Biomedical subjects

J A Meador

Publications and source records attributed to J A Meador.

3 recordsLinked to original sources

PubMed2000

AFLP Analysis Confirms Exclusive Maternal Genomic Contribution of Meiogynogenetic Sea Bass (Dicentrarchus labrax L.).

Meiogynogenesis was induced in the European sea bass Dicentrarchus labrax L. by fertilizing eggs with UV-irradiated sperm followed by inhibition of the second meiotic division by a cold shock. Putative gynogenetic progeny derived from three groups of breeders were analyzed for maternal inheritance using amplified fragment length polymorphism (AFLP) markers. Discrimination of fingerprints was based on male-specific bands, which were absent in females. Four of 64 MseI/EcoRI primer pairs used to analyze parental polymerase chain reaction products were selected to screen progeny for paternal AFLP markers in each group. Four to 11 diagnostic bands per fish confirmed the gynogenetic origin of the progeny. AFLP analysis determined that 89.5%, 100%, and 100% of the sea bass from groups 1, 2, and 3, respectively, were gynogenetic. Our results show that AFLP analysis is suitable for verification of gynogenesis in fish.

Journal Article↗

PubMed2000

Induction, distribution and repair of UV photodamage in the platyfish, Xiphophorus signum.

The genus Xiphophorus is an important model for investigating the etiology and genetics of sunlight-induced melanoma as well as other cancers. We used immunological techniques to determine the induction, distribution and repair of cyclobutane pyrimidine dimers (CPD) and pyrimidine(6-4)pyrimidone dimers ([6-4]PD) in different tissues of Xiphophorus signum exposed to ultraviolet-B light. We found that the (6-4)PD was induced at 5 to 10-fold lower frequency than the CPD and that scalation provided considerable photoprotection against both photoproducts. Photoenzymatic repair (PER) was very efficient in X. signum with most of the lesions removed within 20 min; PER of CPD occurred at about twice the rate of (6-4)PD. Nucleotide excision repair (NER) was much less efficient than PER and the rates of CPD and (6-4)PD removal were comparable. PER was more efficient in the caudal fin compared to the lateral epidermis; the opposite was true for NER. Although the initial rate of CPD excision was five-fold faster in the lateral epidermis compared to the caudal fin a considerable amount of residual damage remained in both tissues. The diverse photochemical and photobiological responses observed in X. signum suggest that heritable traits governing deoxyribonucleic acid damage induction and repair may be involved in the susceptibility of other Xiphophorus species to melanomagenesis.

Animals↗

PubMed1995

Cerumen impaction in the elderly.

1. Cerumen impaction is a reversible cause of conduction hearing loss in the elderly. 2. Risk factors include ear canal hairs, hearing aids, bony growths secondary to osteophyte or osteoma, and a history of impacted cerumen. 3. Cerumen removal can cause damage to the external auditory meatus, perforation of the tympanic membrane, and/or otitis media. 4. Methods to remove cerumen impactions include: ceruminolytic agents, curette methods and lavage method.

Aged↗