Structural studies on equine chorionic gonadotropin

The amino acid sequence of the subunit of equine chorionic gonadotropin (eCG, also pregnant mare serum gonadotropin, PMSG) has been determined. Overlapping peptides from tryptic and chymotrypic digests were isolated by a two-dimensional peptide mapping technique and sequenced by the Edman procedure. The proposed amino acid sequence of eCG is: (**Denotes carbohydrate attachment points.) This sequence differs significantly from that proposed by Rathnamet al. (1978) for equine follitropin subunit; in particular, their sequence lacked the first fourteen residues.For the subunit we have placed in sequence 104 amino acid residues by direct sequence determination and peptide overlap procedures; in addition, 37 residues have been placed provisionally by homology with the human chorionic gonadotropin (hCG) sequence and composition and/or sequence data for the peptides isolated in the present studies. Difficulties in the procurement of the hormone have stalled completion of the -subunit amino acid sequence determination. The data now available indicate that eCG -subunit is highly homologous to hCG subunit and the subunits of luteinizing hormone from the pituitary gland of the several species so far described. The proposed partial sequence of eCG is:     

Cellular localization of thiol-proteinase inhibitor in the epidermis of the newborn rat

Summary In cichlid, poecilid and centrarchid fishes luteinizing hormone releasing hormone (LHRH)-immunoreactive neurons are found in a cell group (nucleus olfactoretinalis) located at the transition between the ventral telencephalon and olfactory bulb. Processes of these neurons project to the contralateral retina, traveling along the border between the internal plexiform and internal nuclear layer, and probably terminating on amacrine or bipolar cells. Horseradish peroxidase (HRP) injected into the eye or optic nerve is transported retrogradely in the optic nerve to the contralateral nucleus olfactoretinalis where neuronal perikarya are labeled. Labeled processes leave this nucleus in a rostral direction and terminate in the olfactory bulb. The nucleus olfactoretinalis is present only in fishes, such as cichlids, poecilids and centrarchids, in which the olfactory bulbs border directly the telencephalic hemispheres. In cyprinid, silurid and notopterid fishes, in which the olfactory bulbs lie beneath the olfactory epithelium and are connected to the telencephalon via olfactory stalks, the nucleus olfactoretinalis or a comparable arrangement of LHRH-immunoreactive neurons is lacking. After retrograde transport of HRP in the optic nerve of these fishes no labeling of neurons in the telencephalon occurred. It is proposed that the nucleus olfactoretinalis anatomically and functionally interconnects and integrates parts of the olfactory and optic systems.     

Phagocytosis of erythrocytes by the proximal tubule of the rat kidney

Summary Morphological examination of kidney biopsies from patients with glomerulonephritis and hematuria has revealed the presence of erythrocytes within epithelial cells of the proximal tubule. This observation suggested that the proximal tubule might be capable of phagocytizing morphologically intact erythrocytes. To examine this possibility small quantities of heparinized autologous blood were injected into surface convolutions of proximal tubules of the rat kidney using standard micropuncture techniques. At time intervals ranging from 10 min to 120 h after injection, the kidneys were preserved for light and transmission electron microscopy by drip-fixation with a half-strength Karnovsky's glutaraldehyde-formaldehyde fixative.During the initial 6 h there was a flattening of the brush border and accumulation of electron-dense material representing hemoglobin in apical vacuoles and in lysosome-like structures. From 6 to 15 h after micropuncture, there was progressive loss of the brush border and the simultaneous formation of pseudopodia-like evaginations that extended from the apical plasma membrane and surrounded the individual erythrocytes. By 18 and 24 h, erythrocytes were observed in the proximal tubule cells. At later time intervals, edema, lymphocytic infiltration, and fibrosis were observed in the interstitium. In addition, crystalline structures were present in the lumen and the cells of both proximal and distal tubules. These findings suggest that in addition to their well-established ability to pinocytize hemoglobin and other proteins, the cells of the proximal tubule are capable of phagocytizing morphologically intact autologous erythrocytes. It is possible that phagocytosis by the proximal tubule cells may play a role in the disposal of erythrocytes from the tubular fluid in hematuric conditions.     

Occurrence,localization, and possible significance of an ornithine-containing lipid in Paracoccus denitrificans

A ninhydrin-positive, phosphorus-negative lipid from Paracoccus denitrificans ATCC 13543 has been isolated and purified by mild alkaline methanolysis followed by silicic acid column chromatography and preparative thin-layer chromatography. The lipid was identified as an ornithine-containing lipid. The major ester-linked fatty acid was cis vaccenic acid. Major amide-linked fatty acids were 3-OH-20:1 and 3-OH-18:0. Ornithine-containing lipid was a major lipid component of P. denitrificans. Phospholipids made up about 57% and ornithine-containing lipid about 14% of the weight of the total lipid of the organism. The ratios of lipid ornithine: lipid phosphorus were 0.23, 0.65 and 0.58 in cytoplasmic membrane, outer membrane, and an NaCl extract, which is thought to represent chiefly outer membrane, respectively. Thus ornithine-containing lipid appears to be present in larger amounts in outer membrane than cytoplasmic membrane. No substantial variations in lipid ornithine levels were noted in stationary phase versus exposnential phase organisms, organisms grown in complex medium versus organisms grown in minimal medium with and without amino acid supplements, or in organisms grown in low phosphate-containing medium.Non standard abbreviations TLC thin-layer chromatography - Tris-HCl tris(hydroxymethyl)aminomethane hydrochloride - TMS trimethylsilyl - TFA triluoroacetyl - NPPN ninhydrin-positive, phosphorus-negative - ECL equivalent chain length     

Plasmids of serogroup 1 strains ofLegionella pneumophila

Twelve strains ofLegionella pneumophila were tested for the presence of plasmid DNA. Three strains, belonging to serogroup 1, had large plasmids of 83.8×10⁶ daltons, as determined by electron microscopy. A fourth strain, also from serogroup 1, had a similar large plasmid in addition to a smaller plasmid. Restriction analysis of plasmid DNA isolated from the strains with a single size plasmid indicated that the plasmids were structurally very similar. The biologic functions of these plasmids are yet to be determined.     

