Sperm motility in the presence of boundaries

The fluid dynamics of sperm motility near both rigid and elastic walls is studied using the immersed boundary method. Simulations of both single and interacting organisms are presented. In particular, we find that nearby organisms originally undulating with a 90° phase shift may adjust their relative swimming velocities and phase-lock. Comparisons with previous analytical results are also discussed. The tendency of a near-wall to attract organisms is demonstrated.     

Regulation of insulin-like growth factor (IGF) binding protein-2 synthesis and degradation by platelet-derived growth factor and the IGFs is enhanced by serum deprivation in vascular smooth muscle cells

Growth factors such as platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF-1) stimulate proliferation and migration of vascular smooth muscle cells (SMC). IGF-l bioactivity is modulated by high-affinity binding proteins (IGFBP) which are important regulators of these processes. Procine vascular SMC synthesize IGFBP-2 and IGFBP-4 in vitro. In the present study, levels of IGFBP-2 in conditioned media (CM) were increased approximately 1.6 to 2.2-fold when cells were exposed to PDGF (20 ng.ml) or insulin (5 μg/ml) for 24 hr following a 24 hr incubation in serum-free media, or following a 72 hr exposure to either growth factor. Similar increases in IGFBP-2 mRNA levels were observed. Exposure of cells to PDGF for 24 hr without prior serum deprivation resulted in smaller (47 ± 11%) increases in IGFBP-2 protein levels but failed to alter mRNA levels. IGF-1, FGF-b? and EGF failed to increase IGFBP-2 using either experimental paradigm. In contrast, IGFBP-2 protein levels were consistently decreased (75 ± 14%) after 72 hr of exposure to IGF-II without corresponding decreases in IGFBP-2 mRNA levels. Immunoprecipitation of [³⁵S] methionine-labeled IGFBP-2 indicated that this decrease was not due to a decrease in synthesis of IGFBP-2. Immunoblot analysis of CM from cells treated with IGF-II indicated that the decrease in intact protein corresponded with an increase in two non-IGF binding IGFBP-2 fragments of 22 and 14 kD. Increased abundance of these fragements was also observed following IGF-I exposure, although corresponding decreases in intact IGFBP-2 were not usually observed. The relative abundance of these fragments did not appear to be affected by treatment with PDGF or insulin. In contrast to IGFBP-2, regulation of the levels of IGFBP-4 in CM did not appear to be altered by serum deprivation. Insulin consistently increased IGFBP-4 mRNA and protein levels under all situations. PDGF tended to increase IGFBP-4 protein levels, although this effect was less consistent and not as great as the increase observe with insulin. Treatment with IGF-I or -ll consistently decreased IGFBP-4 levels in CM but tended to increase their mRNA levels under all situations. These data indicate that insulin, PDGF, and the IGFs regulate both IGFBP-2 and IGFBP-4. While PDGF and insulin stimulate IGFBP-2 and 4 synthesis, the IGFs appear to activate protease(s) which regulate IGFBP-2 and -4 levels post-translationally. The regulation of IGFBP-2 levels by each of these mechanisms appears to be amplified by serum deprivation, but this is not observed with IGFBP-4. © 1995 Wiley-Liss, Inc.     

Two New Species of Aphelenchoididae (Nemata) from Declining Red Pines in Maryland

Aphelenchoides resinosi n. sp. and Ektaphelenchus joyceae n. sp. are described and illustrated from red pines of the Allegheny plateau of Maryland, USA. The new species were found in trees infested with Bursaphelenchus xylophilus. Primary diagnostic characters of A. resinosi females are constriction of the head, basal stylet knobs, tong postuterine sac, two incisures in the lateral field, and conical tail four to five anal body widths long with a simple terminal mucro. Diagnostic characters of the males are two pairs of subventral caudal papillae and spicule shape: Primary diagnostic characters of E. joyceae females are a slight constriction of the head, six similar lips, conical tail, and short postuterine sac. Diagnostic characters of the males are spicule size and shape, a single row of spermatocytes, and one pair of caudal papillae. Within-tree distributions of A. resinosi and E. joyceae are presented. A total of 70% of both red-needled and chlorotic-needled trees in the study were positive for A. resinosi and E. joyceae. Branch hierarchy was related to the percentage of samples positive for A. resinosi.     

