Role of endopeptidase in motility induction in apyrene silkworm spermatozoa; micropore formation in the flagellar membrane

Summary Immotile apyrene spermatozoa of the silkworm have a thick electron-dense flagellar membrane. On activation of apyrene spermatozoa by initiatorin, a prostatic endopeptidase of the silkworm, or by trypsin, the flagellar membrane becomes thinner, with the formation of many micropores. It then resembles that of motile apyrene spermatozoa in vivo.     

Physiological role of apyrene spermatozoa ofBombyx mori

Summary Observation by electron and phase-contrast microscopy demonstrated that inBombyx mori the dissociation of eupyrene bundles, apparently through digestion of the prostatic secretion or an endopeptidase, was promoted by the vigorously flagellating movement of apyrene spermatozoa in the spermatophore.     

Prolongation of the duration of motility and fertilizing ability of rainbow trout spermatozoa by the addition of theophylline to the dilution medium

After rainbow Trout sperm were diluted in 0.01 and 0.001 M theophylline media, motility and fertilizing ability were prolonged as compared to the control media without theophylline. However, the motility observed was lower and of a different type than normal motility. This suggests that other factors besides cyclic nucleotides intervene in the motility of Trout spermatozoa.     

Scanning and transmission electron microscopic evidence of epithelial phagocytosis of spermatozoa in the terminal region of the vas deferens of the cat

Summary Scanning and transmission electron microscopic observations have been made in the terminal region of the vas deferens of the cat, with emphasis on the occurrence of spermiophagy. The present study has revealed that epithelial cells as well as luminal macrophages are extensively and actively involved in phagocytosis of spermatozoa. The mechanism of the spermiophagy is discussed, in relation to a possible role of the epithelial cells, as one function of the vas deferens.     

Induction of apoptosis and CD10/neutral endopeptidase expression by jaspamide in HL-60 line cells

Jaspamide (jasplakinolide) is a natural peptide isolated from marine sponges of Jaspis species and has fungicidal and growth-inhibiting activities. We characterized the jasplakinolide-induced loss of viability by programmed cell death in the HL-60 human promyelocytic leukemia cell line and found that this process was accompanied by neutral endopeptidase (NEP)/CD10 expression on the surface of the apoptotic cells. HL-60 cells do not normally express detectable amounts of NEP/CD10 on their surface or intracytoplasmically, but upon jaspamide treatment, CD10 was synthesized de novo, its expression being inhibited by cycloheximide pretreatment. Once synthesized, NEP/CD10 interfered with the jasplakinolide signal delivered to HL-60 cells. Inhibition of NEP/CD10 by the NEP inhibitor phosphoramidon or by an anti-CD10 monoclonal antibody significantly increased apoptosis induction. The appearance of CD10 on the cell surface was blocked by preincubation of the cells with the monocytic/macrophage-differentiating agents vitamin D3 and phorbol 12-myristate 13-acetate, but not by the granulocytic differentiating agents retinoic acid or dimethyl sulfoxide. Moreover, in the promonocytic U937 and mature monocytic THP-1 cell lines, jaspamide induced apoptosis but not CD10 expression. In HL-60 cells, CD10 expression was partially but not totally blocked by the broad-spectrum caspase inhibitor benzyloxacarbonyl-Val-Ala-Asp-fluoromethylketone, indicating a connection between apoptosis induction and CD10 synthesis. Our findings suggest that the CD10 expression is related to the programmed cell death induction by jaspamide, and also with the process of granulocytic differentiation in HL-60 cells. Received 22 April 2002; received after revision 8 June 2002; accepted 10 June 2002     

Duration of hornet sleep induced by ether anesthesia is curtailed by exposure to sun or UV irradiation

Irradiation of hornets anesthetized by diethyl ether curtails their sleep duration from the ordinary 20–30 min to a mere 2–3 min. This effect on sleep is dependent on the intensity of the sun irradiation or, when exposed to monochromatic UV at 366 nm, on the duration of the irradiation. Of the various hornet cuticular areas of the body, the yellow cuticular areas of the abdominal segments are the most sensitive to the treatment. We assume that the cuticles of both live and dead hornets act as a converter of light to electric energy.     

The mode of antifungal action of plant, insect and human defensins

Defensins are small (~5 kDa), basic, cysteine-rich antimicrobial peptides that fulfill an important role in the innate immunity of their host by combating pathogenic invading micro-organisms. Defensins can inhibit the growth or virulence of microorganisms directly or can do so indirectly by enhancing the host's immune system. Because of their wide distribution in nature, defensins are believed to be ancient molecules with a common ancestor that arose more than a billion years ago. This review summarizes current knowledge concerning the mode of antifungal action of plant, insect and human defensins.     

A pivotal role for serotonin (5HT) in the regulation of beta adrenoceptors by antidepressants: reversibility of the action of parachlorophenylalanine by 5-hydroxytroptophan

Summary An acute reduction in the synaptic availability of serotonin (5HT) by p-chlorophenlalanine (PCPA) nullifies the decrease in the density of cortical beta adrenoceptors caused by desipramine (DMI) but does not appreciably alter the attenuation of the norepinephrine (NE) sensitive adenylate cyclase. The analysis of competition-binding curves of [³H]-dihydroalprenolol shows that the affinity of the agonist (–)-isoproterenol for cortical beta adrenoceptors is profoundly reduced following PCPA. This reduction in agonist affinity is enhanced by DMI. Resupplying 5HT by by-passing trptophan hydroxylase inhibition, by administering 5-hydroxytryptophan, converts a DMI non-responsive to a DMI responsive beta adrenoceptor population and shifts the markedly decreased agonist affinity towards the affinity values found in control preparations. The results demonstrate the pivotal role of 5HT in the regulation of the density and agonist affinity characteristics of cortical beta adrenoceptors and contribute to the scientific basis of the serotonin-norepinephrine link hypothesis of affective disorders.Acknowledgments. This work was supported by USPHS grant MH-29228 and the Tennessee Department of Mental Health and Mental Retardation. Present address of L. R. Sterank: NOVA Pharmaceutical Corporation, Baltimore (MD 21228, USA).     

