Genetic nature of phosphorus accumulation in maize

The inheritance of phosphorus accumulation in the ear leaves of maize (Zea mays L.) was investigated. Five inbreds were chosen, two high phosphorus accumulators (Rg‐8 and G‐307), two low phosphorus accumulators (Rd‐2 and Rg‐5), and a moderate one (K‐64). Their parents were used to obtain all possible ten Fl hybrids (in one direction), 10 F2, 10 Bl, and 10 B2 segregational generations. Phosphorus was estimated at 50% tasseling date. Phosphorus accumulation in these genotypes was found to be genetically controlled and is affected by non ‐ allelic gene interaction in addition to the additive and dominance gene effects. The high phosphorus accumulating inbred parents proved to be the best general combiners and the (high x low) hybrids showed the best specific combining abilities. The estimates of the minimum number of segregating genes in the (high x low) crosses revealed the presence of at least 10 segregating factors; however, the possibility of genetic linkage was not rolled out.     

Evaluation of a cocktail of phages for the control of presumptive Vibrio parahaemolyticus strains associated to acute hepatopancreatic necrosis disease

Shrimp culture is a well‐established and fast‐growing industry that produces economic and social benefits in many countries. However, during the last years, it was severely affected by the emergence of the Early Mortality Syndrome (EMS) or Acute Hepatopancreatic Necrosis Disease (AHPND). This disease is mainly attributed to Vibrio parahaemolyticus, and currently, there is no effective cure or treatment. In this study, the use of T2A2 and VH5e bacteriophages was evaluated to control different AHPND‐positive strains (presumptively identified as V. parahaemolyticus, VP_AHPND) under laboratory conditions. Lytic effect of T2A2 and VH5e bacteriophages against different strains isolated from AHPND outbreaks was corroborated. In addition, the effectiveness of the mixture of both phages was tested on a brine shrimp experimental infection model using three highly virulent VP_AHPND strains. It has been found that phage‐treated brine shrimp had significantly higher survival percentage compared with non‐treated groups (p < .001). Also, phage cocktail was found to be harmless to the organisms. These results suggest that the phage mixture is worth considering as a possible control measure for positive AHPND strains, although it is clear that further and more extensive testing is needed.     

Appraisal of a high protein distiller’s dried grain (DDG) in diets for European sea bass,Dicentrarchus labrax fingerlings on growth performance,haematological status and related gut histology

High protein distiller's dried grains (HP‐DDG) are co‐products of ethanol production that uses prefractionation technology. An 8‐week growth trial was conducted to investigate the effect of partial replacement of soybean meal (SBM) by three levels of HP‐DDG (30%, 40% and 50%) on growth performance, physiological parameters and histological changes of the intestine of European sea bass, Dicentrarchus labrax. The results indicated that an increased dietary level of HP‐DDG of more than 30% significantly increases growth performance and improved the FCR of sea bass. In addition, replacement of SBM by HP‐DDG enhanced feed intake efficiency and the health status of fish. Haematology and serum biochemistry (haemoglobin (Hb), red blood cells (RBCs), white blood cells (WBCs), packed cell volume (PCV %) and humeral immune parameters including total protein, albumin, globulin, cholesterol, lysozyme activity and total antioxidant capacity significantly increased with increase HP‐DDG inclusion levels. The findings of this study indicated that HP‐DDG is a good complementary protein source for inclusion aquaculture diets and levels above 30% as a replacement of SBM did not compromise growth performance and physiological parameters of sea bass while enhancing some important indices of health status in this species.     

Quantitative analysis of an experimental white spot syndrome virus (WSSV) infection in Penaeus monodon Fabricius using competitive polymerase chain reaction

White spot syndrome virus (WSSV) has been a major pathogen of cultured Penaeus monodon Fabricius in Malaysia since 1994. As quantitative study on the replication of WSSV is in its infancy, competitive polymerase chain reaction (PCR) was used for quantitative study of an experimental WSSV infection per os in growout P. monodon . Gills, abdominal integument and abdominal muscle were selected for viral quantification. Infection was detectable as early as 14 h postinfection (h p.i.) in both gills and integument, but the infection in muscle was only detected at 24 h p.i. Gill tissue had the highest viral load, followed by integument and muscle. Typical viral growth curves were obtained for all organs with distinct phases of eclipse (0–24 h p.i.), logarithmic (24–48 h p.i.) and the plateau (48–120 h p.i.). Cumulative mortality rapidly increased from 48 h p.i. and reached 100% at the end of the plateau phase at 120 h p.i. Gross signs of white spots and reddish discoloration were also obvious in moribund individuals from the plateau phase. Based on the three phases of viral growth, WSSV infection was classified into light, moderate and heavy infection stages.     

