Richard Beckwitt | Framingham State University (original) (raw)

Papers by Richard Beckwitt

Research paper thumbnail of \u3cem\u3eNephila Clavipes\u3c/em\u3e Dragline Silk: Approaches to a Recombinantly Produced Silk Protein

Spider silks exhibit an unusual combination of strength and toughness that distinguishes them fro... more Spider silks exhibit an unusual combination of strength and toughness that distinguishes them from other natural and synthetic fibers. Silk proteins perform a key natural function as structural fibers, to absorb impact energy from flying insects without breaking. They dissipate energy over a broad area and balance stiffness, strength and extensibility. In addition to their unusual mechanical properties and visual lustre, silks also exhibit interesting interference patterns within the electromagnetic spectrum, unusual viscometric patterns related to processing, and piezoelectric properties. These properties suggest they would be good candidates for high performance fiber and composite applications. However, the spider is not capable of producing sufficient quantities of proteins to enable thorough evaluation of their potential. Consequently, we are pursuing recombinant DNA techniques to clone and express adequate quantities of recombinant spider silk for these studies

Research paper thumbnail of Genetic structure of 'Pileolaria pseudomilitaris' (Polychaeta: Spirorbidae) in Southern California

Research paper thumbnail of Genetic Structure of Pileolaria Pseudomilitaris (Polychaeta: Spirorbidae)

Genetics, 1980

The genetic structure of Pileolaria pseudomilitaris was studied by means of gene-diversity analys... more The genetic structure of Pileolaria pseudomilitaris was studied by means of gene-diversity analysis of allozyme frequencies. At an esterase locus, most of the gene diversity was due to subdivision of the population into colonies and subpopulations separated by less than 100 meters. Gene frequencies at a phosphoglucose isomerase locus were similar over many kilometers, but differed between two habitat types. Differences between colonies are attributed to drift and founder effect; similarities over greater distances are attributed to similar selection pressures. A mathematical appendix details the method of gene diversity analysis for a multi-leveled, hierarchically subdivided population.

Research paper thumbnail of Sequence conservation in the C-terminal region of spider silk proteins (Spidroin) from Nephila clavipes (Tetragnathidae) and Araneus bicentenarius (Araneidae)

Journal of Biological Chemistry, 1994

The polymerase chain reaction (PCR) has been used to amplify the portion of the Spidroin 1 gene t... more The polymerase chain reaction (PCR) has been used to amplify the portion of the Spidroin 1 gene that codes for the C-terminal part of the silk protein of the spider Nephila clavipes. Along with some substitution mutations of minor consequence, the PCR-derived sequence reveals an additional base missing from the previously published Nephila Spidroin 1 sequence. Comparison of the PCR-derived sequence with the equivalent region of Spidroin 2 indicates that the insertion of this single base results in greatly increased similarity in the resulting amino acid sequences of Spidroin 1 and Spidroin 2 (75% over 97 amino acids). The same PCR primers also amplified a fragment of the same length from Araneus bicentenarius. This sequence is also very similar to Spidroin 1 of Nephila (71% over 238 bases excluding the PCR primers, which translates into 76% over 79 amino acids).

Research paper thumbnail of Mitochondrial DNA sequence variation inHippopotamus amphibiusfrom Kruger National Park, Republic of South Africa

African Zoology, 2016

Populations of Hippopotamus amphibius have declined throughout Africa in recent years, and are ex... more Populations of Hippopotamus amphibius have declined throughout Africa in recent years, and are expected to decline further. An understanding of the population genetics of individual populations of hippos is necessary for effective management. To that end, we sequenced a portion of the mitochondrial DNA (mtDNA) control region or D-loop from 37 H. amphibius, from six herds in the central region of Kruger National Park (KNP), Republic of South Africa. We amplified a 453 bp segment by PCR, and identified 21 polymorphic sites and seven haplotypes. All of these haplotypes are private alleles, not found in other populations of hippos from southern Africa. Overall nucleotide diversity (π) was 0.01739, and haplotype diversity (hd) was 0.8273, within the range observed in other parts of Africa. Mismatch analysis conformed more closely to a model of constant population size than either rapid demographic or spatial expansion. An analysis of molecular variance demonstrated no significant differentiation among herds, and Mantel tests showed no significant relationship between geographic and genetic distance among herds separated by up to 47 km (measured as Euclidean [x,y] distance) or 77 km (measured along rivers). Over this range, the population appears to be a single panmictic unit. A test of the hypothesis that calves are more likely to share a mtDNA haplotype with an adult female in the same herd than an adult female from a different herd was not significant.

