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Silk Gland (silk + gland)

Distribution by Scientific Domains

Life Sciences	53%
Chemistry	46%

Kinds of Silk Gland

anterior silk gland

Selected Abstracts

Microstructure of the silk spigots of the green crab spider Oxytate striatipes (Araneae: Thomisidae)

ENTOMOLOGICAL RESEARCH, Issue 3 2006
Myung-Jin MOON
Abstract The genus Oxytate L. Koch, 1878 comprises a homogeneous group of nocturnal crab spiders that have silk apparatuses even though they do not spin webs to trap prey. We examined the microstructure of the silk spinning apparatus of the green crab spider Oxytate striatipes, using field emission scanning electron microscopy. The silk glands of the spider were classified into three types: ampullate, pyriform and aciniform. The spigots of these three types of silk gland occur in both sexes. Two pairs of major ampullate glands send secretory ductules to the anterior spinnerets, and another two pairs of minor ampullate glands supply the median spinnerets. In addition, the pyriform glands send ductules to the anterior spinnerets (45 pairs in females and 40 pairs in males), and the aciniform glands feed silk into the median (9,12 pairs in females and 7,10 pairs in males) and the posterior (30 pairs in both sexes) spinnerets. The spigot system of O. striatipes is simpler and more primitive than other wandering spiders: even the female spiders possess neither tubuliform glands for cocoon production nor triad spigots for web-building. [source]

Presence of membrane ecdysone receptor in the anterior silk gland of the silkworm Bombyx mori

FEBS JOURNAL, Issue 15 2004
Mohamed Elmogy
Nongenomic action of an insect steroid hormone, 20-hydroxyecdysone (20E), has been implicated in several 20E-dependent events including the programmed cell death of Bombyx anterior silk glands (ASGs), but no information is available for the mode of the action. We provide evidence for a putative membrane receptor located in the plasma membrane of the ASGs. Membrane fractions prepared from the ASGs exhibit high binding activity to [3H]ponasterone A (PonA). The membrane fractions did not contain conventional ecdysone receptor as revealed by Western blot analysis using antibody raised against Bombyx ecdysone receptor A (EcR-A). The binding activity was not solubilized with 1,m NaCl or 0.05% (w/v) MEGA-8, indicating that the binding sites were localized in the membrane. Differential solubilization and temperature-induced phase separation in Triton X-114 showed that the binding sites might be integrated membrane proteins. These results indicated that the binding sites are located in plasma membrane proteins, which we putatively referred to as membrane ecdysone receptor (mEcR). The mEcR exhibited saturable binding for [3H]PonA (Kd = 17.3 nm, Bmax = 0.82 pmol·mg,1 protein). Association and dissociation kinetics revealed that [3H]PonA associated with and dissociated from mEcR within minutes. The combined results support the existence of a plasmalemmal ecdysteroid receptor, which may act in concert with the conventional EcR in various 20E-dependent developmental events. [source]

Characterization of a novel silkworm (Bombyx mori) phenol UDP-glucosyltransferase

FEBS JOURNAL, Issue 3 2002
Teresa Luque
Sugar conjugation is a major pathway for the inactivation and excretion of both endogenous and exogenous compounds. We report here the molecular cloning and functional characterization of a phenol UDP-glucosyltransferase (UGT) from the silkworm, Bombyx mori, which was named BmUGT1. The complete cDNA clone is 1.6 kb, and the gene is expressed in several tissues of fifth-instar larvae, including fat body, midgut, integument, testis, silk gland and haemocytes. The predicted protein comprises 520 amino acids and has ,,30% overall amino-acid identity with other members of the UGT family. The most conserved region of the protein is the C-terminal half, which has been implicated in binding the UDP-sugar. BmUGT1 was expressed in insect cells using the baculovirus expression system, and a range of compounds belonging to diverse chemical groups were assessed as potential substrates for the enzyme. The expressed enzyme had a wide substrate specificity, showing activity with flavonoids, coumarins, terpenoids and simple phenols. These results support a role for the enzyme in detoxication processes, such as minimizing the harmful effects of ingested plant allelochemicals. This work represents the first instance where an insect ugt gene has been associated with a specific enzyme activity. [source]

