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Papers by Valentine Lance
Integrative and Comparative Biology, 2015
![Research paper thumbnail of Studies on the reproductive cycle of the female cobra, Naja naja (L.) [electronic resource]](https://attachments.academia-assets.com/42129152/thumbnails/1.jpg)
](... In Vitro Ovarian Steroid Synthesis VALENTINE LANCE* AND BRIAN LOFTS Department of'Zo... more ... In Vitro Ovarian Steroid Synthesis VALENTINE LANCE* AND BRIAN LOFTS Department of'Zoology, University of Hong Kong, Hong Kong Accepted February 23, 1977 The synthesis of steroids in vitro by minced ... Callard, IP, McChesney, I., Scanes, C., and Callard, GV (1976). ...
Cellular and Molecular Life Sciences CMLS
ABSTRACT
Progress in clinical and biological research
International journal of peptide and protein research
Two molecular forms of prolactin (PRL), glycosylated and non-glycosylated, were isolated from pit... more Two molecular forms of prolactin (PRL), glycosylated and non-glycosylated, were isolated from pituitary glands of two reptiles, alligator and crocodile. The reptilian PRLs were extracted under alkaline conditions from the precipitate obtained after pituitaries were first extracted with 0.25 M sucrose, 1 mM NH4HCO3, pH 6.3. Purification was performed by ion exchange chromatography on DE-52, gel filtration on Sephadex G-75 superfine, and reversed phase high performance liquid chromatography. Two forms of both alligator and crocodile PRL, designated PRLI and PRLII, with molecular weights of 26,000 and 24,000 were isolated. Alligator and crocodile PRLI and PRLII were stained specifically in immunoblots with anti-sea turtle PRL and anti-ostrich PRL. Sequence analysis revealed that both forms of alligator and crocodile PRLs consisted of 199 amino acid residues with a glycosylation consensus sequence (Asn-Ala-Ser) at position 60 in alligator and crocodile PRLs with a molecular weight of 26,000 (PRLI). In contrast, Thr was substituted for Asn at position 60 in the PRLs with a molecular weight of 24,000 (PRLII). The sequences of alligator PRLs differed from crocodile PRLs only in position 134: Val for alligator PRLs and Ile for crocodile PRLs. There is a high degree of structural conservation between the reptilian PRLs isolated in this study and avian PRL; each showed 92% sequence identity with chicken PRL and 89% with turkey PRL.
The American journal of physiology
Incubation of plasma form the alligator (Alligator mississipiensis) with glass beads in the prese... more Incubation of plasma form the alligator (Alligator mississipiensis) with glass beads in the presence of a kininase inhibitor resulted in the activation of the kallikrein-kinin system and generation of bradykinin-like immunoreactivity. The kinin peptides were purified to homogeneity and were shown to comprise [Thr6]-bradykinin and des-Arg9[Thr6]bradykinin in the molar ratio of approximately 10:1. Bolus injections of synthetic [Thr6]bradykinin into the jugular vein of the anesthetized alligator resulted in a dose-dependent decrease in mean arterial blood pressure. The minimum dose of kinin producing a significant fall in pressure was 0.07 micrograms/kg body wt and the maximum response (25 +/- 6% fall; mean +/- SD, n = 8) was produced by a dose of 0.56 micrograms/kg body wt. The dose producing a half-maximum response was 0.19 +/- 0.08 micrograms/kg. The data indicate that alligator plasma contains all the components of the kallikrein-kinin system found in mammals and suggest that the system may be of physiological importance in the regulation of cardiovascular function in these reptiles.
The American journal of physiology
Description of the recessive, homozygote obese Zucker rat (fafa) includes disorders of growth and... more Description of the recessive, homozygote obese Zucker rat (fafa) includes disorders of growth and reproduction. The aim of this study was to compare responsiveness of adenohypophyseal cells, obtained from male fafa rats and from their lean siblings, to growth hormone-releasing factor (GRF) and to luteinizing hormone-releasing hormone (LHRH). Pituitary cells were cultured for 4 days and were then challenged with either GRF-29 (the NH2-terminal 29 amino acid GRF peptide that expresses full biological activity of its parent 44 amino acid molecule) or [D-Trp6]LHRH (LHRH-A, an LHRH agonist). Medium was assayed for growth hormone (GH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) by radioimmunoassay. Dose-response curves were compared using the computer program ALLFIT. The median effective GRF-29 concentration (EC50) computed for hypophyseal cells cultured from lean animals (0.30 +/- 0.01 fM; means +/- SE of 4 experiments) was less (P less than 0.01) than that calculated for cells obtained from fafa rats (15.8 +/- 6.7 fM). In contrast, cells derived from lean littermates required a larger (EC50) concentration of LHRH-A than did gonadotrophs cultured from obese rats [58.2 +/- 1.2 vs. 10.7 +/- 1.2 pM (P less than 0.01) and 59.4 +/- 10.4 vs. 15.7 +/- 7.6 pM (P less than 0.05)] to secrete LH and FSH, respectively. Our data describe an attenuated pituitary response to GRF-29 and an enhanced response to LHRH-A in the fafa.