Research paper thumbnail of A PCR-based method for sex identification in Hippopotamus amphibius

African Zoology, 2002

Page 1. A PCR-based method for sex identification in Hippopotamus amphibius Richard Beckwitt&#x27... more Page 1. A PCR-based method for sex identification in Hippopotamus amphibius Richard Beckwitt'', Jennifer Shea1, Deirdre Osborne1, Stephen Krueger2 & William Barklow1 Department of Biology, Framìngham Siate Collège ... James Uthoff helped to collect the samples in Africa. ...

Research paper thumbnail of Biosynthesis and Processing of Silk Proteins

MRS Bulletin, 1992

Silks produced by silkworms (e.g.,Bombyx mori) and orb-web weaving spiders (e.g.,Nephila clavipes... more Silks produced by silkworms (e.g.,Bombyx mori) and orb-web weaving spiders (e.g.,Nephila clavipes) are essentially pure protein, that is, complexes of amino acid polymers. They are the most common fibers spun by biological systems. There has been a long-standing interest in the use of these and similar fibers in textiles, cables, fiber reinforcement in composites, in addition, for example, to cross hairs in optical instruments, and fishing nets. Both nylon, a homo-polymer of the amino acid glycine, and Kevlar, a polymer of a nonnatural aromatic amino acid, can be considered modified, synthetic versions of silk and are used for some of the applications mentioned above. The potential for genetic manipulation, through recombinant DNA technology, of the natural biosynthetic process for these natural proteins (see the article by Cappello in this issue) has renewed interest in the production of new silklike proteins.The natural silks are characterized by aβ-sheet secondary structure which...

Research paper thumbnail of Population Genetics of an Introduced Species: Bairdiella icistius in the Salton Sea

Bulletin of the Southern California Academy of Sciences, 1987

The bairdiella, Bairdiella icistius (Jordan and Gilbert), in the Salton Sea are the progeny of a ... more The bairdiella, Bairdiella icistius (Jordan and Gilbert), in the Salton Sea are the progeny of a successful introduction made in the 1950\u27s. They form a central link in a productive and heavily utilized sportfishery. Genetic variabihty at 56 enzyme and protein loci was studied by means of starch and polyacrylamide gel electrophoresis. Eight loci were polymorphic, and all polymorphic loci were close to Hardy- Weinberg equilibrium. Average heterozygosity per locus was 0.043, which is within the typical range for marine fish species. There appeared to be fewer rare alleles than expected in a population at equilibrium. The Salton Sea habitat is harsh and changing. The amount of genetic variability present in the bairdiella is an indication of the ability of this population to adapt to environ- mental change

Research paper thumbnail of Electrophoretic Evidence for Self-fertilization in Two Species of Spirorbid Polychaetes

Bulletin of the Southern California Academy of Sciences, 1982

Electrophoretic evidence for self-fertilization in two species of spirorbid polychaetes by Richar... more Electrophoretic evidence for self-fertilization in two species of spirorbid polychaetes by Richard Beckwitt, Bull. Southern California Acad. Sci., 81(2):61-68, 1982. The inheritance of electrophoretically detectable enzymatic variation was studied by means of laboratory culture of Pileolaria pseudomilitaris and Janua brasiliensis. These variants are inherited as simple Mendelian codominants in single-pair matings. A small percentage of progeny from single-pair matings of each species are produced by self-fertilization in these hermaphroditic worms. Isolated individuals of P. pseudomilitaris produced reduced numbers of progeny with genotypes that confirmed self-fertilization by the parent. Isolated individuals of J. brasiliensis did not reproduce in culture. The high degree of polymorphism at several loci suggests that self-fertilization is not a common occurrence in natural populations

Research paper thumbnail of Nephila Clavipes Dragline Silk: Approaches to a Recombinantly Produced Silk Protein

MRS Proceedings, 1993

Spider silks exhibit an unusual combination of strength and toughness that distinguishes them fro... more Spider silks exhibit an unusual combination of strength and toughness that distinguishes them from other natural and synthetic fibers. Silk proteins perform a key natural function as structural fibers, to absorb impact energy from flying insects without breaking. They dissipate energy over a broad area and balance stiffness, strength and extensibility (1,2). In addition to their unusual mechanical properties and visual lustre, silks also exhibit interesting interference patterns within the electromagnetic spectrum (3), unusual viscometric patterns related to processing (4), and piezoelectric properties (3,5,6). These properties suggest they would be good candidates for high performance fiber and composite applications. However, the spider is not capable of producing sufficient quantities of proteins to enable thorough evaluation of their potential. Consequently, we are pursuing recombinant DNA techniques to clone and express adequate quantities of recombinant spider silk for these s...

