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Cheryl Y. Hayashi - One of the best experts on this subject based on the ideXlab platform.
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dissection of silk glands in the western black widow Latrodectus hesperus
Journal of Arachnology, 2018Co-Authors: Crystal R Chaw, Cheryl Y. HayashiAbstract:The silk glands of the Western black widow Latrodectus hesperus Chamberlin & Ivie, 1935 are morphologically and functionally distinct. Studies of spider silk glands often show only high magnification images of sections or drawings of glands, making differentiation of dissected glands difficult. We dissect all of the gland types from L. hesperus females and show their gross morphology with light microscopy. Our micrographs portray the distinct morphologies and relative sizes of each silk gland type, consistent with prior descriptions of the silk apparatus of Latrodectus spiders. Notably, we verify the presence of two differentiated pairs of aggregate silk glands and spigots, thus resolving a discrepancy in the literature.
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Molecular evolution of α-latrotoxin, the exceptionally potent vertebrate neurotoxin in black widow spider venom
Molecular biology and evolution, 2013Co-Authors: Jessica E. Garb, Cheryl Y. HayashiAbstract:Black widow spiders (members of the genus Latrodectus) are widely feared because of their potent neurotoxic venom. α-Latrotoxin is the vertebrate-specific toxin responsible for the dramatic effects of black widow envenomation. The evolution of this toxin is enigmatic because only two α-latrotoxin sequences are known. In this study, ∼4 kb α-latrotoxin sequences and their homologs were characterized from a diversity of Latrodectus species, and representatives of Steatoda and Parasteatoda, establishing the wide distribution of latrotoxins across the mega-diverse spider family Theridiidae. Across black widow species, α-latrotoxin shows ≥94% nucleotide identity and variability consistent with purifying selection. Multiple codon and branch-specific estimates of the nonsynonymous/synonymous substitution rate ratio also suggest a long history of purifying selection has acted on α-latrotoxin across Latrodectus and Steatoda. However, α-latrotoxin is highly divergent in amino acid sequence between these genera, with 68.7% of protein differences involving non-conservative substitutions, evidence for positive selection on its physiochemical properties and particular codons, and an elevated rate of nonsynonymous substitutions along α-latrotoxin’s Latrodectus branch. Such variation likely explains the efficacy of red-back spider, L. hasselti, antivenom in treating bites from other Latrodectus species, and the weaker neurotoxic symptoms associated with Steatoda and Parasteatoda bites. Long-term purifying selection on α-latrotoxin indicates its functional importance in black widow venom, even though vertebrates are a small fraction of their diet. The greater differences between Latrodectus and Steatoda α-latrotoxin, and their relationships to invertebrate-specific latrotoxins, suggest a shift in α-latrotoxin toward increased vertebrate toxicity coincident with the evolution of widow spiders.
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multiple recombining loci encode masp1 the primary constituent of dragline silk in widow spiders Latrodectus theridiidae
Molecular Biology and Evolution, 2008Co-Authors: Nadia A Ayoub, Cheryl Y. HayashiAbstract:: Spiders spin a functionally diverse array of silk fibers, each composed of one or more unique proteins. Most of these proteins, in turn, are encoded by members of a single gene family thought to have arisen through duplication and divergence of an ancestral silk gene. Because of its remarkable mechanical properties, orb weaver dragline silk, a composite of 2 proteins (MaSp1 and MaSp2), is the best studied. Here, we demonstrate that multiple loci encode MaSp1 in widow spiders (Latrodectus). Because these copies may be the result of more recent duplication events than those leading to the currently recognized silk gene paralogs, they offer insight into the early evolutionary fate of silk gene duplicates. In addition to 3 presumed functional MaSp1 loci in Latrodectus hesperus (Western black widow) and Latrodectus geometricus (brown widow) genomes, we find a MaSp1 pseudogene in L. hesperus, demonstrating the potential for unrecognized extinction of silk gene paralogs. We also document recombination events among L. hesperus MaSp1 loci and between Latrodectus MaSp1 loci and MaSp2. This result supports the hypothesis that concerted evolution occurs not only within an individual silk gene but also among silk gene paralogs. One of the L. geometricus MaSp1 copies encodes a protein that has diverged in amino acid composition and potentially converged on the secondary structure of MaSp2. Based on the presence of multiple MaSp1 loci and the phylogenetic distribution of MaSp1 versus MaSp2, we propose that MaSp2 is derived from an ancestral MaSp1 duplicate. Finally, divergence has occurred in the upstream flanking sequences of the L. hesperus MaSp1 loci, the region most likely to contain regulatory motifs, providing ample opportunity for differential expression. However, the benefits associated with increased protein production may be the primary mechanism maintaining multiple functional MaSp1 copies in widow genomes.
Richard F Clark - One of the best experts on this subject based on the ideXlab platform.
