Ocular anomalies in a herd of Exmoor ponies in Canada.

OBJECTIVE: To characterize the ocular anomalies, determine their recurrence in families and assess the mode of inheritance of the most prevalent anomalies through pedigree analysis in a herd of Exmoor ponies. ANIMALS STUDIED: Thirty Exmoor ponies residing in south-western Ontario, Canada. PROCEDURES: Ophthalmic examination was performed using direct ophthalmoscopy, slit-lamp biomicroscopy and indirect ophthalmoscopy, pre- and post-pupillary dilation. Following compilation of ocular findings, pedigree analysis was conducted to assess the recurrence pattern of specific anomalies in families and the data were tested for significance for breed prevalence and gender dependence, using Fisher's exact test. RESULTS: Twenty-eight purebred ponies and two cross-breds, ranging from 14 days to 31 years were examined. A prominent brow above the eyes characteristic of this breed was a consistent periocular feature of adult ponies. In nine ponies, eyelid sarcoid, iris nevus, Mittendorf's dot, hyaloid artery remnant, and hyper-reflective vitreal strands were detected while the lesions recorded in the remaining 21 included macroblepharon, persistent pupillary membranes, iris hypoplasia, cataracts, focal choroidal or retinal pigment epithelium hypoplasia and optic nerve head coloboma. The most common ocular finding was cataracts seen mainly in females. Statistical tests on prevalence data confirmed a significant breed and sex association. Pedigree analysis favored a sex-linked mode of inheritance for cataracts in this line of Exmoor ponies. CONCLUSIONS: Although the ocular anomalies detected in this group have been previously reported in other breeds of horses, this is the first report of equine cataracts showing a familial trend suggestive of a sex-linked genetic defect.

Cytogenetic evaluation of human oocytes that failed to complete meiotic maturation in vitro.

OBJECTIVE: To determine the cause of infertility in a couple whose oocytes failed to mature in two consecutive fertility treatments. DESIGN: Case report. SETTING: University-based IVF program. PATIENT(S): A 32-year-old woman with unexplained infertility. INTERVENTION(S): Cytogenetic evaluation of oocytes that failed to reach meiotic metaphase II stage of maturation. MAIN OUTCOME MEASURE(S): Observation of oocyte maturity and chromosome composition after fixing and staining with Orcein stain. RESULT(S): Cytogenetic analysis revealed that the oocytes had successfully resumed meiosis. Germinal vesicle breakdown was also indicated, and chromosomes were at metaphase II stage of development. However, meiotic reduction of those chromosomes failed. CONCLUSION(S): Infertility in this couple seems to be attributed to the failure of the chromosomes to complete the reduction phase of metaphase II of meiosis.

Expression in Pichia pastoris and characterization by circular dichroism and NMR of rhodostomin.

Rhodostomin (Rho) is a snake venom protein isolated from Calloselasma rhodostoma. Rho is a disintegrin that inhibits platelet aggregation by blocking the binding of fibrinogen to the integrin alpha(IIb)beta3 of platelets. Rho produced in Escherichia coli inhibited platelet aggregation with a K(I) value of 263 nM. Although functional, Rho produced in E. coli is misfolded based on our 2D and 3D NMR studies. In order to correct the folding problem, Rho was expressed in Pichia pastoris. The recombinant Rho expressed in P. pastoris inhibited platelet aggregation with a resulting K(I) value of 70 nM. This is the same potency as that of native Rho. CD analysis showed that the secondary structures of Rho are pH-independent and contain 3.5-7.9% alpha-helix, 48.2-50.5% beta-structures, and 42.3-47% coil. The sequential assignment and structure analysis of Rho were obtained using 2D and 3D 15N-edited NMR spectra. These results provide the first direct evidence that highly disulfide-bonded disintegrin can be expressed in P. pastoris with the correct fold. This evidence may serve as the basis for exploring the structure and function relationships as well as the dynamics of disintegrin and its variants.

beta-carbolines that accumulate in human tissues may serve a protective role against oxidative stress.

beta-Carbolines are tricyclic nitrogen heterocycles formed in plants and animals as Maillard reaction products between amino acids and reducing sugars or aldehydes. They are being detected increasingly in human tissues, and their physiological roles need to be understood. Two beta-carboline carboxylates have been reported to accumulate in the human eye lens. We report here on the identification of another beta-carboline, namely 1-methyl-1-vinyl -2, 3,4-trihydro-beta-carboline-3-carboxylic acid, in the lenses of some cataract patients from India. Analysis of these three lenticular beta-carbolines using photodynamic and antioxidant assays shows all of them to be inert as sensitizers and effective as antioxidants; they quench singlet oxygen, superoxide and hydroxyl radicals and inhibit the oxidative formation of higher molecular weight aggregates of the test protein, eye lens gamma-crystallin. Such antioxidative ability of beta-carbolines is of particular relevance to the lens, which faces continual photic and oxidative stress. The beta-carboline diacid IV is also seen to display an unexpected ability of inhibiting the thermal coagulation of gamma-crystallin and the dithiothreitol-induced precipitation of insulin. These results offer experimental support to earlier suggestions that one of the roles that the beta-carbolines have is to offer protection against oxidative stress to the human tissues where they accumulate.

A Novel Insect Antifeedant Nonprotein Amino Acid from Calotropis gigantea

Giganticine (1), a novel nonprotein amino acid, has been isolated from a methanol extract of the root bark of Calotropis gigantea and its structure established by spectroscopic methods. It exhibited a significant antifeedant activity against nymphs of the desert locust Schistocerca gregaria.