Research paper thumbnail of The inheritance of morphological variation in Pileolaria pseudomilitaris (Polychaeta: Spirorbidae)

Zoological Journal of the Linnean Society, 1981

The genetic control of morphological variation (expressed as heritability) was examined by means ... more The genetic control of morphological variation (expressed as heritability) was examined by means of laboratory culture in Pileolaria pseudomilitaris. Fourteen of 22 traits examined were shown to have an appreciable genetic component, after an analysis of variance among groups of full siblings. The range of variability for several traits is as large within a single sibling group as the difference between described species in the family. Comparisons among samples of P. pseudomilitaris from two habitats revealed no consistent morphological dillerences. A similar comparison between P. pseudomilitaris and its nearest congener, I', potswaldi, indicated significant differences for 15 of 22 traits, although ranges overlapped for all bin two of these.

Research paper thumbnail of Population genetics of the sand crab, Emerita analoga Stimpson, in southern California

Journal of Experimental Marine Biology and Ecology, 1985

Genetic variation at 25 enzymatic loci was studied by means of starch and acrylamide gel electrop... more Genetic variation at 25 enzymatic loci was studied by means of starch and acrylamide gel electrophoresis in six samples of the sand crab, Emerita analoga Stimpson, from southern California. Average heterozygosity was 0.07 + 0.03 (SE) and five loci were polymorphic. Allele frequencies at a malate dehydrogenase locus were significantly different among samples. Genotype frequencies at an esterase locus and a phosphoglucomutase locus showed significant deviations from Hardy-Weinberg equilibrium in some samples. The activity of phosphoglucomutase was reduced in samples taken from the vicinity of the San Onofre Nuclear Generating Station (SONGS) and from Cabrillo Beach near Los Angeles Harbor. It has not been determined whether this is due to a decrease in the amount of the enzyme present, an inhibition of its activity or some other cause.

Research paper thumbnail of Evolution of repetitive proteins: spider silks from Nephila clavipes (Tetragnathidae) and Araneus bicentenarius (Araneidae)1GenBank assigned accession number(s):Araneus: U20328; Nephila: cDNA = U20329, PCR = U375201

Insect Biochemistry and Molecular Biology, 1998

Spider silks are highly repetitive proteins, characterized by regions of polyalanine and glycine-... more Spider silks are highly repetitive proteins, characterized by regions of polyalanine and glycine-rich repeating units. We have obtained two variants of the Spidroin 1 (NCF-1) silk gene sequence from Nephila clavipes. One sequence (1726 bp) was from a cloned cDNA, and the other (1951 bp) was from PCR of genomic DNA. When these sequences are compared with each other and the previously published Spidroin 1 sequence, there are differences due to sequence rearrangements, as well as single base substitutions. These variations are similar to those that have been reported from other highly repetitive genes, and probably represent the results of unequal cross-overs. We have also obtained 708 bp of sequence from PCR of genomic DNA from Araneus bicentenarius. This sequence shows considerable similarity to a dragline sequence (ADF-3) from A. diadematus, as well as Spidroin 2 (NCF-2) from N. clavipes. Minor but consistent differences in the repeating unit sequence between A. bicentenarius and A. diadematus suggest that concerted evolution or gene conversion processes are acting to maintain similarity among repeat units within a single gene.

