One of the most exciting revelations in retinal biology is the realization that the molecules and mechanisms that regulate eye development have been conserved in all seeing animals including such diverse organisms as the fruit fly, mouse and man. The emerging commonality among mechanisms used in eye development allows for the use of model systems such as the fruit fly, Drosophila melanogaster, to provide key insights into the development and diseases of the mammalian eye. Eye specification in Drosophila is controlled, in part, by the concerted activities of eight nuclear proteins and several signal transduction cascades that together form a tightly woven regulatory network. Loss of function mutations in several components lead to the complete derailment of eye development while ectopic expression of threse genes in non-retinal tissues can direct the fates of these tissues towards eye formation. Here we will describe what is currently known about this remarkable regulatory cassettee highlight some of the outstanding questions that still need to be answered.
{"title":"The Eye Specification Network in Drosophila.","authors":"Brandon P Weasner, Jason Anderson, Justin P Kumar","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>One of the most exciting revelations in retinal biology is the realization that the molecules and mechanisms that regulate eye development have been conserved in all seeing animals including such diverse organisms as the fruit fly, mouse and man. The emerging commonality among mechanisms used in eye development allows for the use of model systems such as the fruit fly, Drosophila melanogaster, to provide key insights into the development and diseases of the mammalian eye. Eye specification in Drosophila is controlled, in part, by the concerted activities of eight nuclear proteins and several signal transduction cascades that together form a tightly woven regulatory network. Loss of function mutations in several components lead to the complete derailment of eye development while ectopic expression of threse genes in non-retinal tissues can direct the fates of these tissues towards eye formation. Here we will describe what is currently known about this remarkable regulatory cassettee highlight some of the outstanding questions that still need to be answered.</p>","PeriodicalId":90692,"journal":{"name":"Proceedings of the Indian National Science Academy. Part B, Biological sciences","volume":"B70 5-6","pages":"517-530"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4286332/pdf/nihms-126184.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32967621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
THE CLASTOGENICITY OF THE DIETARY CONCENTRATION OF CRUDE AFLATOXIN (MAINLY B1 AND UNDETECTABLE AMOUNT OF B2, G1 AND G2), HITHERTO WELL-KNOWN IN MITOTICALLY DIVIDING CELLS, WAS TESTED IN METAPHASE-I CHROMOSOMES OF PRIMARY SPERMATOCYTES OF ALBINO SWISS MICE, MUS MUSCULUS. THE TOXIN WAS ADMINISTERED ORALLY IN 50 +/- 10 PPB CONCENTRATION @ 0.05 UGM/ANIMAL/DAY FOR DURATIONS CORRESPONDING TO THE SPAN OF ONE (6 WEEKS) AND TWO (12 WEEKS) SPERMATOGENIC CYCLES. THE RESULTS REVEALED THAT THE FREQUENCY OF ABNORMAL METAPHASE-I PLATES WAS 3% IN THE CONTROL SET, AND AS HIGH AS 47% AFTER 6 WEEKS AND 38% AFTER 12 WEEKS OF TREATMENT. THE ABNORMAL CHROMOSOMES HAD BOTH STRUCTURAL (BREAKS, GAPS, FRAGMENTS, TRANSLOCATIONS, TERMINAL ASSOCIATIONS) AND GROSS (NUMERICAL CHANGES, CLUMPING, STICKINESS) TYPE CHANGES. THE INCIDENCE OF UNIVALENTS OF AUTOSOMES AND SEX-CHROMOSOMES ALSO INCREASED. WHEN THE GIEMSA-STAINED SMEARS OF SPERMS COLLECTED FROM CAUDA EPIDIDYMIS WERE SCREENED, THE FREQUENCY OF SPERM WITH ABNORMAL HEAD INCREASED SIGNIFICANTLY - 2.3 +/- 0.4% IN CONTROL AND 34.5 +/- 1.4% IN 6-WEEK TREATED ANIMALS. THESE STRUCTURAL ABNORMALITIES WERE COINCIDENTAL WITH A REDUCTION IN SPERM COUNT (COLLECTED FROM CAPUT EPIDIDYMIS) BY ABOUT 3.5 TIMES. THE RESULTS THUS SUGGEST THAT THE LONG-TERM CHRONIC EXPOSURE OF MICE TO DIETARY CONCENTRATION OF AFLATOXIN IS (I) CLASTOGENIC FOR MEIOTIC CHROMOSOMES ALSO, (II) CAPABLE OF INDUCING ABNORMALITIES IN SPERM-HEAD MORPHOLOGY AND DECREASING SPERM COUNT. THESE RESULTS ARE IN CONFORMITY WITH EARLIER FINDINGS WHERE THE SAME DOSE AND CONCENTRATION OF THE TOXIN COULD CAUSE HISTOPATHOLOGIC DEGENERATION IN TESTES AND REDUCTION IN FERTILITY.