Function of a TGF-, inducible nuclear protein in the silk gland in Bombyx mori

INSECT MOLECULAR BIOLOGY, Issue 2 2009
J-L. Wang
Abstract A TGF-, inducible nuclear protein 1 (BmTINP1) was cloned from silkworm, Bombyx mori. Polyclonal antibodies against BmTINP1 were produced and subsequently used in immunoblotting and immunohistochemistry analyses. The immunoblotting analyses demonstrated that BmTINP1 was specifically expressed in the anterior silk gland (ASG) and the middle silk gland (MSG) but not in the posterior silk gland (PSG). There were two bands that suggested the existence of an isoform of BmTINP1. The expression profiles of BmTINP1 in ASGs and MSGs were similar, and they manifested a high level of expression throughout the period during which silk gland grew exponentially. Immunohistochemistry results revealed that BmTINP1 was translocated from the nucleus into the cytoplasm when larvae developed from the 4th-HCS into the 5th instar. 20-hydroxyecdysone (20E) promotes the translocation, while the methoprene [a juvenile hormone (JH) analog] restrains the process. Our findings indicate that BmTINP1 is involved in silk produce along with the rapid growth of ASGs and MSGs during the last instar larvae, and the process could be regulated by hormones via control of BmTINP1 translocation from the nucleus to the cytoplasm. [source]

Report on construction of gene-targeting vector for homologous recombination and transformation in silkworm, Bombyx mori L.

JOURNAL OF APPLIED ENTOMOLOGY, Issue 3 2005
Y.-G. Miao
Abstract:, This paper reports the methods of construction of gene-targeting vector for transformation of silkworm, Bombyx mori L. The genomic DNA was isolated from the posterior silk gland of the fifth-instar silkworm larvae. The short fragment (0.5 kb) and long fragment (5 kb) of the fibroin light-chain gene were obtained by polymerase chain reaction (PCR) analysis with special primers and genome DNA as templates and then recombined with pBlueselect vector into pBs-FS-FL. The target green flourescent protein (GFP) gene, was derived from pGEP-1 vector and recombined with pUC19 vector into pUCG vector. GFP was recovered after cutting with restriction endonucleases, PstI and BamHI. Finally, GFP was recombined with pBs-FS-FL into gene-targeting vector, pBs-FS-GFP-FL. [source]

Comparative analysis of two biliproteins, BP1 and BP2, from haemolymph of cabbage white butterfly, Pieris rapae

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 4 2006
Chi Won Choi
Abstract Two blue-pigment binding proteins, BP1 and BP2, are present in larval and pupal haemolymph of cabbage white butterfly, Pieris rapae, and fluctuate in expression during development. Both BP1 and BP2 are found in pupal haemolymph in varying proportions as well as in adult haemolymph, while only small amounts of BP2 are found in larval haemolymph. BPs are separated by 75% ammonium sulfate, and then purified effectively by ion exchange column chromatography and preparative gel electrophoresis. It was shown that BP1 and BP2 have molecular masses of 20,244 and 19,878 Da, and isoelectric points of 7.0 and 6.8, respectively. Considering their amino acid compositions and N-terminal amino acid sequences, the two proteins are almost identical except the first N-terminal amino acid. The first amino acid of BP1 is asparagine, whereas the initial residue of BP2 is aspartic acid. Anti-BP1 cross-reacts with BP2, indicating that they have immunological homogeneity. Western blotting analyses revealed that only BP1 was present in the larval tissues such as fat body, integument, muscle, and hindgut. However, BP1 was not found in midgut, Malphigian tubules, and silk gland. BP1 was also present in the protein bodies, and both cuticle and hemocoel sides of larval epidermis cells by the transmission electron microscopic observation. The information in this report will facilitate studies on the molecular biology and biological significance of insect BPs. Arch. Insect Biochem. Physiol. 61:220,230, 2006. © 2006 Wiley-Liss, Inc. [source]

Fine Structural Analysis of the Silk Apparatus in the Funnel-web Spider, Agelena limbata (Araneae: Agelenidae)