Journal of Experimental Zoology, 1994
ABSTRACT No abstract is available for this article.
Journal of Experimental Zoology, 1994
Journal of Experimental Zoology, 2001
South American Journal of Herpetology, 2015
Comparative biochemistry and physiology. A, Comparative physiology, 1976
American journal of physiology. Regulatory, integrative and comparative physiology, 2002
The structures and biological activities of the isoforms of endothelin (ET) in a reptile are unkn... more The structures and biological activities of the isoforms of endothelin (ET) in a reptile are unknown. ET-3, whose primary structure is identical to human ET-3 except for the substitution Phe4 --> Tyr, and a peptide identical to human ET-1 were isolated from an extract of the lung of the alligator, Alligator mississipiensis. Bolus intravenous injections of alligator ET-3 (10, 30, and 100 pmol/kg) into anesthetized alligators produced dose-dependent decreases in systemic blood pressure (P(sys)) and systemic vascular resistance (R(sys)) without change in heart rate (HR), systemic blood flow (Q(sys)), pulmonary pressure (P(pul)), pulmonary vascular resistance (R(pul)), or pulmonary blood flow (Q(pul)). At a dose of 300 pmol/kg, the initial vasodilatation was followed by an increase in R(sys) and decreases in Q(sys) and P(pul). The response to intravenous human/alligator ET-1 (10, 30, 100, and 300 pmol/kg) was biphasic at all doses with initial decreases in P(sys) and R(sys) being fol...
Comparative Biochemistry and Physiology Part A: Physiology, 1991
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1983
ABSTRACT
Southeastern Naturalist, 2011
... Valentine A. Lance 1, * , Ruth M. Elsey 2 , Phillip L. Trosclair III 2 and Leisa A. Nunez 2. ... more ... Valentine A. Lance 1, * , Ruth M. Elsey 2 , Phillip L. Trosclair III 2 and Leisa A. Nunez 2. ... Taylor (1984) fitted radio-collars on nine adult female alligators in a lake habitat in north Louisiana and reported home ranges of 0.6 to 256 ha. ...
Integrative and Comparative Biology, 2015
... In Vitro Ovarian Steroid Synthesis VALENTINE LANCE* AND BRIAN LOFTS Department of'Zo... more ... In Vitro Ovarian Steroid Synthesis VALENTINE LANCE* AND BRIAN LOFTS Department of'Zoology, University of Hong Kong, Hong Kong Accepted February 23, 1977 The synthesis of steroids in vitro by minced ... Callard, IP, McChesney, I., Scanes, C., and Callard, GV (1976). ...
Cellular and Molecular Life Sciences CMLS
ABSTRACT
Progress in clinical and biological research
International journal of peptide and protein research
Two molecular forms of prolactin (PRL), glycosylated and non-glycosylated, were isolated from pit... more Two molecular forms of prolactin (PRL), glycosylated and non-glycosylated, were isolated from pituitary glands of two reptiles, alligator and crocodile. The reptilian PRLs were extracted under alkaline conditions from the precipitate obtained after pituitaries were first extracted with 0.25 M sucrose, 1 mM NH4HCO3, pH 6.3. Purification was performed by ion exchange chromatography on DE-52, gel filtration on Sephadex G-75 superfine, and reversed phase high performance liquid chromatography. Two forms of both alligator and crocodile PRL, designated PRLI and PRLII, with molecular weights of 26,000 and 24,000 were isolated. Alligator and crocodile PRLI and PRLII were stained specifically in immunoblots with anti-sea turtle PRL and anti-ostrich PRL. Sequence analysis revealed that both forms of alligator and crocodile PRLs consisted of 199 amino acid residues with a glycosylation consensus sequence (Asn-Ala-Ser) at position 60 in alligator and crocodile PRLs with a molecular weight of 26,000 (PRLI). In contrast, Thr was substituted for Asn at position 60 in the PRLs with a molecular weight of 24,000 (PRLII). The sequences of alligator PRLs differed from crocodile PRLs only in position 134: Val for alligator PRLs and Ile for crocodile PRLs. There is a high degree of structural conservation between the reptilian PRLs isolated in this study and avian PRL; each showed 92% sequence identity with chicken PRL and 89% with turkey PRL.