{"title":"EFFECT OF DIETARY CONCENTRATION OF CRUDE AFLATOXIN ON MEIOTIC CHROMOSOMES, SPERM MORPHOLOGY AND SPERM COUNT IN MICE, MUS MUSCULUS.","authors":"S P Sinha, V Prasad","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>THE CLASTOGENICITY OF THE DIETARY CONCENTRATION OF CRUDE AFLATOXIN (MAINLY B1 AND UNDETECTABLE AMOUNT OF B2, G1 AND G2), HITHERTO WELL-KNOWN IN MITOTICALLY DIVIDING CELLS, WAS TESTED IN METAPHASE-I CHROMOSOMES OF PRIMARY SPERMATOCYTES OF ALBINO SWISS MICE, MUS MUSCULUS. THE TOXIN WAS ADMINISTERED ORALLY IN 50 +/- 10 PPB CONCENTRATION @ 0.05 UGM/ANIMAL/DAY FOR DURATIONS CORRESPONDING TO THE SPAN OF ONE (6 WEEKS) AND TWO (12 WEEKS) SPERMATOGENIC CYCLES. THE RESULTS REVEALED THAT THE FREQUENCY OF ABNORMAL METAPHASE-I PLATES WAS 3% IN THE CONTROL SET, AND AS HIGH AS 47% AFTER 6 WEEKS AND 38% AFTER 12 WEEKS OF TREATMENT. THE ABNORMAL CHROMOSOMES HAD BOTH STRUCTURAL (BREAKS, GAPS, FRAGMENTS, TRANSLOCATIONS, TERMINAL ASSOCIATIONS) AND GROSS (NUMERICAL CHANGES, CLUMPING, STICKINESS) TYPE CHANGES. THE INCIDENCE OF UNIVALENTS OF AUTOSOMES AND SEX-CHROMOSOMES ALSO INCREASED. WHEN THE GIEMSA-STAINED SMEARS OF SPERMS COLLECTED FROM CAUDA EPIDIDYMIS WERE SCREENED, THE FREQUENCY OF SPERM WITH ABNORMAL HEAD INCREASED SIGNIFICANTLY - 2.3 +/- 0.4% IN CONTROL AND 34.5 +/- 1.4% IN 6-WEEK TREATED ANIMALS. THESE STRUCTURAL ABNORMALITIES WERE COINCIDENTAL WITH A REDUCTION IN SPERM COUNT (COLLECTED FROM CAPUT EPIDIDYMIS) BY ABOUT 3.5 TIMES. THE RESULTS THUS SUGGEST THAT THE LONG-TERM CHRONIC EXPOSURE OF MICE TO DIETARY CONCENTRATION OF AFLATOXIN IS (I) CLASTOGENIC FOR MEIOTIC CHROMOSOMES ALSO, (II) CAPABLE OF INDUCING ABNORMALITIES IN SPERM-HEAD MORPHOLOGY AND DECREASING SPERM COUNT. THESE RESULTS ARE IN CONFORMITY WITH EARLIER FINDINGS WHERE THE SAME DOSE AND CONCENTRATION OF THE TOXIN COULD CAUSE HISTOPATHOLOGIC DEGENERATION IN TESTES AND REDUCTION IN FERTILITY.</p>","PeriodicalId":90692,"journal":{"name":"Proceedings of the Indian National Science Academy. Part B, Biological sciences","volume":"B56 3","pages":"269-76"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"36525168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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