Physical, chemical, and serological characterization of avian rotaviruses

Physical, chemical, and serological characterization of rotavirus isolates from turkeys was done. Cesium chloride (CsCl)-gradient isopycnic centrifugation of infected cell cultures revealed the presence of rotavirus particles of three different densities. They were double-shelled, single-shelled, and core particles. The double-shelled particles had a buoyant density (in CsCl) of 1.34 g/cml3, and that of single-shelled particles in CsCl was 1.36 g/cm3. The buoyant density of core particles in CsCl was greater than 1.40 g/cm3. These rotavirus isolates were not inactivated by chloroform and were relatively stable at pH 3.0. Their replication was not affected by 5-bromo-2'-deoxyuridine. Avian rotaviruses were not completely inactivated by heat treatment of 56 C for 8 hr. All six avian rotavirus isolates examined were antigenically related to each other. However, there was no antigenic relationship between mammalian rotaviruses and the avian rotavirus isolates examined.     

Two single nucleotide polymorphisms in the promoter of the ovine myostatin gene (MSTN) and their effect on growth and carcass muscle traits in New Zealand Romney sheep

Myostatin is a negative regulator of muscle growth and development in mammals, and variation in ovine myostatin gene (MSTN) has been demonstrated to be associated with variation in the muscularity of sheep. Polymerase chain reaction–single‐stranded conformational polymorphism (PCR–SSCP) was used to look for single nucleotide polymorphisms (SNPs) in a 304‐bp amplicon from the promoter region of ovine MSTN. Sequence analyses revealed two previously identified SNPs (c.?2449G/C and c. ?2379T/C) that resulted in three haplotypes (H₁ (c.[?2449G; ?2379C]), H₂ (c.[?2449C; ?2379C]) and H₃ (c.[?2449G; ?2379T]). The effect of these SNPs on growth and carcass traits was investigated in 357 NZ Romney lambs. General linear mixed‐effect models revealed that sheep with the genotype c.?2449GC had a higher loin meat yield (p = 0.032) and proportion loin yield (p = 0.028), than those with the genotype c.?2449GG. The genotype c.?2379CC was associated with an increase in three weight traits: birthweight (p = 0.003), tailing weight (p = 0.009) and weaning weight (p = 0.028), when compared with the genotype c.?2379TC, but it was not found to have an association with growth rate. This suggests that c.?2379T/C has an effect that originates at, or before birth. Haplotype H₃ was associated with a decrease in birthweight (p = 0.002), tailing weight (p = 0.003) and weaning weight (p = 0.011). Haplotype H₂ was associated with increased loin yield (p = 0.012) and proportion loin yield (p = 0.002). The SNPs may have value as genetic markers for improved Romney breeding.     

Genotypic Differences in Root Hair Deformation and Subsequent Nodulation for Red Clover under Different Additions of Starter N Fertilization

Red clover cultivars, including diploid and tetraploid, are commonly used in legume‐based pasture mixtures. However, information on nodulation under different starter N regimens is limited. We hypothesized that there is genetic variability among different red clover cultivars for nodulation. A root hair deformation assay was conducted using three diploid (AC Christie, Tapani and CRS15) and three tetraploid (Tempus, CRS18 and CRS39) red clover cultivars by inoculating them with Rhizobium leguminosarum biovar trifolii. Nodulation and morphological characteristics of two selected red clover cultivars, AC Christie and Tempus, were determined under five starter N concentrations (0, 0.2, 0.4, 0.8 and 1.6 mg per plant). Inoculation with rhizobia increased root hair deformation with significant interaction across cultivars. Nodulation was delayed under high starter N concentrations, and genotypic differences were evident for days‐to‐nodule initiation. There was a positive quadratic response to starter N for AC Christie and a negative quadratic response for Tempus for nodulation. Tempus had more active nodules (92 %) than AC Christie (73 %). The genetic variability of red clover cultivars should be considered in N fixation studies and their response to availability of initial N.     

Cytological and genetical studies of a male sterile celery

Summary The inheritance and nature fo male sterility of a cerley (Apium graveolens L.) strain (MS1) is reported. Male sterility in MS1 is determined by a a recessive genotype for a single locus. Tests for linkage with the isozyme chromosome markers SDH-1 and PGM-1 were negative. MS1 male sterility was associated with a defective tapetum characterized by prominent vacuoles and premature degeneration. The stamens in the male sterile strain persisted in the flowers up to stigma receptivity, while in the male fertile plants they dropped before style expansion. The male sterile flowers produced normal amounts of nectar, resulting in cross pollination by various species of pollinators. It was estimated that the sterile strain produced 30% less seed than normal male fertile. Its possible use for hybrid celery seed production is discussed.Research supported by grants from the California Celery Research Board and BARD I-483-82.     

