Growout production of camouflage grouper, Epinephelus polyphekadion (Bleeker), in a tank culture system

Growout production of the camouflage grouper, Epinephelus polyphekadion (Bleeker), in a 10-m³-capacity fibreglass tank culture system was evaluated, using hatchery-produced fingerlings (56-59 g initial weight) at stocking densities of five, 15 and 45 fish m^?3. During the first 9 months of a 12-month growout period, the fish were fed twice a day with a moist pellet feed containing 40.9% protein. From month 10 onwards until harvest, the fish were fed moist pellets in the morning and trash fish in the evening at a 1:1 ratio. The final weight of fish at harvest was up to 900 g, with mean weights of 544.6 ± 170.72 g at five fish m^?3, 540.2 ± 150.82 g at 15 fish m-^?3 and 513.3 ± 134.52 g at 45 fish m^?3. The results showed no significant differences (P > 0.05) in growth rate and fish size between the different stocking densities tested. The average daily growth rate ranged from 0.62 to 3.38 g fish^?1 day^?1, with mean weights of 1.49 ± 0.74 g fish^?1 day^?1 at five fish m^?3 through 0.53 to 2.38 g fish^?1 day^?1, 1.32 ± 0.57 g fish^?1 day^?1 at 15 fish m^?3 to 0.48-3.32 g fish^?1 day^?1 and 1.31 g fish^?1 day^?1 at 45 fish m^?3 stocking density. Although up to 100% survival was observed at the lowest stocking density, the survival rate significantly decreased (P < 0.05) with increasing stocking density. The food conversion ratio (FCR) significantly decreased (P <0.05) with increasing stocking densities, showing efficient feed utilization with increasing stocking densities of E. polyphekadion. The FCR averaged 2.1 at a stocking density of 45 fish m^?3. The yield in terms of kg fish produced m^?3 of water used in the culture system significantly increased (P < 0.001) from five to 45 fish m^?3. The yield averaged 17.3 ±0.53 kg m^?3 at a stocking density of 45 fish m^?3. The present results show that the present tank culture system could sustain more biomass in terms of increasing fish stocking densities. The growth performance of E. polyphekadion observed during this investigation has been reviewed with other grouper species.     

Management strategies of mealybug pests of citrus in mediterranean countries

Six mealybug species have been reported as citrus pests in the Mediterranean Basin: the citrus mealybugPlanococcus citri (Risso), the citriculus mealybugPseudococcus cryptus Hempel, the longtailed mealybugPseudococcus longispinus (Targioni-Tozzetti), the citrophilus mealybugPseudococcus calceolariae (Maskell), the obscure mealybugPseudococcus viburni (Signoret) and the spherical mealybugNipaecoccus viridis (Newstead). Some of these species,e.g. N. viridis, have recently been introduced into the region and are still spreading. Mealybugs are usually occasional or minor pests of citrus, but some species can reach key pest status. Mealybug management strategies in citrus have been based mostly on classical biological control and, to a lesser extent, on augmentative releases. However, chemical control is widely used, mainly because of the poor adaptation of the principal natural enemies to the climatic conditions of the Mediterranean. The application of pheromones is still restricted to monitoring the citrus mealybug, whose sex pheromone is commercially available. Mass trapping and mating disruption should be considered for possible use in IPM programs as an alternative method to supplementary chemical treatments. Enhancement of biological control through management of ant populations is another promising tactic for control of mealybugs. Strategies for managing mealybug pests of citrus, and possible levels of integration of different tactics according to the pest status, are discussed. http://www.phytoparasitica.org posting Oct. 3, 2004.     

Two subpopulations of Colletotrichum acutatum are responsible for anthracnose in strawberry and leatherleaf fern in Costa Rica

Strawberry, Fragaria × ananassa, and leatherleaf fern, Rumohra adiantiformis, are two important crops in Costa Rica. One of the most severe diseases affecting these crops is anthracnose, caused by members of the fungal genus, Colletotrichum (teleomorph; Glomerella). Eighty single-spore isolates from strawberry and leatherleaf fern were identified as Colletotrichum acutatum by species-specific PCR, and were further characterised by Universally Primed PCR (UP-PCR) fingerprinting analysis, and sequence analysis of the ribosomal internal transcribed spacer (ITS) region. Morphological differences, genotypic variation revealed by UP-PCR fingerprinting analysis, and a single sequence polymorphism within the ITS2 region were found between the isolates from strawberry and leatherleaf fern, respectively. The UPGMA cluster analysis of the fingerprints clearly separated the isolates derived from strawberry and leatherleaf fern into two different clusters. Pathogenicity assays on detached strawberry fruits confirmed the apparent difference between the two groups of isolates. It is therefore suggested that the pathogens responsible for strawberry anthracnose fruit rot and leatherleaf fern anthracnose in Costa Rica, belong to two distinct subpopulations of C. acutatum.     

