Ultrastructural modifications of the glandular epithelium of the receptaculum seminis in Thermobia domestica (Insecta: Thysanura) during the moulting period

Summary The wall of the receptaculum seminis of Thermobia domestica is composed of numerous glandular units, each with four enveloping cells (denoted 1 to 4) separated by ordinary epithelial cells and associated with a cuticular apparatus. During the moulting periods, which continue to occur in the adult stage, these cells undergo a series of transformations. Just before apolysis there is a dedifferentiation of numerous cytoplasmic organelles, but no mitosis has been observed. When the intima lifts off, the apical system of each glandular unit, i.e. the distal parts of the C2 and C3 cells surrounding the end apparatus, is also eliminated. Then at the apex of each glandular unit, a new ductule is formed in the cavity of which a long ciliary process grows up from cell C1. Finally comes the phase of cuticle formation, i.e., epicuticle for the ductules, epi-and endocuticle for the intima lining the central cavity of the receptaculum. Various cell types participate in secretion of cuticle, the ciliary cells (C1) being responsible for the formation of the porous end apparatus. At ecdysis almost all of the new intima has been secreted and the apical systems are once more differentiated. These transformations are compared with those recently described in other exocrine glands of arthropods, e.g., tegumentary glands and accessory glands of the genital ducts.     

Regulation by the H-2 gene complex of delayed type hypersensitivity

Identity at the major histocompatibility complex (MHC) was essential for successful transfer of delayed type hypersensitivity (DTH) in mice. The regions of the MHC involved differed according to the antigen used for sensitization. In the case of fowl gamma globulin (FGG), identity atI-A was necessary, whereas with dinitrofluorobenzene (DNFB), identity at theK, I, orD region was sufficient. These different genetic constraints probably reflect differences in the mechanisms by which antigens are presented to T lymphocytes. Cells from sensitized (CBA×C57BL)F₁ mice transferred DTH to FGG into parental-strain mice, but transfer was more effective in C57BL than in CBA with the same cell dose. This phenomenon is governed by the MHC, since there was better transfer intoH-2 ^b than intoH-2 ^k mice, regardless of their backgrounds. It may reflect the activity of an Ir gene-dependent process. Cells of one genotype (e.g., CBA), sensitized in chimeric mice derived from two MHC-incompatible strains (CBAC57BL), transferred DTH to both strains. These results do not support the notion that the genetic constraint observed in DTH transfer may be a result of the necessity for sensitized T and stimulator cells to match an identical MHC-coded cell interaction molecule. Rather, they favor the hypothesis that T cells recognize antigen, not as a naked determinant, but in close association with products of genes of the MHC.     

Earthworm coelomocytes in vitro

Summary Contamination and low viability of earthworm coelomocytes in tissue culture have delayed in vitro studies. Using penicillin, streptomycin, tetracycline and Amphotericin B,Lumbricus terrestis coelomocytes were maintained viable and uncontaminated for 10 days at 15°C in medium L-15 supplemented with 5 to 10% fetal bovine serum. The coelomocytes survived for at least 10 days with 85% viability as assessed by trypan blue exclusion assays and phagocytosis of heat-killed yeast. Studies on the thymidine uptake, however, were negative. With the involvement of coelomocytes in tissue graft rejection, in vitro techniques can now be applied to study their capacity in the immune response. Supported in part by USPHS Research Grant 1 RO 1 HD09333-01 to E. L. Cooper.     

Amylolytic enzymes from Aspergillus hennebergi (A. niger Group): Purification and characterization of amylases from solid and liquid cultures

Two glucoamylases (I and II) were produced during solid-state culture of Aspergillus hennebergi (A. niger group) on cassava meal, whereas one glucoamylase and one alpha-amylase were synthesized by the mould in liquid culture. These glucoamylases were acidic proteins with thermotolerant activities. Glucoamylase I was not a glycoprotein, but glucoamylase II and the glucoamylase from liquid cultures contained 15% of sugars. The alpha-amylase was significantly less thermotolerant and of smaller molecular weight. The influence of culture conditions on the production of different amylases by the same Aspergillus strain on the same substrate is discussed.     

Synergistic Regulation of Cytosolic Ca2+ Concentration in Mouse Astrocytes by NK1 Tachykinin and Adenosine Agonists

The effects on cytosolic Ca2+ concentration of 2-chloroadenosine and [L-Pro9]-substance P, a selective agonist of NK1 receptors, were investigated on astrocytes from embryonic mice in primary culture. Cells responded to [L-Pro9]-substance P with a transitory increase in cytosolic Ca2+ which was of shorter duration when external Ca2+ was removed. A transient response to 2-chloroadenosine alone occurred. When simultaneously applied, [L-Pro9]-substance P and 2-chloroadenosine evoked a prolonged elevation of cytosolic Ca2+ (up to 30 min). This phenomenon was dependent on the presence of extracellular Ca2+, but insensitive to dihydropyridines, La3+, and Co2+, excluding the implication of voltage-operated Ca2+ channels. Arachidonic acid also induced a sustained elevation of cytosolic Ca2+, but did not increase further the response evoked by [L-Pro9]-substance P and 2-chloroadenosine. The activation of protein kinase C by a diacylglycerol analogue mimicked the effect of [L-Pro9]-substance P in potentiating the 2-chloroadenosine-evoked response. Like 2-chloroadenosine, pinacidil, which hyperpolarizes the cells by opening K+ channels, prolonged the elevation of cytosolic Ca2+ concentration induced by [L-Pro9]-substance P. Conversely, depolarization with 50 mM KCl canceled the effects of either pinacidil or 2-chloroadenosine applied with [L-Pro9]-substance P. Pertussis toxin pretreatment suppressed all the effects induced by 2-chloroadenosine.     

The use of photosynthesis inhibitor (DCMU) for in situ metabolic and primary production studies on soft bottom benthos

A selective chemical photosynthesis inhibitor, DCMU (Dichorophenyl-dimethylurea), dissolved in DMSO (Dimethyl sulfoxide) was substituted for the dark incubation method commonly used to measure the oxygen consumption in metabolic and primary production studies. We compared oxygen fluxes during light incubations with DCMU and dark incubations procedure, on soft bottom benthos. For this purpose, we studied the effects of different DCMU concentrations. A concentration of 5 · 10^–5 mol l^–1 inside a clear incubation enclosure completely inhibits photosynthesis without affecting the metabolism of soft bottom benthos.