Maldronksiekte in cattle: a neuronopathy caused by Solanum kwebense N.E. Br.

A neurological disease of cattle (maldronksiekte), occurring in a localized area of the Northern Transvaal, was experimentally reproduced by feeding Solanum kwebense plants to cattle. The disease is characterized by temporary loss of balance and transient epileptiform seizures precipitated by a variety of stimuli, such as exercise, handling (dipping, loading, etc) and fright. When not disturbed, most affected animals appear to be completely normal. The most conspicuous histopathological lesion is a neuronopathy manifested by vacuolar degeneration and eventual necrosis of neurones, particularly of the Purkinje cells in the cerebellum. An atrophy of the cerebellar cortex is seen grossly. The history, clinical signs and experimental reproduction of the disease, as well as the pathology of 4 experimental and 18 natural cases, are described.     

Emergency avian surgery.

Avian surgery is an exercise of preparedness; this statement is never so true as in emergency and critical care situations. The techniques used in avian surgery are significantly different from those used in larger species and require microsurgical techniques. Before initiating a surgical procedure, the patient must be evaluated and, in many cases, prepared or preconditioned. Rarely is surgery such an emergency that the prognosis would not be improved by readying the patient. Techniques of tissue handling, approaches to the coelomic cavities and a select number of surgical procedures are described.     

Taxon-specific responses of soil bacteria to the addition of low level C inputs

The addition of small or trace amounts of carbon to soils can result in the release of 2-5 times more C as CO₂ than was added in the original solution. The identity of the microorganisms responsible for these so-called trigger effects remains largely unknown. This paper reports on the response of individual bacterial taxa to the addition of a range of ¹⁴C-glucose concentrations (150, 50 and 15 and 0 μg C g⁻¹ soil) similar to the low levels of labile C found in soil. Taxon-specific responses were identified using a modification of the stable isotope probing (SIP) protocol and the recovery of [¹⁴C] labelled ribosomal RNA using equilibrium density gradient centrifugation. This provided good resolution of the ‘heavy’ fractions ([¹⁴C] labelled RNA) from the ‘light’ fractions ([¹²C] unlabelled RNA). The extent of the separation was verified using autoradiography. The addition of [¹⁴C] glucose at all concentrations was characterised by changes in the relative intensity of particular bands. Canonical correspondence analysis (CCA) showed that the rRNA response in both the ‘heavy’ and ‘light’ fractions differed according to the concentration of glucose added but was most pronounced in soils amended with 150 μg C g⁻¹ soil. In the ‘heavy RNA’ fractions there was a clear separation between soils amended with 150 μg C g⁻¹ soil and those receiving 50 and 15 μg C g⁻¹ soil indicating that at low C inputs the microbial community response is quite distinct from that seen at higher concentrations. To investigate these differences further, bands that changed in relative intensity following amendment were excised from the DGGE gels, reamplified and sequenced. Sequence analysis identified 8 taxa that responded to glucose amendment (Bacillus, Pseudomonas, Burkholderia, Bradyrhizobium, Actinobacteria, Nitrosomonas, Acidobacteria and an uncultured β-proteobacteria). These results show that radioisotope probing (RNA-RIP) can be used successfully to study the fate of labile C substrates, such as glucose, in soil.     

Quantitative analysis and QTL mapping for agronomic and fiber traits in an RI population of upland cotton

Genetic mapping is an essential tool for cotton (Gossypium hirsutum L.) molecular breeding and application of DNA markers for cotton improvement. In this present study, we evaluated an RI population including 188 RI lines developed from 94 F₂-derived families and their two parental lines, ‘HS 46’ and ‘MARCABUCAG8US-1-88’, at Mississippi State, MS, for two years. Fourteen agronomic and fiber traits were measured. One hundred forty one (141) polymorphic SSR markers were screened for this population and 125 markers were used to construct a linkage map. Twenty six linkage groups were constructed, covering 125 SSR loci and 965 cM of overall map distance. Twenty four linkage groups (115 SSR loci) were assigned to specific chromosomes. Quantitative genetic analysis showed that the genotypic effects accounted for more than 20% of the phenotypic variation for all traits except fiber perimeter (18%). Fifty six QTLs (LOD > 3.0) associated with 14 agronomic and fiber traits were located on 17 chromosomes. One QTL associated with fiber elongation was located on linkage group LGU01. Nine chromosomes in sub-A genome harbored 27 QTLs with 10 associated with agronomic traits and 17 with fiber traits. Eight chromosomes in D sub-genome harbored 29 QTLs with 13 associated with agronomic traits and 16 with fiber traits. Chromosomes 3, 5, 12, 13, 14, 16, 20, and 26 harbor important QTLs for both yield and fiber quality compared to other chromosomes. Since this RI population was developed from an intraspecific cross within upland cotton, these QTLs should be useful for marker assisted selection for improving breeding efficiency in cotton line development. Paper number J1116 of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State University, Mississippi State, MS 39762. Mention of trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by USDA, ARS and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

An epizootic of blindness and encephalitis associated with a herpesvirus indistinguishable from equine herpesvirus I in a herd of alpacas and llamas

Blindness characterized by dilated unresponsive pupils and funduscopic evidence of varying degrees of vitritis, retinal vasculitis, retinitis, chorioretinitis, and optic neuritis developed in 21 alpacas and 1 llama within a 30-day period. The animals were part of a group of approximately 100 animals imported from Chile one year earlier. The animals had spent 6 months in quarantine and then, for the 6 months preceding the epizootic, were housed at an exotic animal import-export farm, where the disease developed. Four of the affected animals also had signs of neurologic dysfunction. A herpesvirus indistinguishable from equine herpesvirus I was isolated from 4 of the affected animals, and antibody titers diagnostic for equine herpesvirus I were demonstrated in the serum of all but one of the affected animals.