Fine structure of the giant aflagellate spermatozoon in pseudostomum quadrioculatum (leuckart) (platyhelminthes,prolecithophora)

The giant aflagellate spermatozoa of P. quadrioculatum are composed of two different parts: a thicker head piece and a more slender tail piece. In the head there exist a large elongated nucleus and an elongated mitochondrial derivative situated in a groove-like cavity of the nucleus. In mature spermatozoa the nuclear material is arranged in many small membrane bounded areas. Both structures, nucleus and mitochondrial derivative, are spirally coiled. The outer part of the membrane in the mitochondrial derivative forms many loop-like foldings. Both organelles continue to the tail in form of two small, helically coiled ribbons; the nucleus is anchored within the mitochondrial derivative by an electron-opaque process. A sheath of spirally-orientated cortical microtubules starting from the tip of the head runs to the tip of the tail under the cell membrane. In addition, a second sheath of tubules occurs in the tail region, these tubules also run parallel to each other, but in the opposite direction to the microtubules of the outer sheath.The possible relations between the structures observed and the motility of the spermatozoa are discussed; in addition, some phylogenetic comments are attempted.Abbreviations c — cerebrum - com — cortical microtubules - cop — copulatory organ - fm — foldings of the mitochondrial membrane - l — lattice - mid — mitochondrial derivative - mt — microtubules - n — nucleus - ne — nuclear envelope - ph — pharynx - pn — protonephidium - rp — ribbon-like nuclear process - te — testis - tt — testis - tt — tip of the tail - vi — vitellarium - vs — vesicula seminalis     

Autophagic elimination of ribosomes during spermiogenesis provides energy for flagellar motility

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Influence of osmolality and ions on the activation and characteristics of zebrafish sperm motility

Despite the prevalence of zebrafish as a model scientific organism, understanding sperm function in this species is essentially limited to observations that osmotic shock initiates motility. During natural spawning, sperm encounter a range of environmental salinities as well as freshwater mixed with egg-associated ovarian fluid (OF), thus sperm are likely to be exposed to saline prior to egg contact. Effects of saline on sperm function in this model species are unknown, but likely to be important. Using computer assisted sperm analysis, this study addressed the effects of osmolality of spawning media and ionic composition and pH on the proportion of sperm becoming motile at activation (motility), as well as sperm velocity and path. When activated with tap water, motility was maximal (80%) at 10 s (earliest time measured), declining to 5% by 87 s postactivation. With activation at moderate osmolalities (∼160-200 mmol/kg) initial motility was decreased relative to low osmolality, increased from 10 to 30 s, and subsequently declined less rapidly (motility in 80 mM NaCl was 35%, 80%, and 60% at 10, 30 and 147 s, respectively). Thus, moderate osmolality increased duration, but introduced a temporal lag in motility onset. With moderate osmolalities, the rate of velocity decay was less than that with tap water activation. Sodium chloride and sucrose similarly impacted both motility and velocity. Replacement of NaCl with KCl, pH values ranging from 6.8 to 8.4, or the presence of gadolinium were without effect. Motility, but not velocity, was slightly supressed by Ca²⁺. Therefore, whereas pH and concentrations of Ca²⁺ or K⁺ of OF are unlikely to impact fertility via sperm motility, the OF contribution to spawning media osmolality may have pronounced effects on motility and velocity of sperm, factors previously correlated with fertility in other species.     

De novo identification of mammalian ciliary motility proteins using cryo-EM

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Induction of motility of apyrene spermatozoa and dissociation of Eupyrene sperm bundles of the silkmoth,Bombyx mori,by initiatorin and trypsin

Summary

The activator, or inducer of motility, of apyrene spermatozoa of the silkmoth, Bombyx mori, was shown to be present in the posterior glandula (g.) prostatica. The activity of this factor in this gland was lost by boiling at 100°C for 10 min. Bundles of eupyrene sperm were dissociated by treatment with either a g. prostatica homogenate or trypsin, and their dissociation was concentration-dependent. On the contrary, for activation of apyrene sperm, the optimal trypsin concentration was 0.45–1.80 μg/ml and activation decreased at higher and lower trypsin concentrations. Microscopic observation showed that the dissociation rate of eupyrene sperm bundles by the g. prostatica homogenate corresponded to that by 0.45–9.0 μg/ml of trypsin. An autolysate of the g. prostatica and digests of seminal fluid with the g. prostatica homogenate or trypsin did not activate apyrene sperm. Of 11 endopeptidase inhibitors tested, antipain, leupeptin, TLCK, TPCK and PMSF strongly inhibited sperm activation by the g. prostatica homogenate, suggesting that the activator is an endopeptidase of the wine protease type. The 6 exopeptidase inhibitors tested did not inhibit activation of apyrene spermatozoa and the dissociation of eupyrene sperm bundles are both caused by the same factor, initiatorin, an endopeptidase of the serine protease type present in the prostatic secretion.     

