Molecular mapping of Asian soybean rust resistance in soybean landraces PI 594767A,PI 587905 and PI 416764

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi, is one of the most serious diseases of soybean. The soybean landraces PI 594767A, PI 587905 and PI 416764 previously showed high levels of resistance to a wide range of ASR fungus, while the genetic basis of the resistance has yet to be understood. In this study, the ASR resistance loci were mapped using three independent mapping populations, POP‐1, POP‐2 and POP‐3 derived from crosses BRS184 × PI 594767A, BRS184 ×  PI 587905 and BRS184 × PI 416764, respectively. In each population, the resistance to ASR segregated as a single gene, but the resistance was dominant in PI 594767A and PI 587905 and incompletely dominant in PI 416764. The resistance genes from both PI 594767A and PI 587905 were mapped on chromosome 18 corresponding to the same location as known resistance locus Rpp1. Quantitative trait locus (QTL) analysis performed on POP‐3 identified the putative ASR resistance locus in PI 416764 on the defined region of chromosome 6 where Rpp3 was located. The QTLs detected by the mapping explained about 67–72% of the phenotypic variation in POP‐3. Cluster analysis based on disease reactions to 64 ASR populations demonstrated the presence of at least two types of functional resistant Rpp1 alleles: strong and weak allele(s), e.g. soybean accession PI 594767A and PI 587905 carry the strong resistant Rpp1 allele(s). Introducing or pyramiding strong Rpp1 allele(s) in elite soybean cultivars is expected to be useful against the South American rust population.     

Neuroendocrine,Metabolic and Genomic Cues Signalling the Onset of Puberty in Females

Puberty is the result of a dynamic interaction between genetic factors and environmental cues, all of which lead to the attainment of reproductive capacity. Thus, significant changes in hormone secretion occur from the pre‐pubertal to the pubertal stage. The objective of this review is to provide an update of some endocrine, physiological, metabolic and genetic concepts involved in the establishment of the hypothalamic‐hypophyseal‐gonadal axis function promoting the onset of the reproductive function during puberty. To achieve this purpose, basic aspects of the function of the hypothalamic‐hypophyseal‐gonadal axis, the control of the axis by neurotransmitters and the interaction between reproductive function and metabolic status will be considered. Finally, the role of the novel kisspeptin system and the GPR54 receptor as modulators of puberty will be considered, in addition to the hierarchical expression of the main genes acting as regulators of the onset of puberty.     

Co‐culture of sea cucumber Holothuria scabra and red seaweed Kappaphycus striatum

Commercially valuable sea cucumbers are potential co‐culture species in tropical lagoon environments, where they may be integrated into established aquaculture areas used for seaweed farming. In the current study, wild‐caught juvenile sea cucumbers, Holothuria scabra, and red seaweed Kappaphycus striatum were co‐cultured on Zanzibar, United Republic of Tanzania. Sea cucumbers (97 g ± 31 SD, n = 52) were cultured in mesh enclosures at initial cage stocking densities of 124 ± 21 SD and 218 ± 16 SD g m^?2 under seaweed culture lines. Over 83 days, individual growth rate (1.6 g d^?1 ± 0.2 SD) of sea cucumbers at low stocking density was significantly higher (χ² = 8.292, d.f. = 1, P = 0.004) than at high‐stocking density (0.9 g d^?1 ± 0.1 SD). Seaweed individual growth rates [6.27 (±0.3 SE) g d^?1] were highest in co‐culture with sea cucumber at low density but did not differ significantly from high sea cucumber density or seaweed monoculture treatments (χ² = 3.0885, d.f. = 2, P = 0.2135). Seaweed growth varied significantly (χ² = 35.6, d.f. = 2, P < 0.0001) with sampling period, with the final sampling period resulting in the highest growth rate. Growth performance for seaweed and sea cucumbers (χ² = 3.089, d.f. = 2, P = 0.21 and χ² = 0.08, d.f. = 1, P = 0.777 respectively), did not differ significantly between monoculture and co‐culture treatments, yet growth in co‐culture was comparable with that reported for existing commercial monoculture. Results indicate H. scabra is a highly viable candidate species for lagoon co‐culture with seaweed. Co‐culture offers a more efficient use of limited coastal space over monoculture and is recommended as a potential coastal livelihood option for lagoon farmers in tropical regions.     

