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119 results on '"Borst, David W."'

10. Intraspecific mitochondrial DNA variation and historical biogeography of the eastern lubber grasshopper, romalea microptera

Author

Mutun, Serap, Borst, David W., BAİBÜ, Fen Edebiyat Fakültesi, Biyoloji Bölümü, and Mutun, Serap

Subjects
Gene Flow, Intraspecific Variation, MtDNA, Genetic Variation, Eastern Lubber Rrasshopper
Abstract

WOS:000222642400008 The genetic and geographical variation, gene flow, and the historical biogeography of the eastern lubber grasshopper, Romalea microptera (=guttata) (Houttuyn), were examined by sequencing a 420-bp region of the mitochondrial cytochrome b gene. Individuals (168) were collected from 12 sites in the southern United States that covered most of the range reported for this species. These populations contained 49 mitochondrial DNA haplotypes. A high level of genetic diversity was observed in these populations (3.8%), most of which was due to variation within populations. The highest genetic variation was found in a northern Florida population (collected at St. Marks, FL), and the lowest was found in a southern Florida population (Copeland, FL). Estimates of historical and current population sizes suggest that most of the lubber populations drastically declined in size at some point in the past. In contrast to previous studies on several other species in this region, phylogenetic analyses (PAUP) and haplotype age phylogenies (PHYLIP) showed no major geographic structure. These observations suggest that the distribution of this species in the past may have been homogeneous, rather than the patchy distribution that is currently observed. Alternatively, this result may reflect the absence of long-term barriers for the dispersal of this species. Either of these might have contributed to the lack of a genetic structure divided geographically into east-west groupings that is seen in other species from this region.

Published
2004

11. Physiological stress elevate hemolymph levels of methyl farnesoate in the green crab Carcinus maenas

Author

Lovett, Donald L., Clifford, Patrick D., and Borst, David W.

Subjects
Crabs -- Physiological aspects -- Research, Crustacea -- Physiological aspects -- Research, Methyl groups -- Physiological aspects -- Research, Stress (Physiology) -- Research -- Physiological aspects, Biological sciences, Physiological aspects, Research
Abstract

Methyl farnesoate (MF), a sesquiterpene from crustaceans, is structurally similar to insect juvenile hormone. Thus it may have a role in regulating crustacean metamorphosis, reproduction, and behavior (1, 2). In [...]

Published
1997

12. Relationship of methyl transferase activity and methyl farnesoate levels in the spider crab, Libinia emarginata

Author

Ogan, Jeff, Shaub, Amy, Lovett, Donald L., and Borst, David W.

Subjects
Crabs -- Physiological aspects, Methyl groups -- Physiological aspects, Crustacea -- Physiological aspects, Methyltransferases -- Physiological aspects, Biological sciences, Physiological aspects
Abstract

Methyl farnesoate (MF) is a sesquiterpene produced by the crustacean mandibular organ (MO). Although MF is structurally similar to insect juvenile hormone, the functions of this compound in crustaceans are [...]

Published
1997

35. Characterization of methyl transferase activity in the mandibular organ of the American lobster, Homarus americanus

Author

Claerhout, Todd, Bendena, William, Tobe, Stephen S., and Borst, David W.

Subjects
American lobster -- Physiological aspects, Methyltransferases -- Physiological aspects, Biological sciences, Physiological aspects
Abstract

The crustacean mandibular organ (MO) is the site of synthesis of methyl farnesoate (MF), a sesquiterpene structurally related to insect juvenile hormone (JH). Although the role of MF in crustaceans [...]

Published
1996

41. Effects of eyestalk ablation on carbonic anhydrase activity in the euryhaline blue crab Callinectes sapidus: neuroendocrine control of enzyme expression

Author

Henry, Raymond P. and Borst, David W.

Abstract

Carbonic anhydrase (CA) activity in the gills of the euryhaline blue crab, Callinectes sapidus, was measured in response to acute low‐salinity transfer and treatment with eyestalk ablation (ESA) in an attempt to elucidate potential regulatory mechanisms of salinity‐mediated CA induction. ESA alone resulted in an approximate doubling of CA activity in the posterior, ion‐transporting gills of crabs acclimated to 35 ppt. Transfer of intact crabs to 28 ppt, a salinity at which the blue crab is still an osmotic and ionic conformer, had no effect on CA activity, but treatment with ESA prior to transfer resulted in a 5‐fold increase. Hemolymph osmolality was unaffected by ESA. There was a 7‐fold induction of CA activity in posterior gills of intact crabs transferred from 35 to 15 ppt, and this was potentiated by about 100% by ESA. Hemolymph osmolality was slightly elevated in the ESA‐treated crabs. CA activity in anterior gills did not increase in response to any treatment. Hemolymph concentrations of methyl farnesoate (MF) were measured for all experimental animals. MF concentrations were undetectable in all intact crabs, regardless of salinity. Treatment with ESA resulted in elevated levels of hemolymph MF, but these levels were still relatively low and unrelated to salinity. These results suggest that CA induction is under the control of a regulatory substance located in the eyestalk. This substance appears to be a CA repressor, keeping CA expression at low levels in the gills of crabs acclimated to high salinity. Exposure to low salinity, or treatment with ESA, removes the effects of this putative repressor and allows CA induction to occur. J. Exp. Zool. 305A:23–31, 2006. © 2005 Wiley‐Liss, Inc.

Published
2006
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44. Characterization and quantification of yolk proteins in the lobster, <TOGGLE>Homarus americanus</TOGGLE>

Author

Tsukimura, Brian, Waddy, Susan L., Vogel, Jacalyn M., Linder, Colby J., Bauer, Daniel K., and Borst, David W.

Abstract

Yolk protein (vitellin, Vn) and its precursor (vitellogenin, Vg) were isolated and characterized in the ovary and hemolymph, respectively, of the adult female lobster, Homarus americanus. Vn had a molecular mass of 360 kDa when analyzed by gel filtration. When analyzed by SDS-PAGE, Vn had six bands (110, 105, 94, 90, 81, and 78 kDa). An anti-Vn antiserum was developed using purified Vn, and the antiserum was used to detect Vn and Vg by ELISA and western blot techniques. ELISA analysis of hemolymph proteins separated by gel filtration indicated that Vg was similar in mass to Vn (360 kDa). However, western blots of hemolymph proteins separated by SDS-PAGE indicated that Vg contained a pair of protein subunits, 194 kDa and 179 kDa. Furthermore, the elution profiles of Vn and Vg from anion exchange chromatography indicated that Vg had a more negative charge. Thus, Vg appears to be processed after its uptake by the ovary to form Vn. Vg was undetectable in hemolymph from adult males by either ELISA or by western blot analysis. However, hemolymph levels of Vg in adult females increased 40-fold during the reproductive cycle, rising from 18 μg/mL in ovarian stage II to 789 μg/mL at stage V. This increase correlates well with oocyte growth during the cycle. Hence, this method may be useful for studying the regulation of lobster vitellogenesis. J. Exp. Zool. 292:367–375, 2002. © 2002 Wiley-Liss, Inc.

Published
2002
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