Reproductive development, GnRHa-induced spawning and egg quality of wild meagre (Argyrosomus regius) acclimatised to captivity

The objective of the study was to acclimatise wild-caught meagre (Argyrosomus regius) to captivity to produce viable eggs for aquaculture production. Twelve meagre (3 males and 9 females, mean weight?=?20?±?7?kg) were caught and transported to a land-based facility on 26 October 2006. During, March to June 2007, all three males were spermiating and five of the nine females were in vitellogenesis with mean maximum oocyte diameter ≥550?μm. No spontaneous spawning was observed. Two hormone treatments, either a single injection of gonadotropin-releasing hormone agonist (GnRHa, 20?μg?kg(-1) for females and 10?μg?kg(-1) for males) or a slow-release implant loaded with the same GnRHa (50?μg?kg(-1) for females and 25?μg?kg(-1) for males), were used to induce spawning on three different dates on 26 March 2007, 4 May 2007 and 18 April 2008. From each spawning event, the following parameters were determined: fecundity, number of floating eggs, egg size, fertilisation and hatching success, unfed larval survival, and proximal composition and fatty acid profile of the eggs. In 2007, two females that were injected on 26 March and 4 May spawned a total of 5 times producing 9,019,300 floating eggs and a relative fecundity of 198,200 eggs?kg(-1) and two different females that were implanted on the same dates spawned 14 times producing 12,430,000 floating eggs and a relative fecundity of 276,200 eggs?kg(-1). In 2008, a pair that was implanted spawned five times producing a total of 10,211,900 floating eggs and a relative fecundity of 527,380 eggs?kg(-1). The latency period was 48-72?h. Parameters were compared between hormone treatments, date of hormone induction and parents determined by microsatellites. Percentage hatch and egg size were 70?±?0.3% and 0.99?±?0.02?mm, respectively, for GnRHa-implanted fish and were significantly higher (P?相似文献   

Connectivity of sediment transport in a semiarid environment: a synthesis for the Upper Jaguaribe Basin,Brazil

Purpose

Hydrosedimentological studies conducted in the semiarid Upper Jaguaribe Basin, Brazil, enabled the identification of the key processes controlling sediment connectivity at different spatial scales (10⁰–10⁴ km²).

Materials and methods

Water and sediment fluxes were assessed from discharge, sediment concentrations and reservoir siltation measurements. Additionally, mathematical modelling (WASA-SED model) was used to quantify water and sediment transfer within the watershed.

Results and discussion

Rainfall erosivity in the study area was moderate (4600 MJ mm ha^?1 h^?1 year^?1), whereas runoff depths (16–60 mm year^?1), and therefore the sediment transport capacity, were low. Consequently, ～60 % of the eroded sediment was deposited along the landscape, regardless of the spatial scale. The existing high-density reservoir network (contributing area of 6 km² per reservoir) also limits sediment propagation, retaining up to 47 % of the sediment at the large basin scale. The sediment delivery ratio (SDR) decreased with the spatial scale; on average, 41 % of the eroded sediment was yielded from the hillslopes, while for the whole 24,600-km² basin, the SDR was reduced to 1 % downstream of a large reservoir (1940-hm³ capacity).

Conclusions

Hydrological behaviour in the Upper Jaguaribe Basin represents a constraint on sediment propagation; low runoff depth is the main feature breaking sediment connectivity, which limits sediment transference from the hillslopes to the drainage system. Surface reservoirs are also important barriers, but their relative importance to sediment retention increases with scale, since larger contributing areas are more suitable for the construction of dams due to higher hydrological potential.     

Fishery indicators during a predictable aggregation of Atlantic sharpnose sharks Rhizoprionodon terraenovae in the southern Gulf of Mexico: An alternative to assess a heterogeneous data‐poor fishery

Small‐scale fisheries in the southern Gulf of Mexico that catch Rhizoprionodon terraenovae (Richardson) are heterogeneous and data‐poor. Fishery‐dependent monitoring was conducted from 2010 to 2017, including a target season during an aggregation of this species to estimate data‐poor fishery indicators. During the target season, the average sizes for females and males (95.3 and 89.8 cm total length, respectively) were recorded, a global male sex bias (1:1.7), the highest percentage of mature sharks for all years (>89%), the highest values of CPUE (20.1 sharks/day) and size‐selectivity higher than the size at maturity. The spawning potential ratio was over 0.6 (reference point of 0.71) in the combined (target and non‐target) and target seasons for all years, which suggests that the fishery stock is not healthy. Annual assessment of this fishery can be carried out through monitoring during the target season, where management is more feasible to implement.     

