Ducts of the labral glands of Leptestheria dahalacensis (Crustacea: Branchiopoda: Spinicaudata)

Fine structure of the silk gland in the mite Ornithocheyletia sp. (Prostigmata, Cheyletidae)

Silk spinning is widely-spread in trombidiform mites, yet scarse information is available on the morphology of their silk glands. Thus this study describes the fine structure of the prosomal silk glands in a small parasitic mite, Ornithocheyletia sp. (Cheyletidae). These are paired acinous glands incorporated into the podocephalic system, as typical of the order. Combined secretion of the coxal and silk glands is released at the tip of the gnathosoma. Data obtained show Ornithocheyletia silk gland belonging to the class 3 arthropod exocrine gland. Each gland is composed of seven pyramidal secretory cells and one ring-folded intercalary cell, rich in microtubules. The fine structure of the secretory cells points to intensive protein synthesis resulted in the presence of abundant uniform secretory granules. Fibrous content of the granules is always subdivided into several zones of two electron densities. The granules periodically discharge into the acinar cavity by means of exocytosis. The intercalary cell extends from the base of the excretory duct and contributes the wall of the acinar cavity encircling the apical margins of the secretory cells. The distal apical surface of the intercalary cell is covered with a thin cuticle resembling that of the corresponding cells in some acarine and myriapod glands. Axon endings form regular synaptic structures on the body of the intercalary cell implying nerve regulation of the gland activity.

Congruence between male upper lip morphology and molecular phylogeny in Parapolycope (Ostracoda), with two new species from Korea

The ostracod genera Parapolycope Klie, 1939 and Kliecope Tanaka, Tsukagoshi & Karanovic, 2014 have a sexually dimorphic upper lip, and males use their lip during courtship. Here we study the male upper lip of 14 species in order to find homologous structures. For this purpose, the lip is divided into six homologous parts, determined by their relative position on the lip and the lip’s position in relation to other body parts. We found that the distal part (‘c’) is the most variable across taxa, probably due to high sexual selection. Six characters of the male upper lip are used in our cladistic analysis, along with another 12, in order to study phylogenetic relationships between Parapolycope species from East Asia. In addition, 18S rRNA is used to reconstruct molecular phylogeny and test the congruence between morphological and molecular data. The recovered topology on all obtained trees is almost identical, emphasising the importance of the male upper lip morphology in interpreting phylogenetic relationships in this peculiar ostracod group. Parapolycope viriosa, sp. nov. and P. widoensis, sp. nov. from marine interstitial habitats in South Korea are described here. To aid further identification of the 12 East Asian Parapolycope species we provide a taxonomic key.

Olfactory specific chymotrypsin-like serine protease from the aesthetasc tegumental gland of the lobster, Homarus americanus

Numerous proteases and protease inhibitors are expressed in the lobster olfactory organ. One of these proteases, olfactory enriched transcript 03 (OET-03), is particularly interesting because its mRNA is expressed only in one cell type of the olfactory organ of the American lobster, Homarus americanus. We have obtained a full-length cDNA clone of OET-03. The predicted amino acid sequence is equally divided between a novel N-terminal domain and a conserved serine protease catalytic domain at the C-terminus. Heterologous expression in HEK293 cells allowed protease assays demonstrating that OET-03 cleaved a specific serine protease substrate, N-alpha benzoyl-L-arginine p-nitroanilide, but did not cleave a substrate of metalloproteases and cysteine proteases. OET-03 protease activity was significantly inhibited by the chymotrypsin-like protease inhibitor, tosyl-L-phenylalanine chloromethyl ketone, but not by the general protease inhibitor, phenylmethylsulfonyl fluoride. Immunoreactivity for OET-03 was detected only in the cells previously shown to contain OET-03 mRNA. The cytoplasm of these cells was filled with enlarged smooth endoplasmic reticulum (a characteristic of secretory cells) that appeared to expand into large electron-translucent areas at the ventral end of the cell. The ventral ends of these secretory cells were apposed to phalloidin-labeled triangular structures reminiscent of the beginnings of the ducts of crustacean tegumental glands. This putative gland was found only in association with the aesthetasc sensory units of the olfactory organ, hence the name, aesthetasc tegumental gland.