Common antigenic determinants in the glycoproteins of plants,molluscs and insects

An antiserum raised against -fructosidase isolated from the cell walls of suspension-cultured carrot cells cross-reacts with many plant proteins and hemocyanin ofHelix pomatia. The shared epitope appears to be a small complex glycan with a (1–2)-linked xylose residue attached to the -linked mannose residue of the core of an asparagine-linked oligosaccharide. There is strong cross-reactivity with the proteins of many seed plants, molluscs and insects, and no cross-reactivity with the proteins of fungi, algae, mosses, ferns, or any of the vertebrates tested. Xylose-containing glycans appear to increase the immunogenicity of the proteins to which they are attached, and we suggest that they may be responsible for some allergic responses of people that are repeatedly exposed to plant or insect proteins.     

Molecular topography of the Ca2+ — ATPase of sarcoplasmic reticulum

Summary The Ca²⁺ binding site region of the Ca²⁺ — ATPase of skeletal muscle sarcoplasmic reticulum was labeled with several fluorescent analogs of dicyclohexylcarbodiimide. As has been shown by Chadwick and Thomas [1, 2], in the absence of Ca²⁺ in the medium, labeling with the naphthyl carbodiimide results in the inhibition of enzyme activity. Further, Ca²⁺ occupancy of the high affinity sites of the enzyme protects against incorporation into the site(s). The fluorescent carbodiimide has been used to determine the depth of the site of label incorporation relative to the aqueous-bilayer interfaces by quenching studies using spin-labeled fatty acid derivatives. The series of quenchers used have their spin-label moiety located at different positions along the fatty acid chain. It was found that after suitable correction for differences in partitioning of the various derivatives, the order of quenching efficiency was 16 - > 12- > 10- > 7- > 5-NS, indicating that the naphthyl moiety is near the center of the bilayer. In contrast, quenching with the aqueous-restricted I^– indicated that the label is accessible from the external milieu, likewise for a presumed aqueous quencher, acrylamide. The aqueous quenchers accessibilities were altered upon Ca²⁺ binding to the ATPase. Quenching of the intrinsic fluorescence with the x-NS derivatives indicates that the ATPase tryptophan residues are primarily localized at the aqueous-membrane interfaces, with the order of quenching being 5- > 7- > 10- > 12- > 16-NS. The trp residue(s) which changes its fluorescence upon Ca²⁺ binding is shown to be near the membrane surface.     

Iodine binding and peroxidase activity in the endostyle of Salpa fusiformis,Thalia democratica,Dolioletta gegenbauri and Doliolum nationalis (Tunicata,Thaliacea)

Summary The protothyroid region in the endostyles of four species of tunicates was examined by means of autoradiography and cytochemistry, at both the light and electronmicroscopic levels. To reveal the primary binding site for iodine, autoradiography was carried out on endostylar tissue from animals that had been incubated with high activity ¹²⁵I^- over a short period of time. The specific iodine binding enzyme, a peroxidase, was traced by its reaction with DAB. In accordance with previous findings, the iodinebinding cells proved to be the same as those containing the peroxidase. There were also strong indications of a secondary uptake of iodinated compounds and subsequent release into the body fluid. Together with the ultrastructural features, the data provided strong evidence indicating that these cells constitute a protothyroid region, which partly functions as an endocrine organ, possibly homologous with the vertebrate thyroid gland. Since the number of zones varied between the species, the numeration of the protothyroid region also varied. However, in all the examined endostyles, the protothyroid region was seen to be situated dorsolaterally to the glandular regions of the endostyle concerned with food capture.     

