A protein degradation assay revealed that CD36 protein stability was not different between HepG2 cells treated with or without TNF-α or IL-6. A polysomal analysis indicated that CD36 translational efficiency was significantly increased by inflammatory stress. Additionally, inflammatory stress enhanced the phosphorylation of mTOR and its downstream translational regulators including p70S6K, 4E-BP1 and eIF4E. Rapamycin, an mTOR-specific inhibitor, reduced the phosphorylation of mTOR signalling pathway and decreased the CD36 translational efficiency and protein level even under inflammatory stress resulting in the alleviation of inflammatory stress-induced hepatic lipid accumulation. This study demonstrates that the activation of the mTOR signalling pathway increases hepatic CD36 translational efficiency, resulting in increased CD36 protein expression under inflammatory stress.     

Use of 5´-anchored primers for the enhanced recovery of specific microsatellite markers in Brassica napus L.

Microsatellite markers have assumed great significance in biological research. The isolation and characterisation of microsatellites involves DNA library construction and screening, DNA sequencing, primer design and PCR optimisation. When a microsatellite is situated close to the beginning or end of a cloned fragment, specific primers cannot be designed for one of the flanking sequences, thus hindering the utilisation of such microsatellites as markers. The present approach was to use one 5′-anchored primer complementary to the microsatellite sequence in combination with one specific Cy5- labelled primer with a view to retrieving useful microsatellites, which would otherwise be lost. Six pairs of a 5′ anchored primer and a specific primer were used across a set of 31 Brassica napus winter cultivars and one accession each of five additional Brassica species. Using laser fluorometry a single labelled product was observed after amplification with each of four primer pairs, and one primer pair gave two labelled products. Three products corresponded in size with the products expected if 5′ anchoring was effective, indicating the amplification of locus-specific full-length products including all of the microsatellite repeats. All six primer pairs showed polymorphisms across the Brassica species examined, but only one primer pair showed polymorphisms within B. napus, making it useful for genetic analysis in rapeseed cultivars. The other primer pairs could be useful in studying gene introgression into B. napus or for investigating interspecific crosses involving different Brassica species. Received: 5 August 1999 / Accepted: 1 November 1999     

The fine structure of the endogenous stages of Eimeria labbeana: 2. Mature macrogamonts and young oocysts.

The fine structure of the mature macrogamonts and intracellular oocysts of Eimeria labbeana from the ileal mucosa of experimentally infected Pigeons (Columbia livia) was investigated and described. The macrogamont reached a maximum size of 12.0 x 9.5 mum (average equals 10.8 x 8.8 mum), and was located within a narrow parasitophorus vacuole. Most of the macrogamonts were limited by two membranes. Intravacuolar tubules, 1.2 mum long and 58 nm in diameter, established direct connections between the parasite and the host cell. Each tabule was composed of 9 subunits arranged around the central lumen. Cytoplasmic canaliculi were composed of bundles of microtubule-like structures (8-10 nm wide). Type 1 wall-forming bodies reached a maximum size of 1.8 x 1.5 mum, and many had centric or eccentric electron transparent portions within them. They were frequently seen lodged within peripherally-located mitochondria. Type 2 wall-forming bodies averaged 1.5 mum in diameter. The role of the two types of wall-forming bodies in forming the outer and inner layers of the wall of the oocyst was similar to that in other species of Eimeria. The oocyst wall was 0.2 mum thick and composed of a limiting membrane (20 nm thick), an outer layer (75 nm thick), and an inner layer (100 nm thick).