The Sabinas syndrome

We have defined a new autosomal recessive disorder in patients stemming from a small community in northern Mexico. Diagnosable at birth, its major symptoms include brittle hair, mental retardation, and nail dysplasia. Structural hair abnormalities are seen by both light and electron microscopy. Hair cystine content is reduced while the copper/zinc ratio in hair is increased.     

The relationship between split-line orientation and in vivo bone strain in galago (G. crassicaudatus) and macaque (Macaca mulatta and M. fascicularis) Mandibles

There is still disagreement concerning the functional significance of split-line patterns in bone. This study was undertaken to reexamine the mechanical forces hypothesis for split-line formation by comparing split-line patterns with in vivo mandibular bone strain patterns. The relationship between split-line orientation and in vivo stress and strain patterns on macaque and galago mandibles was examined during jaw opening and the power stroke of mastication and incision. An attempt was made to relate split-line orientation to the direction of tensile stress and strain along the primate mandible. In addition, we also investigated the alternative possibility that split-line orientation is related to the direction of low stresses (and strains) on the primate mandible. The results of this study showed that there was no consistent relationship between split-line orientation and the principal strains or stresses. Thus, split-lines did not run consistently in the direction of high or low stress and strain. Therefore, we have concluded that split-line orientation provides little useful information for inferring patterns of stress and strain in bone.     

Surface Changes in Mild Steel Coupons from the Action of Corrosion-Causing Bacteria

Changes which occur on the surface of mild steel coupons submerged in cultures of an Fe(III)-reducing bacterium, isolated from corroded pipe systems carrying crude oil, were studied microscopically to investigate the interaction between the corrosion-causing bacterium and the corroding mild steel coupon. Under micro-aerobic conditions and in the absence of the bacteria, a dense, crystalline, amorphous coat formed on the surface of the steel coupons. In the presence of bacteria the surface coat was extensively removed, exposing the bare metal to the environment. After about 2 weeks of exposure, the removal of the surface coating was followed by colonization of the metal surface by the bacteria. Colonization was mediated by fibrous, exopolysaccharidic material formed by the bacteria. Extension of studies to other bacteria isolated from crude oil and corroded pipes reveals that the formation of exopolysaccharide fibers and possession of adherent properties are common characteristics of bacteria from crude oil systems.     

Oxidation of Ethylene Glycol by a Salt-Requiring Bacterium

Bacterium T-52, cultured on ethylene glycol, readily oxidized glycolate and glyoxylate and exhibited elevated activities of ethylene glycol dehydrogenase and glycolate oxidase. Labeled glyoxylate was identified in reaction mixtures containing [¹⁴C]-ethylene glycol, but no glycolate was detected. The most likely pathway of ethylene glycol catabolism by bacterium T-52 is sequential oxidation to glycolate and glyoxylate.     

Ixodes dammini: Induced skin lesions in guinea pigs and rabbits compared to erythema chronicum migrans in patients with lyme arthritis

Erythematous skin lesions occurred in rabbits 2 days after being fed upon by larvae or nymphs of the tick, Ixodes dammini. Similar lesions occurred in guinea pigs 7 days after a primary infestation with either larvae or nymphs. Host resistance to secondary feeding by larvae was demonstrated in guinea pigs and rabbits. Host resistance to secondary feeding by nymphs was seen in guinea pigs, but not in rabbits. Guinea pigs developed resistance to nymphs after being previously fed upon twice by larvae. All skin lesions in resistant guinea pigs contained large accumulations of basophils (49–76% of cells) with smaller (20–33%), but significant, numbers of eosinophils. These responses were characteristic of strong cutaneous basophil hypersensitivity reactions. Primary and secondary lesions in rabbits fed upon by larvae contained mostly mononuclear cells (46–52%) and moderate numbers (16–30%) of basophils and eosinophils. Primary and secondary lesions in rabbits fed upon by nymphs had few (3–11%) basophils and eosinophils and were dominated by mononuclear cells (73–86%). Thus, acquired resistance in guinea pigs and rabbits was associated with cutaneous basophil and eosinophil responses and the lack of resistance of rabbits to nymphs was associated with erythematous lesions dominated by mononuclear cells. The mononuclear nature of rabbit lesions induced by nymphal feeding was similar to that seen in erythema chronicum migrans in Lyme arthritis patients who are thought to have been fed upon by I. dammini nymphs. This study confirms the cutaneous basophil hypersensitivity characteristics of lesions in guinea pigs resistant to ticks and demonstrates a relationship between the mononuclear cell response of rabbits to nymphal I. dammini and the cellular response seen in patients with erythema chronicum migrans and Lyme arthritis.