One-step RT-PCR for the Detection of Infectious Bursal Disease Virus in Clinical Samples

A single-tube, non-interrupted, one-step RT-PCR has been standardized to amplify the hypervariable region of the VP2 gene sequence of infectious bursal disease virus (IBDV). The technique standardized on purified viral RNA was successfully applied to the detection of the virus directly in clinical samples. The amplified products were confirmed to be IBDV specific by their size in ethidium bromide-stained agarose gel, nested PCR and restriction enzyme digestion. Digestion of the amplicons with StyI restriction enzyme also differentiated classical virus from six very virulent field isolates. The sensitivity of the one-step RT-PCR was found to be 0.2 pg of viral RNA.     

Evapotranspiration losses for pepper under plastic mulch and shallow water table conditions

Use of literature crop coefficient (K _c) values for quantifying evapotranspiration (ET_c) under non-standard conditions such as plastic mulch, shallow water table, and sub-tropical conditions can lead to inaccurate ET_c estimates. A 5-year experiment was conducted for fall crop growing seasons in south Florida to quantity bi-weekly ET_c and K _c for bell pepper grown under shallow water table and plastic mulch environments using large drainage lysimeters. The ET_c values varied from 205 to 320 mm with a seasonal average of 267 mm. Average K _c values for bell pepper for development, mid-season, and late stages were 1.05, 1.21, and 1.28, respectively. Higher than literature initial K _c values were due to rainfall and use of sub-irrigation system to maintain artificially high water table which results in high soil moisture in the bare soil area—such high moisture results in high evaporation. The K _c values from this study were statistically higher than literature values. Use of literature K _c values resulted in underestimating ET_c by 27–37%. The K _c values would provide improved estimates of sub-irrigated pepper ET_c in subtropical Florida and elsewhere with similar environment.     

The Fusarium graminearum genome reveals a link between localized polymorphism and pathogen specialization

We sequenced and annotated the genome of the filamentous fungus Fusarium graminearum, a major pathogen of cultivated cereals. Very few repetitive sequences were detected, and the process of repeat-induced point mutation, in which duplicated sequences are subject to extensive mutation, may partially account for the reduced repeat content and apparent low number of paralogous (ancestrally duplicated) genes. A second strain of F. graminearum contained more than 10,000 single-nucleotide polymorphisms, which were frequently located near telomeres and within other discrete chromosomal segments. Many highly polymorphic regions contained sets of genes implicated in plant-fungus interactions and were unusually divergent, with higher rates of recombination. These regions of genome innovation may result from selection due to interactions of F. graminearum with its plant hosts.     

Development of two cell culture systems from Asian seabass Lates calcarifer (Bloch)

Two new cell culture systems namely epitheloid cells of Lates (LCE) and fibroblastic cells of Lates (LCF) have been developed from fry and fingerling of the economically important brackishwater fish Lates calcarifer. Primary cultures were initiated by explant technique using caudal fin of fingerling and whole body tissue of the fry. The nutritional requirements and the growth pattern in response to different culture environment were similar for the two cell cultures. The culture medium used was Leibovitz‐15 supplemented with 20% fetal bovine serum (FBS) and 1% fish serum. The LCE comprised of epithelioid cells and LCF cells were fibroblastic. With a split ratio of 1:2, the confluency of cells was attained in 8–10 days at an incubation temperature of 28°C. The cells were found to grow well in a wide range of temperature (24–32°C) and stable at 20 and 36°C. The growth rate of LCF and LCE cells increased proportionately with the concentration of FBS from 5% to 20%. A decrease of serum level to 10% after eight subcultures produced no apparent change in cell morphology and growth rate. The viability of cells was found to be 70% when revived after a month of storage in liquid nitrogen (?196°C).     

Linking winter and summer events in a migratory bird by using stable-carbon isotopes

For migratory birds, early arrival and physical condition on the breeding grounds are important determinants of reproductive success and fitness. Differences in arrival times often exceed a month, and later arriving individuals are often in poorer condition. Habitat-specific isotopic signatures indicate that the quality of winter habitats occupied by American redstarts (Setophaga ruticilla) determines their physical condition and spring departure dates, which in turn result in variable arrival schedules and condition on temperate breeding grounds. These findings link events in tropical winter grounds with those in temperate breeding areas for a migratory songbird and provide evidence that winter habitats may be limiting.     

Pruned tea bushes secrete more root exudates to influence microbiological properties in soil

Pruning is adopted at 3–4 years interval as an agronomic practice during tea cultivation. It was hypothesized that biomass loss during pruning will imply stress on tea bushes. The aim of this study was to quantify changes in different parameters (labile organic carbon fractions, phosphatase activity, microbial biomass and microbial respiration) in tea rhizosphere due to pruning by collecting soil samples from the rhizosphere of ten of each pruned and un-pruned tea bushes. Hot-water extractable and dissolved organic C contents in rhizosphere soil of pruned tea were significantly (P ≤ 0.05) higher than those in the soil of un-pruned tea bushes. Analysis of phospholipid fatty acids (PLFA) revealed that the rhizosphere of pruned tea plants had higher population of Gram (+) and Gram (-) bacteria, fungi, actinomycetes and lower denitrifying bacterial population as compared to un-pruned tea plants. Activity of acid phosphatase enzyme in soil was also increased due to pruning. A separate study revealed that de-centering may induce production of up to 50% more labile organic carbon compounds by young tea as compared to un-pruned plants. Therefore, it could be concluded that pruned tea bushes secrete more root exudates to influence microbiological and biochemical properties in rhizosphere.