Research paper thumbnail of Genetic Structure of Genyonemus lineatus, Seriphus politus (Sciaenidae) and Paralabrax clathratus (Serranidae) in Southern California

Research paper thumbnail of Mitochondrial DNA Sequence Variation in Domesticated Goldfish, Carassius auratus

Research paper thumbnail of Variation in Mitochondrial DNA Genome Size among Fishes of the Family Scorpaenidae

Copeia, 1985

... Gambusia xanthosoma, a new species of poeciliid fish from Grand Cayman Island, BWI Copeia 198... more ... Gambusia xanthosoma, a new species of poeciliid fish from Grand Cayman Island, BWI Copeia 1983:457-464. ... Prior to electrophoresis, to fill-in ends and gaps in DNA molecules, the DNA of some sam-ples was incubated for 4 h at 8 C with the Kle-now (large) fragment of DNA ...

Research paper thumbnail of Recombinant expression of indolicidin concatamers in Escherichia coli

Applied Microbiology and Biotechnology, 2005

Antimicrobial peptides are part of the innate immune system of vertebrates and invertebrates. The... more Antimicrobial peptides are part of the innate immune system of vertebrates and invertebrates. They are active against gram-negative and gram-positive bacteria, fungi, and protozoa. Currently, most antimicrobial peptides are extracted from host organisms or produced by solidphase peptide synthesis. Recombinant protein expression in Escherichia coli is a tool for greater production yields at a decreased cost and reduces the use of hazardous materials. We have constructed a concatamer of indolicidin and successfully expressed a fusion product with thioredoxin in E. coli BL21DE3. Codons for methionine residues flanking individual indolicidin genes were incorporated for cyanogen bromide cleavage of the fusion protein and liberation of active monomeric indolicidin. Peptide yields of 150 μg/l monomeric indolicidin were achieved in this first report of recombinant production of indolicidin with demonstrated antimicrobial activity.

Research paper thumbnail of Phylogeny and historical biogeography of the spider genus Lutica (Araneae, Zodariidae)

Journal of Arachnology, 1995

Spiders of the genus Lutica from 19 populations in southern California and Baja California, inclu... more Spiders of the genus Lutica from 19 populations in southern California and Baja California, including all the California Channel Islands except Anacapa, were compared electrophoretically on the basis of variability at 15 gene loci. Fixed allelic differences clearly define two species: new species A [Santa Barbara and Ventura Counties, northern Channel Islands (San Miguel, Santa Rosa, Santa Cruz), southern Channel Islands (San Nicolas, Santa Barbara, Santa Catalina)] and new species C [Guerrero Negro, central Baja ...

Research paper thumbnail of \u3cem\u3eNephila Clavipes\u3c/em\u3e Dragline Silk: Approaches to a Recombinantly Produced Silk Protein

Spider silks exhibit an unusual combination of strength and toughness that distinguishes them fro... more Spider silks exhibit an unusual combination of strength and toughness that distinguishes them from other natural and synthetic fibers. Silk proteins perform a key natural function as structural fibers, to absorb impact energy from flying insects without breaking. They dissipate energy over a broad area and balance stiffness, strength and extensibility. In addition to their unusual mechanical properties and visual lustre, silks also exhibit interesting interference patterns within the electromagnetic spectrum, unusual viscometric patterns related to processing, and piezoelectric properties. These properties suggest they would be good candidates for high performance fiber and composite applications. However, the spider is not capable of producing sufficient quantities of proteins to enable thorough evaluation of their potential. Consequently, we are pursuing recombinant DNA techniques to clone and express adequate quantities of recombinant spider silk for these studies

Research paper thumbnail of Genetic structure of 'Pileolaria pseudomilitaris' (Polychaeta: Spirorbidae) in Southern California

Research paper thumbnail of Genetic Structure of Pileolaria Pseudomilitaris (Polychaeta: Spirorbidae)

Genetics, 1980

The genetic structure of Pileolaria pseudomilitaris was studied by means of gene-diversity analys... more The genetic structure of Pileolaria pseudomilitaris was studied by means of gene-diversity analysis of allozyme frequencies. At an esterase locus, most of the gene diversity was due to subdivision of the population into colonies and subpopulations separated by less than 100 meters. Gene frequencies at a phosphoglucose isomerase locus were similar over many kilometers, but differed between two habitat types. Differences between colonies are attributed to drift and founder effect; similarities over greater distances are attributed to similar selection pressures. A mathematical appendix details the method of gene diversity analysis for a multi-leveled, hierarchically subdivided population.