The American journal of physiology
Incubation of plasma form the alligator (Alligator mississipiensis) with glass beads in the prese... more Incubation of plasma form the alligator (Alligator mississipiensis) with glass beads in the presence of a kininase inhibitor resulted in the activation of the kallikrein-kinin system and generation of bradykinin-like immunoreactivity. The kinin peptides were purified to homogeneity and were shown to comprise [Thr6]-bradykinin and des-Arg9[Thr6]bradykinin in the molar ratio of approximately 10:1. Bolus injections of synthetic [Thr6]bradykinin into the jugular vein of the anesthetized alligator resulted in a dose-dependent decrease in mean arterial blood pressure. The minimum dose of kinin producing a significant fall in pressure was 0.07 micrograms/kg body wt and the maximum response (25 +/- 6% fall; mean +/- SD, n = 8) was produced by a dose of 0.56 micrograms/kg body wt. The dose producing a half-maximum response was 0.19 +/- 0.08 micrograms/kg. The data indicate that alligator plasma contains all the components of the kallikrein-kinin system found in mammals and suggest that the system may be of physiological importance in the regulation of cardiovascular function in these reptiles.
The American journal of physiology
Description of the recessive, homozygote obese Zucker rat (fafa) includes disorders of growth and... more Description of the recessive, homozygote obese Zucker rat (fafa) includes disorders of growth and reproduction. The aim of this study was to compare responsiveness of adenohypophyseal cells, obtained from male fafa rats and from their lean siblings, to growth hormone-releasing factor (GRF) and to luteinizing hormone-releasing hormone (LHRH). Pituitary cells were cultured for 4 days and were then challenged with either GRF-29 (the NH2-terminal 29 amino acid GRF peptide that expresses full biological activity of its parent 44 amino acid molecule) or [D-Trp6]LHRH (LHRH-A, an LHRH agonist). Medium was assayed for growth hormone (GH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) by radioimmunoassay. Dose-response curves were compared using the computer program ALLFIT. The median effective GRF-29 concentration (EC50) computed for hypophyseal cells cultured from lean animals (0.30 +/- 0.01 fM; means +/- SE of 4 experiments) was less (P less than 0.01) than that calculated for cells obtained from fafa rats (15.8 +/- 6.7 fM). In contrast, cells derived from lean littermates required a larger (EC50) concentration of LHRH-A than did gonadotrophs cultured from obese rats [58.2 +/- 1.2 vs. 10.7 +/- 1.2 pM (P less than 0.01) and 59.4 +/- 10.4 vs. 15.7 +/- 7.6 pM (P less than 0.05)] to secrete LH and FSH, respectively. Our data describe an attenuated pituitary response to GRF-29 and an enhanced response to LHRH-A in the fafa.
Journal of Experimental Zoology, 1994
ABSTRACT No abstract is available for this article.
Journal of Experimental Zoology, 1994
Journal of Experimental Zoology, 2001
South American Journal of Herpetology, 2015
Comparative biochemistry and physiology. A, Comparative physiology, 1976
American journal of physiology. Regulatory, integrative and comparative physiology, 2002
The structures and biological activities of the isoforms of endothelin (ET) in a reptile are unkn... more The structures and biological activities of the isoforms of endothelin (ET) in a reptile are unknown. ET-3, whose primary structure is identical to human ET-3 except for the substitution Phe4 --> Tyr, and a peptide identical to human ET-1 were isolated from an extract of the lung of the alligator, Alligator mississipiensis. Bolus intravenous injections of alligator ET-3 (10, 30, and 100 pmol/kg) into anesthetized alligators produced dose-dependent decreases in systemic blood pressure (P(sys)) and systemic vascular resistance (R(sys)) without change in heart rate (HR), systemic blood flow (Q(sys)), pulmonary pressure (P(pul)), pulmonary vascular resistance (R(pul)), or pulmonary blood flow (Q(pul)). At a dose of 300 pmol/kg, the initial vasodilatation was followed by an increase in R(sys) and decreases in Q(sys) and P(pul). The response to intravenous human/alligator ET-1 (10, 30, 100, and 300 pmol/kg) was biphasic at all doses with initial decreases in P(sys) and R(sys) being fol...
Comparative Biochemistry and Physiology Part A: Physiology, 1991
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1983
ABSTRACT
Southeastern Naturalist, 2011
... Valentine A. Lance 1, * , Ruth M. Elsey 2 , Phillip L. Trosclair III 2 and Leisa A. Nunez 2. ... more ... Valentine A. Lance 1, * , Ruth M. Elsey 2 , Phillip L. Trosclair III 2 and Leisa A. Nunez 2. ... Taylor (1984) fitted radio-collars on nine adult female alligators in a lake habitat in north Louisiana and reported home ranges of 0.6 to 256 ha. ...