Behavioral response to selected feed attractants and stimulants in Pacific white shrimp, Litopenaeus vannamei     

Alberto J.P. Nunes  Marcelo V.C. S  Francisco Felipe Andriola-Neto  Daniel Lemos 《Aquaculture (Amsterdam, Netherlands)》2006,260(1-4):244-254

Nine commercial feeding attractants and stimulants for Litopenaeus vannamei were evaluated by observation of behavioral responses in animals allotted in one Y-maze aquarium apparatus. In the validation phase, fishmeal–Brazilian origin (FMBO); fishmeal–Peruvian origin (FMPO); blood meal (BM), meat and bone meal (MBM), squid meal (SM), fish oil (FO) and fish solubles (FS) were evaluated. There was also a control without stimulatory raw material. The tested materials were included at 3% in neutral gelatin pellets (wet basis). In each behavioral observation, two different ingredients were offered at the same time in equal quantities, being allotted in the end of each chamber's arm. In Phase II after system validation, the following commercial attractants were tested: 80% crude protein (CP) vegetable dried biomass (VDB₈₀), 68% CP vegetable dried biomass + glutamate + betaine (VDB₆₈), complex of amino acids (alanine, valine, glycine, proline, serine, histidine, glutamic acid, tyrosine and betaine) with enzymatically digested bivalve mollusk (CAA), condensed fish soluble protein (CFSP), squid liver meal (SLM), betaine (Bet), dried fish solubles–low biogenic amines (DFS_LB), dried fish solubles–high biogenic amines (DFS_HB) and whole squid protein hydrolysate (WSPH). Attractants were used at a 3% level wet basis with neutral gelatin, without any additional ingredient source available. The best four commercial attractants from this phase (CAA, CFSP, SLM and WSPH) were compared under 0.5% and 1.0% levels. In Phase I of the study, a higher percentage of choices were observed for FMPO and FMBO. BM and FO were the least chosen ingredients. In Phase II, the worst results were observed for Bet, DFS_HB and, mainly, for VDB₈₀ and VDB₆₈. When two-by-two comparisons were performed, results suggested that CFSP and CAA were the best commercial attractants tested. In the last phase, both CFSP and CAA at 1.0% level were significantly more chosen by shrimp than CFSP (0.5%), SLM (0.5 or 1.0%) or WSPH (0.5 or 1.0%). At both 0.5% and 1.0% levels, shrimp spent a similar amount of time feeding on CFSP and CAA. However, only CAA was statistically better than SLM and WSPH together. Further work is required to better elucidate the chemical drivers of chemostimulation for L. vannamei for each one of the attractants tested.  相似文献   

Isolation,in vitro propagation,genetic analysis,and immunogenic characterization of an Ehrlichia canis strain from southeastern Brazil     

Rosiane Nascimento Alves  Susana Elisa Rieck  Carlos Ueira-Vieira  Marcelo Bahia Labruna  Marcelo Emílio Beletti 《Journal of veterinary science (Suw?n-si, Korea)》2014,15(2):241-248

Amplification of the 16S rRNA gene from a blood sample obtained from a dog in southeastern Brazil was used to confirm a naturally acquired Ehrlichia (E.) canis infection. Following isolation and culturing of the new bacterial strain called Uberlândia, partial sequences of the dsb and p28 genes were obtained. The dsb partial sequence of the novel strain was 100% similar to dsb gene sequences of E. canis obtained from different geographic areas around the world. Conversely, the p28 partial sequence for the E. canis Uberlândia strain differed at several nucleotides from other sequences available in GenBank. To confirm the antigenic profile of the Uberlândia strain, an indirect immunofluorescence assay against E. canis antigens was performed using dog sera collected from two different areas in Brazil (Uberlândia and São Paulo). The results suggest that both antigens were able to identify animals seropositive for E. canis in Brazil since these Brazilian strains appear to be highly conserved.  相似文献   

Effects of progestagen exposure duration on estrus synchronization and conception rates of crossbreed ewes undergoing fixed time artificial insemination     

Wanessa Blaschi  Paula A. Lunardelli  Luciana S.R. Marinho  Marilu C. Max  Gustavo M.G. Santos  Katia C. Silva-Santos  Fabiana A. Melo-Sterza  Hernan Baldassarre  Thales R. Rigo  Marcelo M. Seneda 《Journal of veterinary science (Suw?n-si, Korea)》2014,15(3):433-437