Research paper thumbnail of Sequence conservation in the C-terminal region of spider silk proteins (Spidroin) from Nephila clavipes (Tetragnathidae) and Araneus bicentenarius (Araneidae)

Journal of Biological Chemistry, 1994

The polymerase chain reaction (PCR) has been used to amplify the portion of the Spidroin 1 gene t... more The polymerase chain reaction (PCR) has been used to amplify the portion of the Spidroin 1 gene that codes for the C-terminal part of the silk protein of the spider Nephila clavipes. Along with some substitution mutations of minor consequence, the PCR-derived sequence reveals an additional base missing from the previously published Nephila Spidroin 1 sequence. Comparison of the PCR-derived sequence with the equivalent region of Spidroin 2 indicates that the insertion of this single base results in greatly increased similarity in the resulting amino acid sequences of Spidroin 1 and Spidroin 2 (75% over 97 amino acids). The same PCR primers also amplified a fragment of the same length from Araneus bicentenarius. This sequence is also very similar to Spidroin 1 of Nephila (71% over 238 bases excluding the PCR primers, which translates into 76% over 79 amino acids).

Research paper thumbnail of Mitochondrial DNA sequence variation inHippopotamus amphibiusfrom Kruger National Park, Republic of South Africa

African Zoology, 2016

Populations of Hippopotamus amphibius have declined throughout Africa in recent years, and are ex... more Populations of Hippopotamus amphibius have declined throughout Africa in recent years, and are expected to decline further. An understanding of the population genetics of individual populations of hippos is necessary for effective management. To that end, we sequenced a portion of the mitochondrial DNA (mtDNA) control region or D-loop from 37 H. amphibius, from six herds in the central region of Kruger National Park (KNP), Republic of South Africa. We amplified a 453 bp segment by PCR, and identified 21 polymorphic sites and seven haplotypes. All of these haplotypes are private alleles, not found in other populations of hippos from southern Africa. Overall nucleotide diversity (π) was 0.01739, and haplotype diversity (hd) was 0.8273, within the range observed in other parts of Africa. Mismatch analysis conformed more closely to a model of constant population size than either rapid demographic or spatial expansion. An analysis of molecular variance demonstrated no significant differentiation among herds, and Mantel tests showed no significant relationship between geographic and genetic distance among herds separated by up to 47 km (measured as Euclidean [x,y] distance) or 77 km (measured along rivers). Over this range, the population appears to be a single panmictic unit. A test of the hypothesis that calves are more likely to share a mtDNA haplotype with an adult female in the same herd than an adult female from a different herd was not significant.

Research paper thumbnail of A PCR-based method for sex identification in Hippopotamus amphibius

African Zoology, 2002

Page 1. A PCR-based method for sex identification in Hippopotamus amphibius Richard Beckwitt&#x27... more Page 1. A PCR-based method for sex identification in Hippopotamus amphibius Richard Beckwitt'', Jennifer Shea1, Deirdre Osborne1, Stephen Krueger2 & William Barklow1 Department of Biology, Framìngham Siate Collège ... James Uthoff helped to collect the samples in Africa. ...

Research paper thumbnail of Biosynthesis and Processing of Silk Proteins

MRS Bulletin, 1992

Silks produced by silkworms (e.g.,Bombyx mori) and orb-web weaving spiders (e.g.,Nephila clavipes... more Silks produced by silkworms (e.g.,Bombyx mori) and orb-web weaving spiders (e.g.,Nephila clavipes) are essentially pure protein, that is, complexes of amino acid polymers. They are the most common fibers spun by biological systems. There has been a long-standing interest in the use of these and similar fibers in textiles, cables, fiber reinforcement in composites, in addition, for example, to cross hairs in optical instruments, and fishing nets. Both nylon, a homo-polymer of the amino acid glycine, and Kevlar, a polymer of a nonnatural aromatic amino acid, can be considered modified, synthetic versions of silk and are used for some of the applications mentioned above. The potential for genetic manipulation, through recombinant DNA technology, of the natural biosynthetic process for these natural proteins (see the article by Cappello in this issue) has renewed interest in the production of new silklike proteins.The natural silks are characterized by aβ-sheet secondary structure which...