Partial replacement of fishmeal with biofloc meal in the diet of postlarvae of the Pacific white shrimp Litopenaeus vannamei

This study evaluated the potential for the replacement of fishmeal (FM) by biofloc meal (BM) in the diet of Litopenaeus vannamei postlarvae. Four isonitrogenous (437.42 g kg^?1) and isocaloric (19.84 kJ g^?1) diets were formulated, in which FM was replaced with BM at 0% (T0), 7.5% (T7.5), 15% (T15) and 30% (T30). A commercial diet (CD) was used as reference. The study was conducted over 42 days in 50 L tanks connected to a water recirculation system. All tanks were stocked with three postlarvae (initial weight 0.0023 g) per litre. Shrimp survival, weight gain (WG), final weight (FW), specific growth rate (SGR) and protein efficiency ratio (PER) were measured. Survival rates were high (>91.1%) in all treatments. As the T30 treatment returned a significantly (<0.05) better performance in WG, FW, SGR and PER than all other treatments, partial replacement of FM with BM does not appear to affect productivity. In fact, a regression analysis indicated that a FM to BM replacement level of over 20% may actually improve shrimp growth. In addition to providing a cost‐effective alternative ingredient for L. vannamei postlarvae diets, the production of meal also represents a more sustainable way of disposing of the excess of biofloc produced by BFT systems.     

The effect of density in larval rearing of the pullet carpet shell Venerupis corrugata (Gmelin, 1791) in a recirculating aquaculture system

The pullet carpet shell Venerupis corrugata is an economically valuable species in several European countries, however, nowadays stocks are under high fishing pressure. Hatchery production of juveniles for release is a major contributor to strengthen the stock and consequently improve the sustainability of the natural stocks. This study aimed to determine the feasibility of rearing V. corrugata larvae with different larval densities (10, 40 and 200 larvae per mL) in a recirculating aquaculture system (RAS), compared with the traditional larval rearing methodology (Batch). The mean survival, growth and metamorphic rate of V. corrugata larvae in RAS was higher (11.1%; 71.3 μm; 21.6% respectively) than in the Batch system, in all tested densities. The larval growth was not affected by the initial density until 40 larvae per mL, however, 200 larvae per mL decreased the larval growth in length nearly 54 μm. The larval rearing time was shortened in 2 days in the RAS system. The physical, chemical and microbiologic parameters suggested that the tested densities were not excessive to disturb the biofilter stability of RAS. The V. corrugata larval rearing performed at high larval stocking densities in RAS system present a reduction in the operating costs to produce this species.     

Seroprevalence of and risk factors for Toxoplasma gondii in sheep raised in the Jaboticabal microregion, São Paulo State, Brazil

Seroprevalence of and risk factors for toxoplasmosis in sheep from different properties in the Jaboticabal microregion, São Paulo State, Brazil were determined. Antibodies to Toxoplasma gondii were found in sera of 52.0% of 488 sheep tested by indirect fluorescent antibody test (IFAT ? 64). T. gondii seropositivity in sheep was significantly associated with gender of the sheep, pasturing system, contact with cats, and the use of mineral supplements and the type of feed.     

Chemical Attributes of Soil and Forage Yield of Pasture Recovered with Phosphate Fertilization and Soil Management

Extensive and semi-extensive pastures are the basis of Brazilian livestock production. However, much of it is degraded or in degradation process, with low stocking rate per area. Even with this problem, this management type is 60% and 50% of Australia’s and the United States’ production costs, respectively. In order to research alternatives for Urochloa decumbens degraded pasture recovery in an Oxisol, Stylosanthes (Stylosanthes spp.) “Campo Grande” cultivar was introduced and phosphate fertilization was applied. The experimental design was of randomized blocks, 7 × 2 × 2 factorial design, with four replicates, involving seven systems to introduction (U. decumbens control; partial desiccation with 1.5 L ha^?1 glyphosate, total desiccation with 3.0 L ha^?1 glyphosate; direct planting; scarification, harrowing, and plowing + harrowing), phosphate fertilizer presence or absence, and two evaluation periods. “Campo Grande” Stylosanthes legume introduction increased shoot dry weight (SDW) yield, except in direct planting. Phosphorus fertilization increased SDW yield only in the first period, and Stylosanthes introduction in the pasture has not changed soil chemical properties. Phosphorus (P) fertilization also provided available P and exchangeable calcium (Ca²⁺) content in the soil increase, in addition to sum of bases and cation exchange capacity increase.