Synchronization of estrus and ovulation are of paramount importance in modern livestock improvement programs. These methods are critical for assisted reproduction technologies, including artificial insemination and embryo transfer, that can increase productivity. In the current study, subcutaneous implants containing norgestomet were placed for long (14 days), medium (9 days), and short (5 days) periods of time in 70 crossbred ewes undergoing fixed-time artificial insemination. The resulting effects on estrus synchronization and conception rates were subsequently evaluated. Among the synchronized ewes, 85.7% (60/70) underwent estrus over a period of 72 h after progestagen treatment ceased. The shortest mean interval between withdrawal of the device and onset of estrus (34.2 ± 8.9 h) was observed in the G14 days of P4 group (p < 0.05). The conception rate of the G14 days of P4 group was statistically higher than that of the other groups (83.3% vs. 60.9% vs. 47.8%; p < 0.05). In conclusion, 14 days of norgestomet treatment produced higher conception rates and a greater number of pregnancies at the beginning of the breeding season.  相似文献   

Factors (type,colour, density,and shape) determining the removal of marine plastic debris by seabirds from the South Pacific Ocean: Is there a pattern?     

Valeria Hidalgo-Ruz  Guillermo Luna-Jorquera  Marcus Eriksen  Hanna Frick  Diego Miranda-Urbina  Matias Portflitt-Toro  Marcelo M. Rivadeneira  Christopher J.R. Robertson  R. Paul Scofield  Juan Serratosa  Cristián G. Suazo  Martin Thiel 《水产资源保护:海洋与淡水生态系统》2021,31(2):389-407

1. While floating near the sea surface plastic debris interacts with a number of external factors, including many different organisms. Seabirds have the most extensive documented history of interactions with plastics, through ingestion, entanglement, and nest construction.
2. In the present study, eight seabird species from the South Pacific Ocean were used as a proxy to determine potential patterns of removal of marine plastic debris, and three hypotheses were tested in relation to their feeding habits and nesting areas.
3. Plastics from abiotic compartments (Chilean continental coast, South Pacific Gyre, and Rapa Nui beaches) and biotic compartments (surface-feeding seabirds, diving seabirds, and nesting areas) were compared, according to their type, colour, shape, and density.
4. Continental beaches had a relatively wide range of colours and shapes, with many non-buoyant plastics. Samples from the South Pacific Gyre (SPG) and Rapa Nui (Easter Island) beaches comprised mainly hard, rounded, buoyant, and white/grey plastics.
5. These results indicate that the composition of floating plastics from terrestrial sources changes during transport with oceanic currents, reducing the proportion of prey-like plastics present in the subtropical gyres.
6. The stomach contents of surface-feeding and diving seabirds were dominated by hard, white/grey, and round plastic items, similar to plastics from the SPG, suggesting non-selective (accidental or secondary) ingestion.
7. Nesting areas had a more variable composition of brightly coloured plastics, suggesting a pattern of selective removal of plastics by seabirds, probably from oceanic sources.
8. The present study reveals extensive interactions of seabirds with plastics on a broader scale, which is highly relevant given that the impacts of plastics on seabirds are increasing worldwide, compromising their efficient conservation.

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Potential of a Fusarium eumartii culture filtrate on the screening for wilting resistance in potato     

Grisela L. Botta  María P. Dimarco  Alicia L. Melegari  Marcelo A. Huarte  Carlos A. Barassi 《Euphytica》1994,80(1-2):63-69

Summary Fusarium solani f.sp. eumartii Carp. Snyder and Hansen (Fusarium eumartii) is a soil inhabitant that induces the so-called Potato Wilt and Stem End Rot disease. Prior to wilting, the pathogen induces peculiar small bronze spots on the leaflets. Failure to isolate F. eumartii from infected leaflets suggests the involvement of a toxin in the disease. The fungus was grown in liquid Richard's medium and thereafter a filtrate was obtained dialyzing (MW cutoff 12,000–14,000) and sterilizing the culture by filtration (0.22 m). Potato leaves treated with both the pathogen or the filtrate showed symptoms of bronze spots and significantly higher electrolyte leakage when compared to controls. Tomato leaves showed neither bronze spots nor electrolyte leakage after plant inoculation with the pathogen or with the filtrate treatment. Both, the absence of visible symptoms and the lack of electrolyte leakage in tomato could be associated to a certain degree of host specificity of the F. eumartii filtrate towards potato. The filtrate also induced symptoms similar to infections by F. eumartii in adult plants and in vitro plantlets of cultivars Huinkul MAG and Kennebec. Callus responses to the filtrate were related to responses of the cultivars to the pathogen in greenhouse. These results show the potential of the culture filtrate of F. eumartii for use in screening for wilting resistance.  相似文献   

Canopy structure analysis for estimating forest regeneration dynamics and growth in <Emphasis Type="Italic">Nothofagus pumilio</Emphasis> forests     

