A scanning electron microscope study of Raillietascaris varani (Baylis et Daubney, 1922) (Nematoda: Ascaridioidea).

The Raillietascaris varani (Baylis et Daubney, 1922), parasitic in the Indian monitor lizard, Varanus monitor (L.), was studied by scanning electron microscopy (SEM). A surface topography of the worm, especially the head and male tail, were described, illustrated and discussed with regard to the available data on this species, and also other species of ascaridoid nematodes. The present study confirms the previous observations from Sprent (1985), and also provides some additional information concerning the microtopography of the worm which might be useful in comparative studies on the Ascaridoidea.     

Influence of overstory density on ecophysiology of red oak (Quercus rubra) and sugar maple (Acer saccharum) seedlings in central Ontario shelterwoods

A field experiment was established in a second-growth hardwood forest dominated by red oak (Quercus rubra L.) to examine the effects of shelterwood overstory density on leaf gas exchange and seedling water status of planted red oak, naturally regenerated red oak and sugar maple (Acer saccharum Marsh.) seedlings during the first growing season following harvest. Canopy cover of uncut control stands and moderate and light shelterwoods averaged 97, 80 and 49%, respectively. Understory light and vapor pressure deficit (VPD) strongly influenced gas exchange responses to overstory reduction. Increased irradiance beneath the shelterwoods significantly increased net photosynthesis (P(n)) and leaf conductance to water vapor (G(wv)) of red oak and maple seedlings; however, P(n) and G(wv) of planted and naturally regenerated red oak seedlings were two to three times higher than those of sugar maple seedlings in both partial harvest treatments, due in large part to decreased stomatal limitation of gas exchange in red oak as a result of increased VPD in the shelterwoods. In both species, seedling water status was higher in the partial harvest treatments, as reflected by the higher predawn leaf water potential and seedling water-use efficiency in seedlings in shelterwoods than in uncut stands. Within a treatment, planted and natural red oak seedlings exhibited similar leaf gas exchange rates and water status, indicating little adverse physiological effect of transplanting. We conclude that the use of shelterwoods favors photosynthetic potential of red oak over sugar maple, and should improve red oak regeneration in Ontario.     

Restriction Enzyme Analysis of Tissue Culture-adapted Velogenic Newcastle Disease Virus

A velogenic Newcastle disease virus isolate typed to belong to group C1 by monoclonal antibody typing was adapted 50 times in chicken embryo fibroblast cell culture and 60 times in Vero cells. At every 10th passage the virus was characterized on the basis of mean death time, intracerebral pathogenicity indices and viral titration studies. A gradual reduction in the virulence of the virus was noted as the passage number increased. RT-PCR of a 254 bp region of the fusion gene encompassing the fusion protein cleavage site was carried out for the virulent as well as cell culture-adapted viruses at every 10th passage level. The amplicons were subsequently digested with three restriction enzymes, viz. AluI, HaeIII and PstI. It was found out that there was difference in banding patterns between the virulent and adapted viruses, indicating nucleotide substitutions in the virulent virus when it was sequentially passaged onto cell culture systems.     

THE SOCIAL AND ECONOMIC IMPACTS OF SEMI-INTENSIVE AQUACULTURE ON BIODIVERSITY

As a result of the concern and debate about the impacts of intensive aquaculture development on biodiversity, semi-intensive aquaculture is being considered as an alternative. Although the biophysical impacts of aquaculture on biodiversity have been examined, there is only limited understanding of the social and economic impacts of aquaculture on biodiversity, and especially the impacts of the shift from intensive to semi-intensive systems. The purposes of this article are twofold: (1) to identify and discuss the social and economic impacts of aquaculture on biodiversity, and (2) to examine the impacts while moving from intensive to semi-intensive systems. After discussing the findings of our study, we provide some recommendations as to how to minimize social and economic impacts of aquaculture on biodiversity by moving to a lower intensity aquaculture system. The integrated agriculture-aquaculture farming systems, stakeholder involvement in management, and well defined basic rights are aquaculture systems that contribute to conservation of biodiversity.     

Impact of the Community‐based Fish Culture System on Expenditure and Inequality: Evidence from Bangladesh

This study investigated the impact of a Community‐based Fish Culture (CBFC) system on household expenditure and how expenditure inequality in the fish‐producing communities has changed due to involvement in the CBFC system. Six floodplains, comprising three project sites and three controls, were chosen from three river basin areas of Bangladesh; data for this study were collected for a period of 3 yr. A propensity score matching method was used to evaluate the impact of CBFC on household expenditure; while a Gini coefficient and Gini decomposition were used to estimate inequality. The results show that the CBFC system has a positive and significant impact on fish culture community household expenditure. Results also reveal that the CBFC system has an equalization effect on food, clothing, and healthcare expenditure. Furthermore, this management system helps to distribute total expenditure 15% more equally among the fish culture communities.     

Genetic analysis of important antioxidant compounds in cabbage (Brassiaca oleracea var. capitata L.)

