Gill‐derived glands in species of Astyanax (Teleostei: Characidae)

The presence of a gill‐derived gland is herein reported for the first time in males of species of Astyanax and related genera; they are described through histological cuts and SEM. The gill‐derived glands described for the Characidae, when fully developed, present a similar structure in different species. The main external feature of gill‐derived glands is the fusion of anteriormost gill filaments on the ventral branch of first gill arch. This fusion is caused by squamous stratified epithelial tissue that covers adjacent filaments, forming a series of chambers. In the region where the gill‐derived gland develops, the secondary lamellae of the gill filaments are much reduced or completely atrophied being characterized by the presence of glandular cells forming nests.     

Expression of Secretogranin III in Chicken Endocrine Cells: Its Relevance to the Secretory Granule Properties of Peptide Prohormone Processing and Bioactive Amine Content

The expression of secretogranin III (SgIII) in chicken endocrine cells has not been investigated. There is limited data available for the immunohistochemical localization of SgIII in the brain, pituitary, and pancreatic islets of humans and rodents. In the present study, we used immunoblotting to reveal the similarities between the expression patterns of SgIII in the common endocrine glands of chickens and rats. The protein–protein interactions between SgIII and chromogranin A (CgA) mediate the sorting of CgA/prohormone core aggregates to the secretory granule membrane. We examined these interactions using co-immunoprecipitation in chicken endocrine tissues. Using immunohistochemistry, we also examined the expression of SgIII in a wide range of chicken endocrine glands and gastrointestinal endocrine cells (GECs). SgIII was expressed in the pituitary, pineal, adrenal (medullary parts), parathyroid, and ultimobranchial glands, but not in the thyroid gland. It was also expressed in GECs of the stomach (proventriculus and gizzard), small and large intestines, and pancreatic islet cells. These SgIII-expressing cells co-expressed serotonin, somatostatin, gastric inhibitory polypeptide, glucagon-like peptide-1, glucagon, or insulin. These results suggest that SgIII is expressed in the endocrine cells that secrete peptide hormones, which mature via the intragranular enzymatic processing of prohormones and physiologically active amines in chickens.     

Respiratory metabolism of salivary glands during the late larval and prepupal development of Drosophila melanogaster

During the late larval period, the salivary glands (SG) of Drosophila show a cascade of cytological changes associated with exocytosis and the expectoration of the proteinaceous glue that is used to affix the pupariating larva to a substrate. After puparium formation (APF), SG undergo extensive cytoplasmic vacuolation due to endocytosis, vacuole consolidation and massive apocrine secretion. Here we investigated possible correlations between cytological changes, the puffing pattern in polytene chromosomes and respiratory metabolism of the SG. The carefully staged SG were explanted into small amounts (1 or 2 μl) of tissue culture medium. The respiratory metabolism of single or up to 3 pairs of glands was evaluated by recording the rate of O₂ consumption using a scanning microrespirographic technique sensitive to subnanoliter volumes of the respiratory O₂ or CO₂. The recordings were carried out at times between 8 h before pupariation (BPF), until 16 h APF, at which point the SG completely disintegrate. At the early wandering larval stage (8 h BPF), the glands consume 2 nl of O₂/gland/min (=2500 μl O₂/g/h). This relatively high metabolic rate decreases down to 1.2–1.3 nl of O₂ during the endogenous peak in ecdysteroid concentration that culminates around pupariation. The metabolic decline coincides with the exocytosis of the proteinaceous glue. During and shortly after puparium formation, which is accompanied cytologically by intense vacuolation, O₂ consumption in the SG temporarily increases to 1.6 nl O₂/gland/min. After this time, the metabolic rate of the SG decreases downward steadily until 16 h APF, when the glands disintegrate and cease to consume oxygen. The SG we analyzed from Drosophila larvae were composed of 134 intrinsic cells, with the average volume of one lobe being 37 nl. Therefore, a single SG cell of the wandering larva (with O₂ consumption of 2 nl/gland/min), consumes each about 16 pl of O₂/cell/min. A simultaneous analysis of the rate of protein and RNA synthesis in the SG shows a course similar to that found in respiratory metabolism.     