Identification of minor tightly bound H1 histone subfractions which fail to cleave their initiator methionine

Groups of CBA mice were administered [³⁵S] methionine (1 mCi/mouse). Non-histone proteins, H1 and H1⁰ histones and nucleosomal core histones were isolated from different issues by selective extractions. The measurements of radioactivity of individual bands and autoradiography of dry gels were used to identify methionine-containing and methionine-free histone variants. H1A and H1B histone variants extracted with 5% perchloric acid were methionine-free. However, minor sub-fractions of these histones which are more tightly bound to DNA (and which can be extracted only with 0.25 N HC1) contained [³⁵S] methionine and did show a higher specific activity than methionine-containing nucleosomal hitones. Cyanogen Bromide reaction which destroys non-histone proteins and methionine-containing nucleosomal histones removes radioactivity but does not alter the position of methionine-containing H1 minor bands. This indicates that the radioactive methionine occupies only the N-terminus of the H1 molecules. It is suggested that this methionine is an uncleaved initiator methionine. The presence of these methionine-containing minor H1 subfractions varies in different tissues.     

Cryptococcus neoformans: A central nervous system isolate from an AIDS patient that is rhinotropic in a normal mouse model

A strain of Cryptococcus neoformans that was isolated from the cerebrospinal fluid of a human diagnosed as having acquired immunodeficiency syndrome (AIDS), and that produced cutaneous lesions in experimentally infected, normal mice is described. Although no unusual cutaneous manifestations were noted in the patient's records, this isolate of C. neoformans proved to be dermotropic when injected intravenously into CD-1 mice. The LD₅₀ at 28 days post infection ranged from 3.6–7.5×10⁵ cells per mouse, and in vitro growth rate studies demonstrated that this isolate grew well at 35 °C and at 37 °C, but did not grow at 40 °C and higher. This isolate was rhinotropic producing large granulomatous lesions in the nasal tissues. Other cutaneous tissues affected were the periocular tissues, ears, feet and tail, although the granulomas were nodular in structure and less necrotic than the nasal lesions. The brain, lungs, liver, kidneys and spleen also were culture positive for C. neoformans. Histopathologically, each affected tissue examined had large densities of yeast cells and a chronic, granulomatous host response. Animals surviving the infection appeared to develop a commensal-type relationship with the infective yeast. This is the first report of an isolate of C. neoformans from an AIDS patient that has caused cutaneous manifestations in an animal model. The model described in this report may be useful for elucidating pathogenic mechanisms of cryptococcosis, particularly cutaneous manifestations of the disease.     

Studies on detection of Candida antigen in the sera of mice inoculated orally with Candida albicans

Summary The authors succeeded in establishing a murine model of systemic candidiasis being disseminated from the primary gastrointestinal lesions caused by oral inoculation of Candida albicans. Using this model, an attempt was made for detecting the Candida antigen by enzyme-linked immunosorbent assay using avidin-biotin (AB-ELISA) from the serum of infected mice.Gastrointestinal candidiasis was formed in all of the 20 mice treated with the drugs (antibiotics, antineoplastic agents, hydrocortisone, etc.) and inoculated orally with C. albicans. Fourteen of these mice suffered from submucosal candidiasis, and C. albicans was cultured from the visceral organs in 12 of them. The assay by AB-ELISA was able to detect 1.0 ng/ml Candida mannan in the mouse serum. The Candida antigen was detected in the sera of 11 of the 14 mice with submucosal candidiasis. However, the antigen could not be detected in the sera of the 6 mice with intramucosal candidiasis.The assay by AB-ELISA is more sensitive and specific for the diagnosis of systemic candidiasis than other serological assays.     

Cyclopiazonic acid in combination with aflatoxins,zearalenone and ochratoxin A in Indonesian corn

The mycotoxin, cyclopiazonic acid (CPA), was detected at concentrations as high as 9 ppm in 21 of 26 corn samples from a Bogor poultry feedmill. This is the first demonstration of the natural occurrence of CPA in Indonesia. CPA was always accompanied by other mycotoxins, especially aflatoxins, suggesting that the interactive toxicity of these mycotoxins to poultry should be investigated.     