Structural characterization of glycosphingolipids from the eggs of Schistosoma mansoni and Schistosoma japonicum

The granulomatous pathology in human intestinal schistosomiasisis induced primarily by the egg antigens of schistosome, a parasitictrematode. Glycolipids and glycoproteins were extracted fromthe eggs of the two major species which infect human, Schistosomamansoni and Schistosoma japonicum, for structural characterizationbased on highly sensitive mass spectrometric analysis coupledwith chemical derivatization. Here, we demonstrate that a seriesof uniquely multifucosylated glycosphingolipids constitute themajor egg glycolipids of S.mansoni but not of S.japonicum. TheS.mansoni glycosphingolipids were found to be extended by varyingnumbers of an unusual repeating unit,     

Meningococcal pilin: a glycoprotein substituted with digalactosyl 2,4-diacetamido-2,4,6-trideoxyhexose

Neisseria meningitidis pili are filamentous protein structures that are essential adhesins in capsulate bacteria. Pili of adhesion variants of meningococcal strain C311 contain glycosyl residues on pilin (PilE), their major structural subunit. Despite the presence of three potential N -linked glycosylation sites, none appears to be occupied in these pilins. Instead, a novel O -linked trisaccharide substituent, not previously found as a constituent of glycoproteins, is present within a peptide spanning amino acid residues 45 to 73 of the PilE molecule. This structure contains a terminal 1-4-linked digalactose moiety covalently linked to a 2,4-diacetamido-2,4,6-trideoxyhexose sugar which is directly attached to pilin. Pilins derived from galactose epimerase ( galE ) mutants lack the digalactosyl moiety, but retain the diacetamidotrideoxyhexose substitution. Both parental (#3) pilins and those derived from a hyper-adherent variant (#16) contained identical sugar substitutions in this region of pilin, and galE mutants of #3 were similar to the parental phenotype in their adherence to host cells. These studies have confirmed our previous observations that meningococcal pili are glycosylated and provided the first structural evidence for the presence of covalently linked carbohydrate on pili. In addition, they have revealed a completely novel protein/saccharide linkage.     

The enzymic defect and storage products in canine fucosidosis.

A marked deficiency of alpha-L-fucosidase and the accumulation of fucose-containing glycoasparagines were found in the brains of two English Springer spaniels suffering from a progressive nervous disorder. Both forms of alpha-L-fucosidase in normal brain, which are separable by ion-exchange chromatography, are absent from the affected animals. The storage products were characterized by t.l.c., gel filtration, g.l.c. and fast-atom-bombardment mass spectrometry. The postulated structures of the main components are: (formula; see text) The enzymic defect and nature of storage products justify designation of this disorder as canine fucosidosis.     

Deoxyribonucleic acid synthesis and deoxyribonucleic acid-polymerase activity during early germination of wheat embryos at high and low viability

³H-thymidine incorporation and DNA-polymerase activity during early hours of wheat embryo germination at two viability levels have been studied. The patterns of two biosynthetic activities, as well as the dependence of DNA synthesis on protein synthesis, indicated the presence of a delay in the early phase of imbibition of the aged embryos with respect to viable germs.     

Fast Atom Bombardment-High Field Magnet Mass Spectrometry of 6000 Dalton polypeptides

Using a combination of Fast Atom Bombardment lonisation and High Field Magnet — Mass Spectrometry we demonstrate here the ability to observe, for the first time, the accurate molecular weights of polypeptides or other important bioorganic substances up to 6000 Dalton in size. This claim is substantiated with data on intact unreduced Insulin and on the intact sweet protein Monellin, which consists of three polypeptide chains.     

Endocytosis of lysosomal alpha-galactosidase A by cultured fibroblasts from patients with Fabry disease.

The endocytosis of alpha-galactosidase A was studied in cultured fibroblasts from patients with Fabry disease. Alpha-galactosidase A was purified from human placenta by chromatography on concanavalin A-Sepharose, DEAE-cellulose, and N-epsilon-aminocaproyl-alpha-D-galactosylamine-Sepharose. Separation of the high-uptake form of the enzyme from the low-uptake form was accomplished by chromatography on ECTEOLA-cellulose. With the high-uptake form of the enzyme, the uptake was linear at low concentrations of enzyme and had a Kuptake of 0.01 U/ml of medium that corresponds to a Km of 5.0 x 10(-9) M. At high concentrations of enzyme, it became saturated. The high-uptake form could be converted to the low-uptake form by treatment with acid phosphatase. Mannose-6-P strongly inhibited the active uptake of the enzyme. Once taken up into the lysosomes of Fabry disease fibroblasts, alpha-galactosidase A activity was rapidly lost in the first 2 days of incubation at 37 degrees C, but was fairly stable for the next 6 days. The half-life of internalized alpha-galactosidase A activity was calculated to be 4 days. Crosslinking of the enzyme with hexamethylene diisocyanate did not increase the intracellular stability of alpha-galactosidase A activity.