Sternal gland structures in males of bean flower thrips,Megalurothrips sjostedti,and Poinsettia thrips,Echinothrips americanus,in comparison with those of western flower thrips,Frankliniella occidentalis (Thysanoptera: Thripidae)

Sternal pores are important features for identification of male thrips, especially within the subfamily Thripinae. They vary in shape, size and distribution even between species of one genus. Their functional role is speculated to be that of sex- and/or aggregation pheromone production. Yet, sexual aggregations are not reported in Echinothrips americanus, known to have sternal pores, while we observed aggregations in Megalurothrips sjostedti, previously reported to lack them.We examined the sternal glands and pores of the thripine species E. americanus and M. sjostedti males, in comparison with those of Frankliniella occidentalis using light microscopy, as well as scanning and transmission electron microscopy. Pore plates of F. occidentalis were ellipsoid and medial on sternites III–VII, while in E. americanus they were distributed as multiple micro pore plates on sternites III–VIII. In M. sjostedti they appeared as an extremely small pore in front of the posterior margin of each of sternites IV–VII. Pore plate and pore plate area were distributed similarly on sternites III–VII in F. occidentalis. However, in E. americanus the total pore plate area increased significantly from sternites III to VIII. Ultrastructure of cells associated with sternal glands showed typical characteristics of gland cells that differ in size, shape and number. The function of sternal glands is further discussed on the basis of morphological comparisons with other thrips species.     

Morphology and morphogenesis of a freshwater ciliate, Epistylis chlorelligerum Shen, 1980 (Ciliophora, Peritrichia)

An oligohalobic peritrichous ciliate, Epistylis chlorelligerum Shen, 1980, was collected from a ditch in Hangzhou, China. The morphology, oral infraciliature, and morphogenesis of the species were studied using living and protargol-impregnated specimens. Zooids of E. chlorelligerum are 160-230 × 50-60 μm in vivo, and characterized by green-colored endoplasm containing symbiotic algae. The oral infraciliature presents a well-developed filamentous reticulum linked to the circular fiber of the cytostome; the outer two rows of P3 extend adstomally over P1 and usually enfold it. During binary fission, one daughter cell inherits most part of the old buccal apparatus and the reorganized haplokinety and germinal kinety (Hk' and G'), and new buccal apparatus of the other daughter cell is mostly developed from the original germinal kinety (G) and haplokinety (Hk): new peniculi 2, 3 (2P2, 2P3), new haplokinety (2Hk), and new germinal kinety (2G) are formed from G, while the new peniculus 1 (2P1) and its peristomial extention (2Pk) originate from Hk. The epistomial membrane can be observed until the two sets of buccal apparatus begin to separate from each other.     

Functional morphology of the metapleural gland in workers of the ant Crematogaster inflata (Hymenoptera,Formicidae)

Abstract. Workers of Crematogaster inflata possess the largest metapleural glands (relative to body size) known among ants, with reservoirs extending anteriorly up to the junction between the pro‐ and the mesothorax, and with over 1400 secretory cells on both sides together. This large secretory capacity is related to the gland's defensive function, which, in members of this species, is directed against larger arthropod and vertebrate enemies, and apparently not against microorganisms, in contrast to other ants, where the gland produces antibiotics. The gland is not equipped with any direct musculature. Secretion release is probably caused by contraction of the oblique longitudinal thorax muscles or by passive expulsion caused by external pressure.     

Ontogenetic changes in the chemistry and morphology of oil glands in Hermannia convexa (Acari: Oribatida)

As a first example for the chemistry of oil gland secretions in the Hermannioidea (one of the three superfamilies of desmonomatan Oribatida), the oil gland secretion of Hermannia convexa was investigated by gas chromatography–mass spectrometry. Hexane extracts of all juvenile stages showed a multicomponent chromatographic pattern, mainly consisting of well-known oil gland secretion components such as neral, geranial, -acaridial and the unsaturated C17-hydrocarbons, 6,9-heptadecadiene and 8-heptadecene. The secretion profiles of juveniles varied slightly between samples of two different collections, namely in the presence of -acaridial and 8-heptadecene. Furthermore, a minor component, identified as 1,8-cineole (= eucalyptol) and hitherto not known from oil gland secretions of other species, was recorded in both juvenile and adult extracts. In adult profiles, 1,8-cineole, in low amounts, represented the only detectable component; thus, their profiles fundamentally differed from those of juveniles. A subsequent histological investigation revealed well developed oil glands in all juvenile stages, but degenerated oil glands in adults, consistent with the chemical data. So far, apart from H. convexa, degeneration of oil glands in the course of ontogenetic development is only known from a brachypylid species; on the other hand, chemical oil gland-polymorphism between juveniles and adults may occur in closely related Nothridae while it does not occur in oil glands of early- and middle-derivative Oribatida (Parhyposomata, Mixonomata, trhypochthoniid Desmonomata), nor in astigmatid mites.This revised version was published online in May 2005 with a corrected cover date.