Characterization of antibiosis and antixenosis to the whitefly silverleaf <Emphasis Type="Italic">Bemisia tabaci</Emphasis> B biotype (Hemiptera: Aleyrodidae) in several squash varieties

The objective of this study was to investigate the potential resistance mechanisms to Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) B biotype, in eight Cucurbita pepo varieties. Attractivity, oviposition preference, and nymphal development were evaluated under greenhouse and laboratory conditions. Variety Bianca was the least attractive to adult whiteflies in multi-choice tests. The whiteflies showed oviposition nonpreference (antixenosis) for Novita Plus, Bianca and Sandy in multi-choice test, and similar results were observed in no-choice tests with varieties Bianca, Novita, Caserta Cac and Sandy. Sandy expressed high antibiosis levels against whitefly nymphs, leading to 63.9% mortality. The high level of resistance in variety Sandy can serve as base for genetic improvement of C. pepo focusing on the development of resistant varieties to B. tabaci B biotype.     

Bacterial pigment for Nile tilapia feeding

The aim of this study was to evaluate the effects of different carotenoids sources in tilapia fish diets on the animals’ performance and fillets characteristics. Nine hundred and sixty tilapias, Oreochromis niloticus, averaging 15 g were distributed into 24 tanks to receive one of the six treatments (four repetitions) for 80 days: basal diet with no pigment (control group), basal diet with 350 mg/kg astaxanthin 10 % and basal diets added of four different concentrations of Rubrivivax gelatinosus biomass (175, 350, 700 and 1400 mg/kg). Variables analyzed included feed consumption, weight gain, feed conversion and specific growth rate for the animals and pH, proximate composition, carotenoids, polyunsaturated fatty acids and color for the fillets. Productive parameters did not differ statistically. Moisture content was lower on the fillets of treatments with pigments. The protein contents on the fillets of diets supplemented with the bacterial biomass were higher than in control group, while pH, minerals and lipids did not vary among treatments. Lightness and yellowness did not differ among the treatments, but redness and carotenoids contents were higher for all the groups that received the pigments than for the control group. The ratio of polyunsaturated fatty acids n-6/n-3 was improved with the dietary biomass. So, it was concluded that the use of the pigmenting ingredients did not alter productive parameters but increased redness and carotenoids contents in the fillets. Moreover, the use of R. gelatinosus biomass also increased the protein contents and improved the fatty acids profile in the fillets.     

Investigation of insecticidal activity of rye α-amylase inhibitor gene expressed in transgenic tobacco (Nicotiana tabacum) toward cotton boll weevil (Anthonomus grandis)

Innumerable proteinaceous α-amylase inhibitors have been isolated and identified from different plant species. Among them, an α-amylase inhibitor gene with bioinsecticidal potential toward Anthonomus grandis (cotton boll weevil) was previously identified in rye seeds (Secale cereale). This cereal inhibitor was expressed in tobacco plants (Nicotiana tabacum) under control of phytohemaglutinin promoter by using Agrobacterium tumefasciens - mediated transformation. Presence of αBIII-rye gene and further protein expression were confirmed by PCR and Western blot analysis, respectively. Immunological assays indicated that the recombinant inhibitor was expressed in concentration range from 0.1% to 0.28% (w:w) of the total protein in tobacco seeds of R₀ plants. From 14 independent transformants, five plants with expression levels between 0.20% and 0.28% in seeds were in vitro assayed against A. grandis amylolytic enzymes causing clear inhibition. Moreover, bioassays using transgenic seed flour mixture for artificial diet produced 74% mortality in A. grandis first larval instar. These data suggest that rye inhibitor could be a promising biotechnological tool for produce transgenic cotton plants with an increased resistance to cotton boll weevil. Moreover, αBIII-rye gene should be considered a potential compound for a pyramiding strategy aiming to delay insect-resistance.     

Evaluating ipê (Tabebuia, Bignoniaceae) logging in Amazonia: Sustainable management or catalyst for forest degradation?

Prized for their dense, rot-resistant wood, Tabebuia impetiginosa and T. serratifolia (vernacular name = ipê) are among the most valuable Amazonian timbers. We analyzed the geographical extent, spread and trajectory of ipê logging in Brazilian Amazonia, and evaluated harvest pressure on this forest resource. We also examine Tabebuia population response to reduced-impact logging, a more ecologically benign alternative to destructive conventional harvest practices in Amazonia. Based on eight years of population monitoring at multiple sites in the eastern Brazilian Amazon, we project second harvest ipê yields in forests logged using RIL under legally allowable (90% of commercial stems) and reduced (70%) harvest intensities.In recent years ipê harvests have declined or ceased in the majority of old logging frontiers in eastern Amazonia while spreading to new logging frontiers in central and southwestern Amazonia. With current timber market prices, transportation infrastructure and harvesting costs, logging of ipê would be profitable in an estimated 63% of the Brazilian Amazon; in the more remote logging frontiers only logging of ipê and a few other high-value timbers is currently profitable. All populations of T. impetiginosa and T. serratifolia in northeastern forests showed drastic population declines over multiple RIL harvests in simulations, with no indication of population recovery over the long term. We conclude from study of Tabebuia populations in eastern Amazonia and modeling of response to logging that these two species are endangered by logging activity and merit additional protection under forest legislation.     