Nematicidal activity of powder and extracts of Melia azedarach fruits against Meloidogyne incognita

Pulverised lyophilised (dehydrated) Melia azedarach (Meliaceae) fruits (PMF) were tested in a dose–response pot experiment against juveniles (J2) of the root-knot nematode Meloidogyne incognita. Successively, with different extraction procedures, a polar (melia methanol extract, MME) and a non-polar (melia oil, MO) fragments were obtained and their effects were tested on nematode motility and development, in dose and time response bioassays and pot experiments. An EC₅₀ value was calculated for all experiments. A dose–response effect was found in pot bioassays using PMF and, after an incubation period of 24 and 48 h, the EC₅₀ values were calculated at 0.41% and 0.34% w/w, respectively. Motility bioassays revealed a dose and time dependent response effect, after exposure to MME, but not to MO. Doses of MME higher than 0.08% were nematicidal, whereas lower ones were nematostatic (the loss of motility as a result of the presence of the substance was reversible). In a pot experiment, MME doses higher than 2.5% w/w caused 100% nematode control with EC₅₀ value of 0.916% w/w.     

Attachment of Entamoeba histolytica to Glass in a Defined Maintenance Medium: Specific Requirement for Cysteine and Ascorbic Acid*

SYNOPSIS. Cysteine and ascorbic acid were previously shown to be required by Entamoeba histolytica trophozoites for attachment to glass, elongation, and ameboid movement as well as for short-term (12–24 h) survival in a balanced salt solution containing bovine serum albumin and a vitamin solution (Maintenance Medium 1). If the only function of cysteine and ascorbate was to decrease the redox potential, other reducing agents should be effective. However, the requirement for cysteine in the presence of ascorbic acid was highly specific. Equally effective were D- and L-cysteine; however, of many other compounds tested, only thioglycolic acid, ascorbic acid, or L-cystine (in decreasing order) were somewhat active. Under N₂ atmosphere, cysteine and ascorbic acid were still required, although their concentrations could be halved. The ability to attach in the maintenance medium was irreversibly lost after only 5 min of cysteine-ascorbic acid deprivation; however, there was no decrease in viability when the amebae were transferred to growth medium within 30 min. Cysteine thiol groups in the medium were oxidized rapidly regardless of the concentration of ascorbic acid or the presence of amebae; however, ascorbic acid prolonged attachment of amebae.     

The effect of dietary supplementation of nitric oxide donor and inhibitor on nNOS expression in and motility of the small intestine of broilers

Abstract

We investigated the effect of dietary supplementation of sodium nitroprusside (SNP), a nitric oxide (NO) donor, and N-nitro-L-arginine methyl ester (L-NAME), a NO inhibitor, on neuronal nitric oxide synthase (nNOS) expression in and motility of small intestinum in broilers. A total of 560, one-day-old Ross 308 hybrid mixed sex broiler chicks were divided randomly into one control and seven treatment groups for a 42 day feeding trial including starter phase (0–21 days) and grower phase (22–42 days). The control group was fed a basal diet and the experimental groups were the fed basal diet supplemented with 25, 50, 100 and 200 mg/kg SNP and 25, 50 or 100 mg/kg L-NAME. Ten chickens from each group were sacrificed to collect samples on days 21 and 42. The expression patterns of nNOS immunoreactivity in nerve fibers were determined by immunohistochemistry. In the contractility studies, longitudinal isolated strips of duodenum, jejunum and ileum were treated with 10^?5 M L-arginine and 10^?4 M SNP. Immunohistochemistry revealed that nNOS expression was not detectable in the duodenum or ileum of either the control or experimental groups. On the other hand, nNOS immunoreactivity in the jejunum control group showed a strong reaction on day 21, but the reaction was weak on day 42. nNOS expression clearly was suppressed on day 21 by the diet supplemented with L-NAME, while the diet supplemented with SNP stimulated nNOS expression on day 21. Contractility experiments revealed that spontaneous contractility of isolated strips of duodenum, jejunum and ileum showed no significant difference among groups. Spontaneous contractions of all strips were inhibited by L-arginine and SNP in all groups. The percentage inhibition rate of spontaneous contractions of jejunum application on days 21 and 42 after L-arginine decreased in the group supplemented with 100 mg/kg L-NAME. The percentage inhibition rate on day 21 after SNP application decreased in both groups that received 50 and 100 mg/kg L-NAME. We demonstrated the expression pattern of nNOS in nerve fibers in jejunum of broiler chickens. Contractility studies revealed that the NOS-NO pathway may play a role in smooth muscle contraction of small intestine of chickens. Feeding strategies that supplement NO donor and NO inhibitor can be of physiological importance to small intestine motility owing to alteration of nNOS expression in the jejunum.