Research paper thumbnail of Population Genetics of an Introduced Species: Bairdiella icistius in the Salton Sea

Bulletin of the Southern California Academy of Sciences, 1987

The bairdiella, Bairdiella icistius (Jordan and Gilbert), in the Salton Sea are the progeny of a ... more The bairdiella, Bairdiella icistius (Jordan and Gilbert), in the Salton Sea are the progeny of a successful introduction made in the 1950\u27s. They form a central link in a productive and heavily utilized sportfishery. Genetic variabihty at 56 enzyme and protein loci was studied by means of starch and polyacrylamide gel electrophoresis. Eight loci were polymorphic, and all polymorphic loci were close to Hardy- Weinberg equilibrium. Average heterozygosity per locus was 0.043, which is within the typical range for marine fish species. There appeared to be fewer rare alleles than expected in a population at equilibrium. The Salton Sea habitat is harsh and changing. The amount of genetic variability present in the bairdiella is an indication of the ability of this population to adapt to environ- mental change

Research paper thumbnail of Electrophoretic Evidence for Self-fertilization in Two Species of Spirorbid Polychaetes

Bulletin of the Southern California Academy of Sciences, 1982

Electrophoretic evidence for self-fertilization in two species of spirorbid polychaetes by Richar... more Electrophoretic evidence for self-fertilization in two species of spirorbid polychaetes by Richard Beckwitt, Bull. Southern California Acad. Sci., 81(2):61-68, 1982. The inheritance of electrophoretically detectable enzymatic variation was studied by means of laboratory culture of Pileolaria pseudomilitaris and Janua brasiliensis. These variants are inherited as simple Mendelian codominants in single-pair matings. A small percentage of progeny from single-pair matings of each species are produced by self-fertilization in these hermaphroditic worms. Isolated individuals of P. pseudomilitaris produced reduced numbers of progeny with genotypes that confirmed self-fertilization by the parent. Isolated individuals of J. brasiliensis did not reproduce in culture. The high degree of polymorphism at several loci suggests that self-fertilization is not a common occurrence in natural populations

Research paper thumbnail of Nephila Clavipes Dragline Silk: Approaches to a Recombinantly Produced Silk Protein

MRS Proceedings, 1993

Spider silks exhibit an unusual combination of strength and toughness that distinguishes them fro... more Spider silks exhibit an unusual combination of strength and toughness that distinguishes them from other natural and synthetic fibers. Silk proteins perform a key natural function as structural fibers, to absorb impact energy from flying insects without breaking. They dissipate energy over a broad area and balance stiffness, strength and extensibility (1,2). In addition to their unusual mechanical properties and visual lustre, silks also exhibit interesting interference patterns within the electromagnetic spectrum (3), unusual viscometric patterns related to processing (4), and piezoelectric properties (3,5,6). These properties suggest they would be good candidates for high performance fiber and composite applications. However, the spider is not capable of producing sufficient quantities of proteins to enable thorough evaluation of their potential. Consequently, we are pursuing recombinant DNA techniques to clone and express adequate quantities of recombinant spider silk for these s...

Research paper thumbnail of The inheritance of morphological variation in Pileolaria pseudomilitaris (Polychaeta: Spirorbidae)

Zoological Journal of the Linnean Society, 1981

The genetic control of morphological variation (expressed as heritability) was examined by means ... more The genetic control of morphological variation (expressed as heritability) was examined by means of laboratory culture in Pileolaria pseudomilitaris. Fourteen of 22 traits examined were shown to have an appreciable genetic component, after an analysis of variance among groups of full siblings. The range of variability for several traits is as large within a single sibling group as the difference between described species in the family. Comparisons among samples of P. pseudomilitaris from two habitats revealed no consistent morphological dillerences. A similar comparison between P. pseudomilitaris and its nearest congener, I', potswaldi, indicated significant differences for 15 of 22 traits, although ranges overlapped for all bin two of these.

Research paper thumbnail of Population genetics of the sand crab, Emerita analoga Stimpson, in southern California

Journal of Experimental Marine Biology and Ecology, 1985

Genetic variation at 25 enzymatic loci was studied by means of starch and acrylamide gel electrop... more Genetic variation at 25 enzymatic loci was studied by means of starch and acrylamide gel electrophoresis in six samples of the sand crab, Emerita analoga Stimpson, from southern California. Average heterozygosity was 0.07 + 0.03 (SE) and five loci were polymorphic. Allele frequencies at a malate dehydrogenase locus were significantly different among samples. Genotype frequencies at an esterase locus and a phosphoglucomutase locus showed significant deviations from Hardy-Weinberg equilibrium in some samples. The activity of phosphoglucomutase was reduced in samples taken from the vicinity of the San Onofre Nuclear Generating Station (SONGS) and from Cabrillo Beach near Los Angeles Harbor. It has not been determined whether this is due to a decrease in the amount of the enzyme present, an inhibition of its activity or some other cause.