ENTOMOLOGICAL RESEARCH, Issue 4 2002
Jong-Gu PARK
ABSTRACT Silk apparatus of the funnel-web spider, Agelena limbata was located at the ventral end of the abdominal part, and was composed of internal silk glands and external spinnerets. Among the three pairs of spinnerets, the posterior pairs were highly elongated along the body axis. By the light and electron microscopic inspections, it was found that four types of silk glands were connected through the typical spinning tubes of each spinneret. Anterior spinnerets comprise 2 pairs of the ampullate and 125 to 150 pairs (female) or 110 to 114 (male) of pyriform glands. Another 2 pairs of ampullate glands in both sexes, 5 to 8 pairs of tubuliform glands in females, and 20 to 26 pairs (female) or 15 to 17 pairs (male) of aciniform glands were connected on the median spinnerets. Additional 8 to 10 pairs of tubuliforms in female and 41 to 53 pairs (female) or 27 to 32 pairs (male) of aciniform glands were on the posterior spinnerets, respectively. While the ampullate and tubuliform glands were connected with the spigot-type spinning tubes, the pyriform and aciniform glands with that of spool-type tubes. It has been also revealed that the tubuliform glands were only observed in female spiders, however the flagelliform and aggregate glands which had the function of adhesive thread production in orb-web spiders were not observed at both sexes of this spiders. [source]

Presence of membrane ecdysone receptor in the anterior silk gland of the silkworm Bombyx mori

Ace2, rather than ace1, is the major acetylcholinesterase in the silkworm, Bombyx mori

INSECT SCIENCE, Issue 4 2009
Hui-Juan Chen
Abstract, Two acetylcholinesterase (ace) genes have been reported in many insect species. In pests such as Helicoverpa assulta and Plutella xylostellas, ace1 gene encodes the predominant synaptic enzyme that is the main target of organophosphorus (OP) and carbamate pesticides. It has been reported that pesticide selection has an impact on the ace gene evolution. The domesticated silkworm, Bombyx mori, also has two ace genes. We studied ace gene expression and enzyme activities in silkworm as this has not faced pesticide selection over the past decades. The expression levels of two ace genes, Bm- ace1 and Bm- ace2, were estimated by quantitative real-time polymerase chain reaction. Bm- ace2 was expressed more highly than Bm- ace1 in all tested samples of different developmental stages or tissues, suggesting ace2, rather than ace1, is the major type of acetylcholinesterase (AChE) in Bombyx mori. This is inconsistent with the aforementioned lepidopterons agricultural pests, partly be due to the widespread use of pesticides that may induce high expression of the ace1 gene in these pests. Besides high expression in the head, Bm- ace1 also expresses highly in the silk glands and Bm- ace2 is abundant in the germline, implying both ace genes may have potential non-hydrolytic roles in development. Furthermore, we found that the mRNA levels of two ace genes and their ratios (ace2/ace1) change day to day in the first and third instars. This challenges the conventional method of estimating enzymatic activity using crude extract as an enzyme solution, as it is a mixture of AChE1 and AChE2. An efficient and simple method for separating different AChEs is necessary for reliable toxicological analyses. [source]

The expression patterns of a eukaryotic initiation factor 3 subunit H in the silk glands in Bombyx mori

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2010
Jia-Lin Wang
Abstract Eukaryotic initiation factor 3 subunit H has been characterized in many organisms, and it has been found to play many roles including help regulate translation initiation. In this work, we studied the tissue distribution and expression profiles of Bombyx mori (B. mori) eIF3 subunit H (BmeIF3h). BmeIF3h was prominently expressed in silk glands, with anterior silk glands (ASGs), middle silk glands (MSGs), and posterior silk glands (PSGs) all expressing BmeIF3h. The expression levels of BmeIF3h in MSGs and PSGs were higher than that in ASGs during 0 d and 2 d of the 5th instar larvae. The expression levels of BmeIF3h in MSGs and PSGs were up-regulated once the silk glands began to synthesize silk protein during the feeding stage of the 4th instar larvae. Immunohistochemistry showed that BmeIF3h was distributed in the cytoplasm of MSGs cells and in both the nucleus and the cytoplasm of PSGs cells. These data suggest that BmeIF3h had different action behaviors in the MSGs and PSGs related to the production of the silk glue proteins and silk fibre proteins, respectively. © 2010 Wiley Periodicals, Inc. [source]