Enigmatic hotspot of crayfish diversity at risk: Invasive potential of non‐indigenous crayfish if introduced to New Guinea

1. The large island of New Guinea has a rich indigenous astacofauna represented by numerous parastacids from the genus Cherax. The western half of the island is part of Indonesian territory.
2. Indonesia is known to be the main exporter of ornamental crayfish globally, and certain New Guinean species are exploited as ornamentals within the international pet trade. Moreover, one non‐indigenous species has been previously recorded being cultured in Java, Indonesia. This species, the North American Procambarus clarkii, is a vector of crayfish plague, the disease that is lethal to most parastacids. This population has already tested positive for the disease.
3. As the transport of non‐indigenous crayfish within the Indonesian territory is not restricted, their introduction to New Guinea can be expected. The Indonesian market was therefore surveyed for ornamental crayfish and their environmental suitability evaluated, as represented by temperature during the drought and rainy seasons in New Guinea.
4. Four North American and one Australian species were found advertised for sale. One of them, P. clarkii, was assessed as the most damaging species, followed by other North American species. A total ban on the culture and transport of the highest risk crayfish species in Indonesia and Papua New Guinea is recommended.

     

Cascading effects of introduced Nile perch (Lates niloticus) on the foraging ecology of Nile tilapia (Oreochromis niloticus)

Abstract –  Nile tilapia ( Oreochromis niloticus L.) is the dominant of the introduced tilapiines in many East African lakes and has flourished in the presence of introduced Nile perch ( Lates niloticus L.). We explored the hypothesis that O. niloticus exhibits increased omnivory in response to a decline in abundance of haplochromine cichlids. First, we quantified variation in habitat use and diet of O. niloticus in Lake Nabugabo, Uganda. Second, we compared the diet of O. niloticus in lakes with (Nabugabo, Victoria) and without (Mburo, Wamala, Nyamusingiri, Kyasanduka) introduced Nile perch. In Lake Nabugabo, a higher level of phytoplanktivory was observed in small juveniles than in larger fish and in wetland ecotone areas where haplochromines were most abundant. An omnivorous diet dominated by detritus and invertebrates was recorded for O. niloticus in lakes Nabugabo and Victoria, while a predominantly herbivorous diet was characteristic of O. niloticus in lakes without Nile perch. Availability of a broad food base in lakes where inshore insectivores have been reduced may explain the increased omnivory recorded in lakes Nabugabo and Victoria.     

Sensitivity of Two Quinoa (ChenopodiumquinoaWilld.) Varieties to Progressive Drought Stress

Quinoa (ChenopodiumquinoaWilld.) is a highly nutritious Andean seed crop which shows great potential to grow under a range of hostile environments. The objective of this study was to investigate the differences of drought tolerance of a Bolivian (Achachino) and a Danish (Titicaca) variety, and especially drought‐related adaption strategies. Soil water status was expressed as the fraction of transpirable soil water (FTSW). Relative stomatal conductance (RSC), relative transpiration (RT) and relative leaf water potential (RLW) were calculated by determining stomatal conductance, transpiration rate and leaf water potential of the drought‐treated plants relative to those of fully irrigated plants. The responses of RSC, RT and RLW to decreasing FTSW were described by a linear‐plateau model. The critical value of FTSW was the threshold of FTSW where the parameters studied decreased. The thresholds increased C_S for stomatal conductance, C_T for transpiration and C_Lfor leaf water potential. Achachino showed significantly lower C_T and C_L when compared with Titicaca, implying that transpiration and leaf water potential were less affected under mild drought conditions in the Bolivian variety. C_S in Achachino was significantly higher than C_L and C_T, which indicated that stomatal conductance declined before transpiration and leaf water potential were reduced. Such difference was found in Titicaca where reduction of leaf area had more effect on transpiration than stomatal closure. Slower growth rate and smaller leaf area in combination with a lower stomatal conductance was found to contribute to drought resistance in Achachino. ABA concentration in the xylem sap tended to increase in both varieties after 2 days onset of drought, prior to decline in leaf water potential. Titicaca showed significantly (P < 0.05) higher ABA concentration when compared with Achachino under both fully irrigated and drought conditions. Titicaca had higher xylem nutrient concentration in comparison with Achachino in both fully‐watered and drought plants at day 2 after onset of soil drying. It was concluded that Titicaca was more sensitive to progressive drought than Achachino which avoided water loss by means of lower growth rate and smaller leaf area.     

Soil organic phosphorus fractions in response to long-term fertilization with composted manures under rice–wheat cropping system

Present investigation evaluates the effect of organic fertilization (OF), integrated nutrient management (INM) practice, and recommended dose of chemical fertilization (CF) on changes in soil organic phosphorus (P) and its fractions under rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system. The 4-year experiment (2009–2013), under split-plot design, showed that OF did not increase the total P or total organic P content of soil under either of the test crops. However, OF maintained the higher level of labile organic P and moderately labile organic P in soil under wheat the moderately stable organic P and highly stable organic P was highest in paddy soil under CF practices (11.34 and 7.77 μg g^?1, respectively) followed by wheat. The P concentration in organically grown rice or wheat grain was increased significantly compared with their CF counterparts. The productivity economics for rice and wheat crops showed INM fertilization to be more economical than OF.