Research paper thumbnail of Evolution of repetitive proteins: spider silks from Nephila clavipes (Tetragnathidae) and Araneus bicentenarius (Araneidae)1GenBank assigned accession number(s):Araneus: U20328; Nephila: cDNA = U20329, PCR = U375201

Insect Biochemistry and Molecular Biology, 1998

Spider silks are highly repetitive proteins, characterized by regions of polyalanine and glycine-... more Spider silks are highly repetitive proteins, characterized by regions of polyalanine and glycine-rich repeating units. We have obtained two variants of the Spidroin 1 (NCF-1) silk gene sequence from Nephila clavipes. One sequence (1726 bp) was from a cloned cDNA, and the other (1951 bp) was from PCR of genomic DNA. When these sequences are compared with each other and the previously published Spidroin 1 sequence, there are differences due to sequence rearrangements, as well as single base substitutions. These variations are similar to those that have been reported from other highly repetitive genes, and probably represent the results of unequal cross-overs. We have also obtained 708 bp of sequence from PCR of genomic DNA from Araneus bicentenarius. This sequence shows considerable similarity to a dragline sequence (ADF-3) from A. diadematus, as well as Spidroin 2 (NCF-2) from N. clavipes. Minor but consistent differences in the repeating unit sequence between A. bicentenarius and A. diadematus suggest that concerted evolution or gene conversion processes are acting to maintain similarity among repeat units within a single gene.

Research paper thumbnail of Genetic Structure of Genyonemus lineatus, Seriphus politus (Sciaenidae) and Paralabrax clathratus (Serranidae) in Southern California

Research paper thumbnail of Mitochondrial DNA Sequence Variation in Domesticated Goldfish, Carassius auratus

Research paper thumbnail of Variation in Mitochondrial DNA Genome Size among Fishes of the Family Scorpaenidae

Copeia, 1985

... Gambusia xanthosoma, a new species of poeciliid fish from Grand Cayman Island, BWI Copeia 198... more ... Gambusia xanthosoma, a new species of poeciliid fish from Grand Cayman Island, BWI Copeia 1983:457-464. ... Prior to electrophoresis, to fill-in ends and gaps in DNA molecules, the DNA of some sam-ples was incubated for 4 h at 8 C with the Kle-now (large) fragment of DNA ...

Research paper thumbnail of Recombinant expression of indolicidin concatamers in Escherichia coli

Applied Microbiology and Biotechnology, 2005

Antimicrobial peptides are part of the innate immune system of vertebrates and invertebrates. The... more Antimicrobial peptides are part of the innate immune system of vertebrates and invertebrates. They are active against gram-negative and gram-positive bacteria, fungi, and protozoa. Currently, most antimicrobial peptides are extracted from host organisms or produced by solidphase peptide synthesis. Recombinant protein expression in Escherichia coli is a tool for greater production yields at a decreased cost and reduces the use of hazardous materials. We have constructed a concatamer of indolicidin and successfully expressed a fusion product with thioredoxin in E. coli BL21DE3. Codons for methionine residues flanking individual indolicidin genes were incorporated for cyanogen bromide cleavage of the fusion protein and liberation of active monomeric indolicidin. Peptide yields of 150 μg/l monomeric indolicidin were achieved in this first report of recombinant production of indolicidin with demonstrated antimicrobial activity.

Research paper thumbnail of Phylogeny and historical biogeography of the spider genus Lutica (Araneae, Zodariidae)

Journal of Arachnology, 1995

Spiders of the genus Lutica from 19 populations in southern California and Baja California, inclu... more Spiders of the genus Lutica from 19 populations in southern California and Baja California, including all the California Channel Islands except Anacapa, were compared electrophoretically on the basis of variability at 15 gene loci. Fixed allelic differences clearly define two species: new species A [Santa Barbara and Ventura Counties, northern Channel Islands (San Miguel, Santa Rosa, Santa Cruz), southern Channel Islands (San Nicolas, Santa Barbara, Santa Catalina)] and new species C [Guerrero Negro, central Baja ...