Developmental appearance of the Ca2+-binding proteins parvalbumin,calbindin D-28K,S-100 proteins and calmodulin during testicular development in the rat

Summary Calcium and intracellular Ca²⁺-binding proteins are possibly involved in hormone production and spermatogenesis in rat testis. Parvalbumin, calbindin D-28K, S-100 proteins and calmodulin were localized in the Leydig cells, which are sites of testosterone synthesis. Only the appearance of parvalbumin-immunoreactivity is closely correlated to testosterone production during development of the testes. Calbindin D-28K-immunoreactivity persisted in foetal-type Leydig cells and in adult-type Leydig cells at all stages of development. S-100-immunoreactivity was low during all foetal stages, absent between birth and puberty, and increased thereafter. Calmodulin staining is most prominent in the cytoplasm of developing spermatocytes and of maturing spermatids. All four proteins co-exist in the seminiferous tubules. The distinct localization and developmental appearance of these proteins suggests different regulatory roles in Leydig cell function and spermatogenesis.     

Maternal-embryonic relationships in the goodeid teleost,Xenoophorus captivus

In goodeid teleosts, prolonged embryonic development takes place within the ovarian cavity. Apposed maternal and embryonic epithelia interface via a nutritive liquid (embryotrophe) and facilitate aplacental matrotrophy. The role of the internal ovarian epithelium (IOE) in providing proteins for the embryotrophe has been studied using transmission electron-microscopic examinations of both the resting and the active ovarian lining, and isoelectric focusing of embryotrophe and maternal blood serum. The simple IOE is apparently composed of only one, filament-containing cell-type. In the non-gravid ovary these cells are cuboidal to columnar in shape, and are either compact and electron-dense or oedematous and light. During gestation, swelling of the ovarian connective tissue gives rise to dovetailing of the IOE with the subjacent capillary plexus. Part of the IOE overlying the capillaries becomes stretched, resulting in a thin endothelium-like demarcation. The nuclei and the bulk of the cytoplasm are usually recessed between the meshes of the protruding capillary network. The blood-embryotrophe pathway is thus reduced in places, to less than one m. The active form of the IOE contains a well-developed vacuolar apparatus composed of small vesicles, vacuoles, multivesicular bodies, and a few lysosomes. Elements of the RER are sparsely distributed throughout the cytoplasm. Endocytotic activity is observable at the apical and basolateral plasma membrane. Isoelectric focusing of both serum and embryotrophe produces numerous bands each between pI 4–8, which reveal many homologies. The intensity of corresponding bands varies considerably. It is concluded that the cells of the IOE provide a transport pathway for serum-derived macromolecular substances rather than produce proteinaceous secretions.     

Immunocytochemical studies on the pituitary pars distalis of the Japanese long-fingered bat,Miniopterus schreibersii fuliginosus

Summary Immunocytochemical studies were performed to describe the characteristics of cell types and their distribution in the pars distalis of Japanese long-fingered bat, Miniopterus schreibersii fuliginosus, collected at various stages of the reproductive cycle. Six distinct cell types have been identified in the pars distalis by the unlabeled immunoperoxidase technique and by the ABC method. Growth hormone (GH) and prolactin (PRL) cells were immunostained with antisera against chicken GH and ovine PRL. The GH-immunoreactive cells were round or oval orangeophilic cells distributed throughout the pars distalis with prominent aggregation in the posterolateral region. The PRL cells were pleomorphic carminophilic cells that occurred in small groups within the central and dorsocaudal regions of the pars distalis. They were sparsely distributed in the central region of the pars distalis in the hibernating bats, but increased significantly in the pregnant and lactating bats. The adrenocorticotropic (ACTH) cells were large round or polygonal amphophilic cells in the rostroventral and ventrolateral regions of the pars distalis. The thyrotropic (TSH) cells were small rounded or polygonal and distributed mainly in the ventrolateral region of the pars distalis. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) cells were identified immunocytochemically with antisera against the specific beta subunits of ovine LH and rat FSH. There were two populations of LH and FSH cells, one aggregated in the zona tuberalis and the other scattered singly throughout the rest of the pars distalis. The aggregated cells were immunoreactive with both antisera directed to LH and FSH, while scattered cells were reactive solely with antiserum to either LH or FSH and exhibited seasonal variations. In females, the proportional volume of the pars distalis occupied by LH cells was significantly reduced during pregnancy and lactation. No evidence of involution was observed in pars distalis cells except for PRL cells in males or females during hibernation.