Epidermal response of the Japanese eel to environmental stress

Nonspecific responses of Japanese eels to environmental stress were monitored by assaying various lytic activities in eel epidermal extract. In fish maintained at 10 and 30 °C for up to 10 days, epidermal proteolytic activities due to serine protease and aminopeptidase and hemolytic activity varied within a 2-fold value range. Other proteolytic activities, due to cathepsins B and L, in the fish at 30 °C increased for up to 8 days and were 3.4 and 2.9-fold over those in fish maintained at 10 °C, respectively. This was accompanied by a 3.0-fold increase in bacteriolytic activity. Other forms of stress were exerted on the fishes by immersing them in a suspension of Flavobacterium columnare or giving them intraperitoneal injections of Edwardsiella tarda over 72 h. Although serine protease and aminopeptidase activities and hemolytic activity in the fishes exposed to F. columnare changed marginally, and were similar to those in the control fish, cathepsins B and L activities in the infected fishes increased more than 1.5-fold over their initial values over a 48 h period, along with a 4.5-fold increase in bacteriolytic activity. No marked change was detected in any of the lytic activities of the fishes exposed to E. tarda. These findings indicate that epidermal cathepsins B and L probably participate in bacteriolysis associated with Japanese eel skin and that their activities are elicited by environmental stimuli and may be an important nonspecific response of eels. Abbreviations: Cbz – carbobenzoxy; MCA – 4-methylcoumaryl-7-amide.     

Erratum to: Water management strategies for hydropower annexation at existing irrigation dams in Japan

Paddy and Water Environment -     

The phylogeny of Anguillicola crassus and A. globiceps based on partial 18S ribosomal RNA sequences

The parasitic nematodes Anguillicola crassus and A. globiceps infect the swimbladder of eels. To investigate the relationship of these species at the molecular level, the small subunit ribosomal RNA (18S rRNA) genes of A. crassus and A. globiceps were cloned and their nucleotide sequences determined. The 18S rRNA gene of A. crassus and A. globiceps were found to have similar lengths (886 and 888 base pairs, respectively) and demonstrated extensive similarity in their nucleotide sequences, showing 98.8% homology. However, the sequence homology of the 18S rRNA gene of A. crassus with that of other nematodes was found to be in the range of 72.7–89.0% homology, whilst that of A. globiceps was in the range of 73.1–89.4% homology. A phylogenetic reconstruction showed A. crassus to be closely related to A. globiceps. The analysis of nucleotide sequences of the 18S rRNA gene of fish parasites has proven useful in supporting species status and phylogenetic relationships.     

Effects of thermal stress on skin defence lysins of European eel, Anguilla anguilla L.

Fish skin contains a variety of humoral defence lysins which have an integral role in fish immunity because of the ability of these proteins to destroy invading substances ( Alexander & Ingram 1992 ). These lysins generally comprise bacteriolysins, proteolysins and haemolysins. The lysins seem to be either individually or cooperatively stimulated to respond to pathogenic infection and environmental stress, such as ionic, osmotic, thermal and pollution stress ( Shephard 1994 ; Rice, Kergosien & Adams 1996 ; Bly, Quiniou & Clem 1997 ). There have only been a few reports on these lysins ( Al-Hassan, Thomson, Ali & Criddle 1987 ; Aranishi, Mano, Nakane & Hirose 1998 ). The present paper describes thermal effects on defence lysis, such as proteolysis, bacteriolysis and haemolysis, in the skin of the European eel, Anguilla anguilla L.     

Immunological characterization of protective antigens prepared by alkaline treatment of whole cells and from the culture filtrate of Erysipelothrix rhusiopathiae.

Culture filtrate and alkaline-extracted antigens from whole cells of an attenuated strain of Erysipelothrix rhusiopathiae (strain Koganei: serovar 1a) were fractionated with ammonium sulfate; both induced protective immunity in mice. Sephadex G-200 gel filtration revealed three protein fractions in the alkaline-extracted antigen and four protein fractions in the culture filtrate antigen. A fraction in the alkaline extract (NaOH P-2) and in the culture filtrate (CF P-2) induced protection in mice against challenge with a different serovar strain (strain Agata: serovar 5). Anti-NaOH P-2 and anti-CF P-2 mouse sera were protective against different serovars. Glycoprotein fraction derived from CF P-2 antigen by affinity chromatography with Con A-Sepharose 4B did not show protective activity. Western blotting between the antisera (anti-NaOH P-2, Anti-CF P-2 and anti-Koganei strain) and the antigens (NaOH P-2, and sonicated antigens of Agata, Fujisawa and Koganei strains) showed strong recognition of the same bands at 62, 42 and 41 kDa.