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the treatment of black widow spider envenomation with antivenin Latrodectus mactans a case series
The Permanente Journal, 2011Co-Authors: G P Daubert, Richard F ClarkAbstract:Black widow spiders (Latrodectus mactans) are found throughout the US. Though bites are relatively uncommon, they pose a significant health problem with over 2500 reported to American poison control centers annually. Black widow spider bites cause a characteristic envenomation syndrome consisting of severe pain, muscle cramping, abdominal pain, and back pain. The significant pain associated with envenomation is often refractory to traditional analgesics. Antivenom (Antivenin Latrodectus mactans) is available and effective, but is often withheld because of a fear of acute hypersensitivity reactions. We report four cases of symptomatic black widow spider envenomation. One of the reported cases was managed without antivenom, and, in contrast, three were treated successfully with Antivenin Latrodectus mactans. We believe that these cases demonstrate safe and effective use of black widow antivenom. This article presents the rationale for use of antivenom in these cases, and a nonsystematic review of the pertinent literature.
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the safety and efficacy of antivenin Latrodectus mactans
Clinical Toxicology, 2001Co-Authors: Richard F ClarkAbstract:Latrodectus species of spiders are ubiquitous throughout the world. The United States is home to at least five varieties, and the North American native Latrodectus mactans can now be found around t...
Jessica E. Garb - One of the best experts on this subject based on the ideXlab platform.
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Molecular evolution of α-latrotoxin, the exceptionally potent vertebrate neurotoxin in black widow spider venom
Molecular biology and evolution, 2013Co-Authors: Jessica E. Garb, Cheryl Y. HayashiAbstract:Black widow spiders (members of the genus Latrodectus) are widely feared because of their potent neurotoxic venom. α-Latrotoxin is the vertebrate-specific toxin responsible for the dramatic effects of black widow envenomation. The evolution of this toxin is enigmatic because only two α-latrotoxin sequences are known. In this study, ∼4 kb α-latrotoxin sequences and their homologs were characterized from a diversity of Latrodectus species, and representatives of Steatoda and Parasteatoda, establishing the wide distribution of latrotoxins across the mega-diverse spider family Theridiidae. Across black widow species, α-latrotoxin shows ≥94% nucleotide identity and variability consistent with purifying selection. Multiple codon and branch-specific estimates of the nonsynonymous/synonymous substitution rate ratio also suggest a long history of purifying selection has acted on α-latrotoxin across Latrodectus and Steatoda. However, α-latrotoxin is highly divergent in amino acid sequence between these genera, with 68.7% of protein differences involving non-conservative substitutions, evidence for positive selection on its physiochemical properties and particular codons, and an elevated rate of nonsynonymous substitutions along α-latrotoxin’s Latrodectus branch. Such variation likely explains the efficacy of red-back spider, L. hasselti, antivenom in treating bites from other Latrodectus species, and the weaker neurotoxic symptoms associated with Steatoda and Parasteatoda bites. Long-term purifying selection on α-latrotoxin indicates its functional importance in black widow venom, even though vertebrates are a small fraction of their diet. The greater differences between Latrodectus and Steatoda α-latrotoxin, and their relationships to invertebrate-specific latrotoxins, suggest a shift in α-latrotoxin toward increased vertebrate toxicity coincident with the evolution of widow spiders.
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the black widow spider genus Latrodectus araneae theridiidae phylogeny biogeography and invasion history
Molecular Phylogenetics and Evolution, 2004Co-Authors: Jessica E. Garb, Alda Gonzalez, Rosemary G GillespieAbstract:The spider genus Latrodectus includes the widely known black widows, notorious because of the extreme potency of their neurotoxic venom. The genus has a worldwide distribution and comprises 30 currently recognized species, the phylogenetic relationships of which were previously unknown. Several members of the genus are synanthropic, and are increasingly being detected in new localities, an occurrence attributed to human mediated movement. In particular, the nearly cosmopolitan range of the brown widow, Latrodectus geometricus, is a suspected consequence of human transport. Although the taxonomy of the genus has been examined repeatedly, the recognition of taxa within Latrodectus has long been considered problematic due to the difficulty associated with identifying morphological features exhibiting discrete geographic boundaries. This paper presents, to our knowledge, the first phylogenetic hypothesis for the Latrodectus genus and is generated from DNA sequences of the mitochondrial gene cytochrome c oxidase subunit I. We recover two well-supported reciprocally monophyletic clades within the genus: (1) the geometricus clade, consisting of Latrodectus rhodesiensis from Africa, and its is sister species, the cosmopolitan L. geometricus, and (2) the mactans clade containing all other Latrodectus species sampled, including taxa occurring in Africa, the Middle East, Iberian Peninsula, Australia, New Zealand, and North and South America. Recovery of the geometricus and mactans clades is consistent with previous designations of species groups within the genus based on female genitalic morphology. All L. geometricus sampled, consisting of specimens from Africa, Argentina, North America, and Hawaii, were recovered as a strongly supported monophyletic group with minimal amounts of genetic divergence, corroborating the hypothesis that human transport has recently expanded the range of this species.
Silva Correa Carmen - One of the best experts on this subject based on the ideXlab platform.