Phenotypic plasticity in gene expression and physiological response in red drum <Emphasis Type="Italic">Sciaenops ocellatus</Emphasis> exposed to a long-term freshwater environment

Red drum (Sciaenops ocellatus) is a euryhaline fish commonly found in the Gulf of Mexico and along the Atlantic coast of North America. Because of high commercial demand and its euryhaline characteristics, aquaculture of this species has diversified from marine to low-salinity aquaculture systems. In recent years, interest in the feasibility of producing red drum in inland freshwater systems has grown and this prompted us to investigate its osmoregulatory capacity after rearing for 8 months in a freshwater aquaculture system. We compared the activities of several genes and enzymes involved in the osmoregulatory process in freshwater-acclimatized (FW) and seawater (SW) red drum. The gene expression profiles were variable: the expression of genes encoding Na⁺/K⁺-ATPase (NKA) and the cystic fibrosis transmembrane regulator (CFTR) was slightly higher in SW than FW fish, while phosphoenolpyruvate carboxykinase (PEPCK) and the glucocorticoid receptor messenger RNA (mRNA) levels were higher in FW red drum. The total plasma K concentration was 60.3% lower, and gill NKA activity was 63.5% lower in FW than in SW fish. PEPCK activity was twofold higher in FW than in SW red drum. Similarly, liver glycogen was 60% higher in FW fish. In summary, both gene expression and the enzyme activity data support the phenotypic plasticity of red drum and suggest that the limited capacity for ion homeostasis observed, in particular the low plasma K concentration, was due to the composition of freshwater and does not necessarily reflect a physiological inability to osmoregulate.     

Relationship of milled grain percentages and flowering-related traits in rice

The economic value of harvested rice is determined by the grain yield and the percentages of head rice (at least 3/4 the length of a head or kernel) and total milled rice. This study was conducted to determine the effects of flowering-related traits such as duration of flowering, rate of flowering, heading, and duration from heading to maturity on head rice and total milling percentages of rice. Flowering data, gathered for two years from 105 long grain rice genotypes grown in Beaumont, Texas were analyzed for their effects on and relationship with milling traits. A positive linear relationship was obtained for rate of flowering and the duration from heading to maturity but negative for duration of flowering and days to heading. Genotypes with early heading had relatively shorter flowering durations, and genotypes with shorter flowering duration had higher head rice and total milled rice. A faster rate in attaining 100% flowering and more days from heading to maturity were favorable in increasing head rice and total milled grains. The duration from the start of flowering to heading or to 100% flowering can be used in the evaluation and selection for high head rice and total milled rice percentages in rice.     

Isolation and detection of Fasciola hepatica DNA in Lymnaea viatrix from formalin-fixed and paraffin-embedded tissues through multiplex-PCR

Detection of Fasciola hepatica infection in Lymnaea viatrix through analysis of histological cuts is based upon morphological characters of the parasite during the intra-mollusk phase of parasitism. At this stage, trematode forms are very similar and, thus, very difficult to differentiate. Specific detection may also be impaired by the presence of other helminthes in the mollusk. Histological samples are usually fixed in formalin, embedded in paraffin, sectioned and HE stained. In the current study, a method for the extraction of DNA from formalin-fixed, paraffin-embedded tissues was standardized by means of deparaffinizing with xylol and digesting with proteinase K. Extracted DNA was amplified in a multiplex-PCR, by using simultaneous primers in a single reaction under high stringency conditions. Results showed specific amplification of DNA from the trematode and the snails. The technique was sensitive enough to detect F. hepatica infections in L. viatrix, in histological sections in which the presence of larval stages could not be observed through brightfield microscopy. The profiles generated were: stair bands referring to F. hepatica DNAmt amplification; a band of 1200 bp referring to L. viatrix ITS and another of 1300 bp referring to F. hepatica ITS and other trematodes. Multiplex-PCR has shown to be a fast, safe, highly sensitive and specific method, which is able to amplify DNA from fixed tissues, despite a low DNA quantity and its degradation caused by fixation processes. Such methodology may be useful in studies on fascioliasis epidemiology, enabling the use of material from histological collections.     

Antioxidant enzyme activities and immune responses in rainbow trout (Onchorhynchus mykiss) juveniles fed diets supplemented with dandelion (Taraxacum officinalis) and lichen (Usnea barbata) extracts

Fish Physiology and Biochemistry - In the present study, antioxidant activity, immune responses, and growth performance of rainbow trout (Onchorhynchus mykiss) juveniles fed with diets supplemented...