Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.10.3.1 (tyrosinase)
 9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The formation of the egg mass in the ootype, containing the oocyte, vitelline cells, numerous spermatozoa and Mehlis' gland secretion marks the beginning of eggshell formation. Mehlis' gland cells pour their lipoprotein secretion into the ootype; this secretion forms a thin template around the egg mass and upon this template the shell globules are deposited. Eggshell formation begins in the proximal uterus and is completed in the middle uterus. The eggshells are devoid of phenols and phenolase indicating that hardening is not by quinone tanning. The eggshells contain keratin and are stabilized by disulphide linkages.
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PMID:Histochemical studies on eggshell formation in Paramphistomum cervi (Digenea: Paramphistomatidae). 357 22

Proacrosin, the zymogen form of the serine protease acrosin, is located within the acrosomal vesicle of mammalian spermatozoa and has been suggested to be involved in the fertilization process. In mouse and rat, expression of the proacrosin gene starts in pachytene spermatocytes and continues through the early stages of spermiogenesis. We have shown recently that 2.3 kilobase pairs of the 5'-flanking region of the rat proacrosin gene is sufficient to direct chloramphenicol acetyltransferase gene expression in a germ cell-specific and developmental stage-specific manner in the mouse. Additional transgenic lines have been generated which include two deletions in the 5'-flanking region and a tyrosinase minigene as marker for gene expression. Transgenic mice bearing these two truncated fragments showed different patterns of reporter gene expression. Transgenic lines (BM, B3, B2) harboring the 397-base pair (bp) fragment (from 45 to 442 bp upstream of ATG) showed no chloramphenicol acetyltransferase (CAT) activity in either testis or other tissues, but analysis via reverse transcription polymerase chain reaction confirmed low levels of reporter gene transcription in testis. Transgenic line TC bearing a longer fragment of 877 bp (from 45 to 922 bp upstream of ATG) showed a reporter gene expression and chloramphenicol acetyltransferase enzyme activity which was identical to that found in mice harboring the 2.3-kilobase pair 5'-flanking region. The analysis of the CAT gene expression during testicular development showed diploid transcription and haploid translation. It can be concluded that all sequences required for a basic level of testis-specific transcription of transgene are present within the 397-bp fragment, and other DNA sequences located outside of the 397-bp fragment but present within the 877-bp fragment can function as enhancer elements. Two fragments within the 877-bp region were identified by gel retardation assays as binding exclusively to nuclear factor(s) from testis protein extracts. In both fragments we identified sequence elements which are present in the promoter region of the germ cell-specific genes for histone H2B and protamine 1, respectively.
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PMID:Functional and molecular characterization of the transcriptional regulatory region of the proacrosin gene. 779 16

The production of animals with large transgenes is an increasingly valuable tool in biotechnology and for genetic studies, including the characterization and manipulation of large genes and polygenic traits. In the present study, we describe an intracytoplasmic sperm injection (ICSI) method for the stable incorporation and phenotypic expression of large yeast artificial chromosomes (YAC) constructs of submegabase and megabase magnitude. By coinjecting spermatozoa and YACs into metaphase II oocytes, we were able to produce founders exhibiting germline transmission of an intact and functional transgene of 250 kilobases, carrying the mouse tyrosinase locus, used here as a reporter gene to rescue the albinism of recipient mice. More than 35% transgenesis was obtained for this YAC transgene. When compared with the pronuclear microinjection standard method, the efficiency of the ICSI-mediated YAC transfer system was significantly greater. In summary, we describe, for the first time, stable incorporation in the host genome and correct phenotypic expression of large DNA constructs mediated by ICSI.
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PMID:Efficient generation of transgenic mice with intact yeast artificial chromosomes by intracytoplasmic sperm injection. 1528 29