The paucity of research on development of antioxidant-rich hybrids in cabbage by utilizing combining ability estimates, gene action, and heterosis motivated us to undertake this study. We made 60 crosses between 5 cytoplasmic male-sterile lines and 12 male-fertile testers during the summer of 2015, as per the line × tester design. The seedlings of all the parents and 60 F₁ crosses, along with three checks, were transplanted during the Rabi (winter) season of 2015–2016 and evaluated using a randomized complete-block design. Combining ability, gene action, and heterosis were determined for different antioxidant compounds. Experimental results revealed that the range of cupric ion reducing antioxidant capacity (CUPRAC) [parents = 1.26–7.33 and hybrids = 0.04–6.54 μmol trolox/g], ferric reducing ability of plasma (FRAP) [parents = 1.65–4.76 and hybrids = 0.16–4.67 μmol trolox/g], β-carotene (parents = 0.44–2.29 and hybrids = 0.04–1.89 μg/100 g), and chlorophyll-a (parents = 0.71–4.08 and hybrids = 0.19–3.08 mg/g f.w.) for hybrids was lower than that of the parents because of outbreeding depression. The parental lines 6A, 208A, 83-5-8, and Sel-5-83-6 were found to be good general combiners for most of the antioxidant compounds studied. Based on the mean performance, specific combining ability effects and heterosis, five hybrid combinations viz., 9A × KIRC-8 for CUPRAC and FRAP; 208A × C-122 for ascorbic acid; 6A × Chhaki-2 for total carotenoids and β-carotene; 831A × Chhaki-2 for chlorophyll-a; and 6A × 83-5-8 for chlorophyll-b and total chlorophyll content, were most promising. The ratio of general combining ability (GCA) and specific combining ability (SCA) variances, i.e., [2 σ²g/(2σ²g + σ²s)], which reflects the relative importance of GCA versus SCA, was less than unity for different antioxidant compounds, which implied that for these traits, nonadditive gene effects were more important than additive effects. The numerical values of range for contribution of lines × testers interaction for different traits (41.47–70.18%) were found to be higher than the individual contribution of lines (11.24–47.22%) and testers (8.31–21.76%). Hence, heterosis could be exploited for developing antioxidant-rich hybrid cabbage.     

Molecular identification of a Candidatus phytoplasma (Group16SrV-D) coding partial uvrB gene and degV gene on a new host – mesta (Hibiscus sabdariffa) – with phyllody and reddening of leaves in India

Mesta (Hibiscus sabdariffa) is an important bast fiber crop. In August 2011, there was an outbreak of a phytoplasma-like disease on H. sabdariffa in different villages of the northern coastal mesta-growing region of Andhra Pradesh, India, covering mainly two districts – Srikakulam and Vijayanagaram. The infected plants showed characteristic symptoms such as phyllody and reddening of leaves. PCR with P1/P7 universal primer pair of 16 S rDNA yielded amplicons of 1850 bp from all symptomatic mesta leaf samples similar to samples of brinjal little leaf (phytoplasma positive reference control). However, asymptomatic samples were not amplified. Multiplex nested-PCR showed simultaneous amplification of DNA fragments with phytoplasma specific primers, viz., P1/P7 universal primer pair of 16 S rDNA, nested primer pair R16F2n/R2, uvrB and DegV gene-specific uvrB-degVF/R primer generating amplicons of 1850 bp, 1200 bp and 1023bp, respectively. However, SecY-map gene specific primer SecY-mapF/R was not amplified. The 1023 bp nucleotide sequence of uvrB and DegV gene of the phytoplasma was deposited in the GenBank (NCBI) with the accession no. JX975061. NCBI BLASTn analysis of the 1023 bp products showed that the phytoplasma strain belonged to elm yellows group (16SrV-D). This is the first report that Hibiscus sabdariffa is infected by a phytoplasma and we named it mesta phyllody disease (MPD).     

DISAGGREGATED ANALYSIS OF FISH SUPPLY,DEMAND, AND TRADE IN ASIA: BASELINE MODEL AND ESTIMATION STRATEGY

ABSTRACT

Quantitative modeling of fish supply, demand and trade is a useful tool for analyzing recent structural changes, such as the rapid development of aquaculture. Existing models are, however, limited by their use of highly aggregated fish categories and assumed (rather than estimated) elasticities. This paper outlines an estimation strategy and a multiproduct equilibrium model for disaggregated analysis of fish supply, demand, and trade. The model is composed of a producer, consumer and trade core, and is specified to accommodate special features of the fish sector. The estimation and modeling strategy also address common data problems, such as heterogeneity of fish types, diversity of production categories, and so forth. The model has been applied to nine major fish producers in developing Asia.     

Fish to 2030: The Role and Opportunity for Aquaculture

Seafood sector can contribute to the global food supply in an important way, and provide an important source of animal protein. Based on observed regional trends in seafood production and consumption and using a global, partial-equilibrium, multi-market model, this study investigates what the global seafood market may look like in 2030. The model projects that the total fish supply will increase from 154 million tons in 2011 to 186 million tons in 2030, with aquaculture entirely responsible for the increase. The fastest aquaculture growth is expected for tilapia and shrimp, while the largest expansion is expected in India, Latin America and Caribbean and Southeast Asia. Fast-growing seafood demand in China and elsewhere represents a critical opportunity for global fisheries and aquaculture to improve their management and achieve sustainable seafood economy.     

River dolphin distribution in regulated river systems: implications for dry‐season flow regimes in the Gangetic basin

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