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Elongated Spermatids (elongated + spermatid)

Distribution by Scientific Domains
Life Sciences100%

Selected Abstracts

The significance of feeding for reproduction in a male Metastriata tick, Haemaphysalis longicornis (Acari: Ixodidae)

ACTA ZOOLOGICA, Issue 1 2000
Tomohide Matsuo
In Haemaphysalis longicornis, secretions of the male accessory genital glands were regenerated by re-feeding for 3 or 4 days, although the secretions were almost completely released during the first copulation. It was also shown that spermatogenesis continued during re-feeding, since prospermia (elongated spermatids) were deposited in the seminal vesicle. A potent male seeks a receptive female on the host for copulation. The movement of males to different attachment sites occurred between the third and fourth day of re-feeding, and completely re-fed males (for 4 days) were able to copulate successfully. Spermatogenic cells, ranging from spermatogonia at the anterior end to prospermia at the posterior end, were found in fed males. Degeneration of spermatocytes at the great growth phase and developing spermatids prior to final development of prospermia were seen in virgin males without re-feeding after the first meal. Fully elongated spermatids (prospermia) appeared morphologically normal up to 10 days after the first feeding. Degeneration of spermatocytes and developing spermatids occurred from the second day and was almost complete by the fourth day. The degenerating cells shrank, became electron-dense, and finally died. A reduction in secretions of the four lobes of the accessory glands occurred during the 10 days after feeding. [source]

Differential expression of a Bombyx mori AHA1 homologue during spermatogenesis

INSECT MOLECULAR BIOLOGY, Issue 3 2005
Y. Miyagawa
Abstract The AHA1 (activator of Hsp90 ATPase) family of proteins were exclusively conserved from yeast to humans, but little is known about their tissue distribution or biological function. In this study, a cDNA for a Bombyx mori AHA1 homologue, BmAHA1, was isolated from the testes of larvae on day 3 of the fifth instar using an mRNA differential display method. This cDNA encodes a protein with 341 amino acid residues. Gene expression studies revealed that BmAHA1 mRNA occurred prominently in the testes. In situ hybridization and immunostaining showed that the BmAHA1 mRNA signals were strongly detected in spermatogonial cells and primary spermatocytes at the fifth larval instar stage, whereas the BmAha1 protein was abundant in round and elongated spermatids at the pupal stage. The localization pattern of the accumulated protein in the elongated spermatids was reminiscent of that reported previously for microtubules, but the BmAha1 protein showed a decrease in apparent concentration during maturation process. The stage- and cell-specific expression indicated that BmAha1 might play a role in silkworm spermatogenesis, especially in postmeiotic differentiation. [source]

Functional assessment of centrosomes of spermatozoa and spermatids microinjected into rabbit oocytes,

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 3 2009
Masahito Tachibana
Abstract Although intracytoplasmic sperm injection (ICSI) is a widely used assisted reproductive technique, the fertilization rates and pregnancy rates of immature spermatids especially in round spermatid injection (ROSI) remain very low. During mammalian fertilization, the sperm typically introduces its own centrosome which then acts as a microtubule organizing center (MTOC) and is essential for the male and female genome union. In order to evaluate the function of immature germ cell centrosomes, we used the rabbit gamete model because rabbit fertilization follows paternal pattern of centrosome inheritance. First, rabbit spermatids and spermatozoa were injected into oocytes using a piezo-micromanipulator. Next, the centrosomal function to form a sperm aster was determined. Furthermore, two functional centrosome proteins (,-tubulin and centrin) of the rabbit spermatogenic cells were examined. Our results show that the oocyte activation rates by spermatozoa, elongated spermatids, and round spermatids were 86% (30/35), 30% (11/36), and 5% (1/22), respectively. Sperm aster formation rates after spermatozoa, elongated spermatids, and round spermatids injections were 47% (14/30), 27% (3/11), and 0% (0/1), respectively. The aster formation rate of the injected elongating/elongated spermatids was significantly lower than that of the mature spermatozoa (P,=,0.0242). Moreover, sperm asters were not observed in round spermatid injection even after artificial activation. These data suggest that poor centrosomal function, as measured by diminished aster formation rates, is related to the poor fertilization rates when immature spermatogenic cells are injected. Mol. Reprod. Dev. 76: 270,277, 2009. © 2008 Wiley-Liss, Inc. [source]

Premature translation of transition protein 2 mRNA causes sperm abnormalities and male infertility

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 3 2007
Khailun Tseden
Abstract During mammalian spermiogenesis somatic histones are replaced at first by transition proteins, which are in turn replaced by the protamines, forming the sperm nucleoprotamines. It is believed that transition protein 2 (Tnp2) is necessary for maintaining the normal processing of protamines and, consequently, the completion of chromatin condensation. The transition protein mRNAs are stored in translationally inert messenger ribonucleoprotein particles for up to 7 days until translational activation in elongated spermatids. Substantial evidence suggests an involvement of 3,untranslated region (UTR) in the translational regulation of the Tnp2 mRNAs. In order to determine the role of Tnp2 3,UTR in translational regulation and to study whether the translational repression of Tnp2 mRNA is necessary for normal spermatid differentiation in mice, we generated transgenic mice that carry a Tnp2-hGH transgene. In this transgene, 3,UTR of Tnp2 gene was replaced by 3, 3,UTR of human growth hormone gene. In these transgenic animals, transcription and translation of Tnp2 occur simultaneously in round spermatids which is an evidence for involvement of Tnp2 3,UTR in its translation repression. Premature translation of Tnp2 mRNA caused abnormal head morphogenesis, reduced sperm motility and male infertility. These results show clearly that a strict temporal and stage-specific Tnp2 translation is necessary for the correct differentiation of round spermatids into mature spermatozoa and for male fertility. Mol. Reprod. Dev. © 2006 Wiley-Liss, Inc. [source]