Abstract
Abstract: :
Purpose: We looked for differences in mRNA expression between male and female rabbit lacrimal glands. Methods: Poly(A)+ RNA was isolated from male and female New Zealand rabbit lacrimal glands, reverse transcribed, and the resultant cDNAs were PCR-amplified with defined sets of primers for differential display analysis. A 150 base, male-specific product was identified and RACE-PCR was used to obtain the full length sequence. Poly(A)+ RNAs from rabbit tissues were electrophoresed in an agarose gel and transferred to nylon. The male-specific differential display fragment, representing the 3' 150 bases of the molecule, was labeled with 32P and hybridized to the RNA blot. Results: A small 450 base mRNA, which we identified only in male rabbit lacrimal glands, encoded a new sequence. BLAST data base comparisons of this sequence indicated that it was a secretory lipophilin (uteroglobin family), which we named lipophilin AL2 (GenBank accession # AY063770). The full length cDNA sequence of lipophilin AL2 is 464 bases. The longest open reading frame predicts a product of 96 amino acids, which is 50% identical to rabbit submaxillary gland lipophilin AS (GenBank accession # AF308615). By analogy with rabbit (and human) lipophilins, lipophilin AL2 likely contains a cleaved leader sequence, resulting in secretion of the protein in tears. Northern blot analysis confirmed the male-specific expression of lipophilin AL2 in rabbit lacrimal glands. A 32P-labeled fragment of lipophilin AL2 hybridized strongly to a 0.5 kb message (and weakly to a 1.8 kb band) in male rabbit lacrimal glands. Male rabbit heart also contained a faint 1.3 kb band. However we observed no hybridization signal in female rabbit lacrimal glands, male or female rabbit harderian glands, male liver or male pancreas. Conclusion: A male-specific mRNA predicted a new protein, lipophilin AL2, expressed in male rabbit lacrimal glands and likely secreted in tears.
Keywords: 452 lacrimal gland • 417 gene/expression • 476 molecular biology