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EFECTO DEL VENENO DE Latrodectus mactans EN LOS NIVELES PLASMÁTICOS DE ÓXIDO NÍTRICO Y EN EL COMPORTAMIENTO SEXUAL EN Oryctolagus cunniculus
UNIVERSIDAD NACIONAL DE TRUJILLO, 2014Co-Authors: Huari Marín Gloria, Jiménez Rodríguez Yhen, Julca Majo Alan, Lpoez Díaz Sandra, Llapo Miñano Andy, Mendoza Sicche Juan, Luis Reyna Martín, Becerra Urquizo Andrea, Guzmán Ruiz Liliana, Silva Correa CarmenAbstract:Objetivo: El objetivo del presente trabajo fue evaluar el efecto del veneno de Latrodectus mactans en los niveles plasmáticos de óxido nítrico y el comportamiento sexual de Oryctolagus cunniculus. Material y método: Se capturaron 10 especímenes de Latrodectus mactans en las inmediaciones del campus de la Universidad Nacional de Trujillo en lugares secos, abrigados y oscuros. Se adquirieron 7 especímenes machos y 7 hembras de Oryctolagus cunniculus a los que se inyectó 0.1 mL de veneno de araña. Se determinaron los niveles de óxido nítrico (NO) indirectamente por la conversión en nitritos (NO2-) y nitratos (NO3-) que son los principales productos de degradación del NO, por el método de Método de Griess. Se evaluó el comportamiento sexual teniendo en cuenta los siguientes parámetros: frecuencia de monta, frecuencia de intromisiones, latencia de monta, latencia de intromisiones y latencia post eyaculatoria. Resultados: Se observó que los niveles de NO aumentaron en promedio a 7.75µmol /ml con la administración de 0.1 ml del homogenizado de veneno de Latrodectus mactans (p < 0.05) comparados con la administración de 0.1 mL de Solución Salina Fisiológica (grupo blanco) que aumentó a 4.06µmol /ml en promedio (p < 0.05). En el comportamiento sexual se observó un aumento en la frecuencia de monta, frecuencia de intromisiones y disminución en la latencia de intromisiones y latencia post eyaculatoria (p < 0.05). Conclusiones: El veneno de Latrodectus mactans eleva en forma significativa los niveles plasmáticos de óxido nítrico en Oryctolagus cunniculus, además estimula el comportamiento sexual de dichos especímenes. Palabras clave: Latrodectus mactans, Óxido nítrico, comportamiento sexual.
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efecto del veneno de Latrodectus mactans en los niveles plasmaticos de oxido nitrico y en el comportamiento sexual en oryctolagus cunniculus effect of Latrodectus mactans venom in plasma nitric oxide levels and sexual behavior in oryctolagus cunnicul
2014Co-Authors: Huari Marín Gloria, Jiménez Rodríguez Yhen, Julca Majo Alan, Mendoza Sicche Juan, Luis Reyna Martín, Lopez Diaz Sandra, Becerra Urquiza Andrea, Guzman Ruiz, Silva Correa CarmenAbstract:Objective: The aim of this study was to evaluate the effect of Latrodectus mactans venom in plasma levels of nitric oxide and the sexual behavior of Oryctolagus cunniculus. Methods: 10 specimens of L. mactans were caught near the campus of the National University of Trujillo from dry, warm and dark places. Seven male and seven female specimens of Oryctolagus cunniculus were purchased. The levels of nitric oxide (NO) was determined indirectly (Griess method) by conversion to nitrite (NO2 - ) and nitrate (NO3 - ) which are the main products of degradation of NO. Sexual behavior was evaluated through of parameters as mount frequency, intromission frequency, mount latency, intromission latency and post-ejaculatory latency. Results: Nitric oxide levels increased an average of 7.75 µmol / ml with administration of 0.1 ml of homogenized venom from Latrodectus mactans (p < 0.05) compared with administration of 0.1 mL of physiologic sodium chloride (white group) in which levels of nitric oxide increased only at 4.06 µmol/ml on average (p<
Andrew A Monte - One of the best experts on this subject based on the ideXlab platform.
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black widow spider Latrodectus mactans antivenom in clinical practice
Current Pharmaceutical Biotechnology, 2012Co-Authors: Andrew A MonteAbstract:Black widow spider (Latrodectus mactans) envenomation has been recognized since antiquity. The syndrome, latrodectism, is characterized by painful muscle rigidity and autonomic disturbances such as tachycardia, hypertension, and diaphoresis. Symptoms typically last for 1-3 days. Treatment has ranged from local folk remedies to administration of specific antivenom. Opioid analgesics combined with muscle relaxants, such as benzodiazepines, are only effective at symptomatic and temporary control. Antivenom is by far the most efficacious therapy available based on symptom resolution, need for subsequent therapy, and hospital admission rates. Fear of allergic type reactions from antivenom administration has limited its use in the United States. A new purified F(ab)2 fragment Latrodectus mactans antivenom, Analatro®, is currently undergoing clinical trials. The product is expected to have similar efficacy and be associated with fewer adverse reactions when compared to the currently available partially purified whole IgG Merck product. This shift in the risk-benefit analysis may ultimately lead to more antivenom administration in significantly envenomated patients.