Guillermo J. Martínez Pastur  Pablo L. Peri  Juan M. Cellini  María V. Lencinas  Marcelo Barrera  Horacio Ivancich 《Annals of Forest Science》2011,68(3):587-594

•Introduction   

Silviculture systems applied in Nothofagus pumilio forests are based on opening the canopy to stimulate natural regeneration by modifying light and soil moisture. The objective is to evaluate regeneration dynamics of N. pumilio along different forest canopy and solar radiation gradients.  相似文献   

Macronutrient accumulation in wheat crop (Triticum aestivum L.) with Azospirillum brasilense associated with nitrogen doses and sources     

Fernando Shintate Galindo  Marcelo Carvalho Minhoto Teixeira Filho  Salatiér Buzetti  José Mateus Kondo Santini  Eduardo Henrique Marcandalli Boleta  Willian Lima Rodrigues 《Journal of plant nutrition》2020,43(8):1057-1069

Abstract

New studies are needed to optimize the nitrogen (N) amount that can be applied to utilize the Azospirillum brasilense benefits. In addition, information regarding the interaction between the urease inhibitor and biological nitrogen fixation (BNF) and how they affect the macronutrients accumulation are also needed. We evaluate the effect of N sources and doses associated with A. brasilense regarding the macronutrients accumulation in straw and grains and wheat grain yield in tropical conditions. A randomized block experimental design was used with four replications in a 2?×?5?×?2 factorial arrangement as follows: two N sources (urea and urea with urease enzyme inhibitor NBPT; five N doses (0, 50, 100, 150, and 200?kg ha^?1) applied in topdressing; with and without A. brasilense inoculation. We found that an increase in N doses positively influenced the accumulation of macronutrients in straw and grains and the wheat grain yield. N sources have similar effects. Inoculation with A. brasilense increased accumulation of Mg and S in straw and P, Ca, and Mg in grains, regardless of the N dose. The inoculation with A. brasilense associated with 140?kg ha^?1 of N increased wheat grain yield. The inoculation can contribute in a more sustainable way to wheat nutrition and optimizing N fertilization.  相似文献   

Revisiting the taxonomic impediment     

de Carvalho MR  Bockmann FA  Amorim DS  de Vivo M  de Toledo-Piza M  Menezes NA  de Figueiredo JL  Castro RM  Gill AC  McEachran JD  Compagno LJ  Schelly RC  Britz R  Lundberg JG  Vari RP  Nelson G 《Science (New York, N.Y.)》2005,307(5708):353

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The anatomy of the world's largest extinct rodent     

Sánchez-Villagra MR  Aguilera O  Horovitz I 《Science (New York, N.Y.)》2003,301(5640):1708-1710

Phoberomys is reported to be the largest rodent that ever existed, although it has been known only from isolated teeth and fragmentary postcranial bones. An exceptionally complete skeleton of Phoberomys pattersoni was discovered in a rich locality of fossil vertebrates in the Upper Miocene of Venezuela. Reliable body mass estimates yield approximately 700 kilograms, more than 10 times the mass of the largest living rodent, the capybara. With Phoberomys, Rodentia becomes one of the mammalian orders with the largest size range, second only to diprotodontian marsupials. Several postcranial features support an evolutionary relationship of Phoberomys with pakaranas from the South American rodent radiation. The associated fossil fauna is diverse and suggests that Phoberomys lived in marginal lagoons and wetlands.  相似文献   

Development of transgenic fungi that kill human malaria parasites in mosquitoes     

Fang W  Vega-Rodríguez J  Ghosh AK  Jacobs-Lorena M  Kang A  St Leger RJ 《Science (New York, N.Y.)》2011,331(6020):1074-1077

Metarhizium anisopliae infects mosquitoes through the cuticle and proliferates in the hemolymph. To allow M. anisopliae to combat malaria in mosquitoes with advanced malaria infections, we produced recombinant strains expressing molecules that target sporozoites as they travel through the hemolymph to the salivary glands. Eleven days after a Plasmodium-infected blood meal, mosquitoes were treated with M. anisopliae expressing salivary gland and midgut peptide 1 (SM1), which blocks attachment of sporozoites to salivary glands; a single-chain antibody that agglutinates sporozoites; or scorpine, which is an antimicrobial toxin. These reduced sporozoite counts by 71%, 85%, and 90%, respectively. M. anisopliae expressing scorpine and an [SM1](8):scorpine fusion protein reduced sporozoite counts by 98%, suggesting that Metarhizium-mediated inhibition of Plasmodium development could be a powerful weapon for combating malaria.  相似文献