Control of respiration by nitric oxide in Keilin-Hartree particles,mitochondria and SH-SY5Y neuroblastoma cells

The pattern of cytochrome c oxidase inhibition by nitric oxide (NO) was investigated polarographically using Keilin-Hartree particles, mitochondria and human neuroblastoma cells. NO reacts with purified cytochrome c oxidase forming either a nitrosyl- or a nitrite-inhibited derivative, displaying distinct kinetics and light sensitivity of respiration recovery in the absence of free NO. Keilin-Hartree particles or cells, respiring either on endogenous substrates alone or in the presence of ascorbate, as well as state 3and state 4mitochondria respiring on glutamate and malate, displayed the rapid recovery characteristic of the nitrite derivative. All systems, when respiring in the presence of tetramethyl-p-phenylenediamine, were characterised by the slower, light-sensitive recovery typical of the nitrosyl derivative. Together the results suggest that the reaction of NO with cytochrome c oxidase in situ follows two alternative inhibition pathways, depending on the electron flux through the respiratory chain.Received 1 April 2003; received after revision 22 May 2003; accepted 3 June 2003     

Evolutionary implications of pyrrolizidine alkaloid assimilation by danaine and ithomiine larvae (Lepidoptera: Nymphalidae)

Summary Larvae of danaine and ithomiine butterflies assimilate pyrrolizidine alkaloids painted on their larval host plants. This finding supports the theory of the common ancestral use of these compounds by Ithomiinae and Danainae.     

Nonlinear combination parametric resonance of axially accelerating viscoelastic strings constituted by the standard linear solid model

Nonlinear combination parametric resonance is investigated for an axially accelerating viscoelastic string. The governing equation of in-planar motion of the string is established by introducing a coordinate transform in the Eulerian equation of a string with moving boundaries. The string under investigation is constituted by the standard linear solid model in which the material, not partial, time derivative was used. The governing equation leads to the Mote model for transverse vibration by omitting the lo...     

Mechanical and biochemical characterization of the contraction elicited by a calcium-independent myosin light chain kinase in chemically skinned smooth muscle

Summary The contraction induced by a Ca²⁺-independent myosin light chain kinase (MLCK-) was characterized in terms of isometric force (F_o), immediate elastic recoil (SE), unloaded shortening velocity (V_us), shortening under a constant load and ATPase activity of chemically skinned smooth muscle preparations. These parameters were compared to those measured in a Ca²⁺-induced contraction to assess the nature of cross bridge interaction in the MLCK-induced contraction. F_o developed in chicken gizzard fibers as well as SE were similar in contractions elicited by either agent. V_us in the contraction induced by MLCK-(0.36 mg/ml) was similar though averaged 39.3±8.9% less than V_us induced by Ca²⁺ (1.6x10^–6M) in the control fibers. Addition of Ca²⁺ (1.6x10^–6M) to a contraction induced by MLCK-resulted in small increases in both F_o and V_us. Shortening under a constant load was similar for both types of contractions. The contraction induced by MLCK-was accompanied by an increased rate of ATP hydrolysis. The MLCK-induced contraction is thus kinetically similar though not identical to a contraction induced by Ca²⁺. We conclude that with respect to actin-myosin interaction, MLCK- and Ca²⁺-induced contractions are similar.     

Enhancement of vertebrate cardiogenesis by a lectin from perivitelline fluid of horseshoe crab embryo

Cardiac myocytes are the first cells to differentiate during the development of a vertebrate embryo. A wide variety of molecules take part in various steps in this process. While exploring biologically active molecules from marine sources, we found that a constituent of perivitelline fluid from embryos of the Indian horseshoe crab can enhance growth and differentiation of chick embryonic heart. We have purified the factor and identified the cardiac promoting molecule to be a novel lectin. We show that this molecule influences cardiac development by increasing the number of cells constituting the heart and by modulating the expression of several cardiac development regulatory genes in chick embryos. Using mouse embryonic stem cells we show that the cardiac myocyte-enhancing capacity of this molecule extends to mammals and its effects can be blocked using methylated sugars. This molecule may prove to be an important tool in the study of cardiomyocyte differentiation.     

Modeling and Forecasting the Yield Curve by an Extended Nelson‐Siegel Class of Models: A Quantile Autoregression Approach

This paper compares the in‐sample fitting and the out‐of‐sample forecasting performances of four distinct Nelson–Siegel class models: Nelson–Siegel, Bliss, Svensson, and a five‐factor model we propose in order to enhance the fitting flexibility. The introduction of the fifth factor resulted in superior adjustment to the data. For the forecasting exercise the paper contrasts the performances of the term structure models in association with the following econometric methods: quantile autoregression evaluated at the median, VAR, AR, and a random walk. As a pattern, the quantile procedure delivered the best results for longer forecasting horizons. Copyright © 2011 John Wiley & Sons, Ltd.