The number of leaves required for floral induction and translocation of the florigenic promoter in mango (Mangifera indica L.) in a tropical climate

Mango flowering appears to be determined by a temperature-regulated florigenic promoter (FP) synthesized in leaves and translocated to buds in phloem. The number of leaves required for flowering was investigated in ‘Keitt’ and ‘Tommy Atkins’ mango trees exposed to tropical conditions in Colombia. Data were compared with a previous study conducted under cool, floral-inductive conditions in Florida (Davenport et al., 2006). Leaf-number treatments consisted of 0, 1/8, 1/4, 1/2, 1, 2, 3, or 4 leaves on each of 20–40 stems per branch. The long distance translocation experiment consisted of a terminal donor stem and five defoliated receiver stems on each treatment branch. Treatments were 0, 1, 3, or 5 leaves on the donor stem. Every treatment branch in both experiments was girdled to isolate it from the rest of the tree, and developing panicles were removed to stimulate lateral shoot initiation at a time when conditions were right for floral induction in those buds. Treatment stems bearing no leaves produced only vegetative shoots in both cultivars in both experiments. The minimum number of leaves per stem (1/8 of a leaf and 1/4 of a leaf) was sufficient to induce 6% and 1% reproductive shoots with 94% and 99% vegetative shoots in Tommy Atkins’ and ‘Keitt’ stems, respectively. Branches bearing 4 leaves per stem in ‘Tommy Atkins’ trees produced the maximum mean flowering response with 45% reproductive shoots and 55% vegetative shoots. The maximum ‘Keitt’ response was 22% reproductive and 78% vegetative shoots with 4 leaves per stem. The donor stem of the 1-leaf treatment and the donor and first receiver stem of the 3-leaf treatment in the translocation experiment were induced to flower in ‘Tommy Atkins’ trees. The more distal receiver stems from the donor were vegetative. The 5-leaf donor treatment-induced reproductive shoots as far as the third leafless receiver stem located 52 cm from the donor. Proportions of flowering shoots decreased with distance from the donor, and the level of the FP was apparently insufficient to reach the fourth and fifth receivers since their shoot responses were vegetative. Only vegetative shoot responses were obtained in the translocation experiment conducted in ‘Keitt’ trees. The leaf number and translocation experiment results support the hypothesis that far less FP is synthesized in both ‘Tommy Atkins’ and ‘Keitt’ leaves during warm, tropical conditions than is synthesized in ‘Keitt’ leaves exposed to cool, subtropical conditions.     

Production and characterization of fibroin hydrogel using waste silk fibers

The use of natural resources, especially processing wastes, as low cost and environmentally friendly alternative aiming high value-added applications is a subject of broad interest. Since the Brazilian silk production annually generates a large amount of waste during the silk fibers processing, this work explores the preparation and characterization of silk fibroin hydrogels using spinning waste silk fibers from textile processing and the processed ones. Hydrogels were obtained directly by dialyzing silk fibroin solutions against frequent changes of water until the gelation point and then lyophilized and characterized in terms of their morphology, crystallinity, thermal resistance and secondary structure. X-ray diffraction analysis revealed the presence of β-sheet conformation related to sol-gel transition. FT-IR spectra indicated the coexistence of random coil (silk I) and β-sheet (silk II) structures, with predominance of β-sheet conformation for hydrogels from processed silk fibers. From thermogravimetric analysis the presence of β-sheet secondary conformation was demonstrated by a degradation peak around 292 °C for both hydrogels. Freeze-dried hydrogels presented sheet or leaf like morphology and no significant change was observed among the hydrogels from waste silk fibers and processed ones. These characteristics suggest that silk fibroin hydrogels prepared from spinning waste silk fibers and obtained directly by dialysis can be potential candidates for biomaterials application, such as drug delivery systems and for wound dressings.     

Isolation and identification of phase II enzyme inductors obtained from black Shawaya sorghum [Sorghum bicolor (L.) Moench] bran

The antioxidant capacity as oxygen radical absorbance capacity (ORAC) and in vitro chemopreventive effect of phytochemicals extracted, partitioned and isolated from the decorticated bran of black Shawaya sorghum (Sorghum bicolor L. Moench) was studied. The chemopreventive effect was evaluated as the induction effect of quinone reductase (QR) using murine hepatoma cells Hepa 1c1c7. The crude methanol extract with an antioxidant capacity of 3.7 μmol Trolox equivalent (TE)/mg was partitioned into 120 fractions with fast centrifugal partition chromatography (FCPC). Fractions with partition coefficients between 0.1 and 0.26 exerted more than 50% of the antioxidant activity of the original crude extract and contained the highest concentration of anthocyanins. No correlation was found for ferulic acid content and ORAC or chemoprevention. A derivative of 7-methoxyapigeninidin at a concentration of 1 μg/ml increased by 31% the QR activity while the original extract reached a maximum of 27% at 40 μg/ml.