Analysis and gonadal localization of Speedy A mRNA transcript, a novel gene associated with early germline cells in the scallop, Argopecten purpuratus.

The Speedy A (spdya) gene is a member of the Speedy/RINGO family, encoding a spdya protein associated with cellular cycle and meiosis in vertebrates. Results from genetic analyses indicated spdya conditional knockout mice are sterile, suggesting that this protein has essential functions in mammalian reproduction. There, however, are no published reports on the localization of spdya mRNA in the germline or in somatic cell lineages within the gonads from mollusks or other invertebrate species. Using a previously obtained transcriptome assembly from the scallop Argopecten purpuratus, an economically important hermaphroditic scallop species from Chile and Peru, there was identification of a complete coding sequence of the spdya mRNA. Phylogenetically spdya protein has sequence conservation homology with other scallops and mollusks. The relative mRNA transcript abundances at different gametogenic stages was assessed using quantitative PCR procedures. Results indicated there was an increase of spdya mRNA transcript abundance in testicular region samples at the late active stage, followed by a decrease in testis of reproductively mature individuals. To gain insight into the cellular localization of ap-spdya transcript within the gonads, specific RNA probes were synthesized for in situ hybridization analyses of gonad histological sections. Results indicated spdya mRNA is located exclusively in early germline (previtellogenic oocytes and spermatogonia) and somatic proliferative tissues of A. purpuratus ovarian and testicular regions. Overall, these results indicate there are putative functions of spdya in the early oogenesis and spermatogenesis of A. purpuratus and will contribute to furthering the understanding of gametogenesis in this species.

Endocrine integration of fetal ovaries grafted under kidney capsule of unilaterally or bilaterally orchidectomized male hamster / Integración endocrina de ovarios fetales trasplantados bajo la cápsula renal de hámster machos uni o bilateralmente castrados

Mammalian ovary development undergoes important changes during the perinatal period, moment when follicles are assembled and start to develop in a process not well known, involving endocrine and paracrine factors. In order to investigate the effect of two different hormonal environments on the early development of the ovary, we used an autologous transplant model in which Syrian hamster fetal ovaries were grafted under the kidney capsule of males hosts previously unilaterally or bilaterally orchidectomized. After 35 days of graft, ovaries and kidney parenchyme of the host male did not present signs of rejection. Ovaries contained primordial, primary follicles, secondary follicles and few tertiary follicles with morphological features similar to ovaries of control females of 35 days of age. Healthy primary and secondary follicles of experimental groups had frequency distribution and size similar to control ovaries but tertiary follicles were scarce in control as well as in grafts where they were mainly atretic. PCNA, marker of proliferation, was immuno detected in granulosa cells of growing follicles and the marker of apoptosis, Caspase 3 active, was evident mainly in secondary follicles. Immunoreactivity for steroidogenic proteins, StAR, 3-bHSD and aromatase detected in the follicular wall cells and the decreased serum levels of FSH without important changes in testosterone in bilateral orchidectomized males that received ovarian graft, and testosterone decreased without changes in FSH levels in unilateral orchidectomized males (UO) with ovarian graft, all together suggest the effect of steroid hormones produced by the ovary. In conclusion, the experimental model of autologous transplant presents evidence of early ovary development under the kidney capsule and its functional integration to the endocrine axis of the host male.

El desarrollo del ovario en mamíferos sufre importantes cambios durante el periodo perinatal, momento en el cual los folículos se ensamblan y comienzan a desarrollarse en un proceso no muy dilucidado que involucra señales endocrinas y paracrinas. Con el objetivo de investigar el efecto de dos ambientes hormonales sobre el desarrollo temprano del ovario de hamster, usamos un modelo de trasplante autólogo en el que ovarios fetales fueron trasplantados bajo la cápsula renal de machos receptores previamente castrados y hemicastrados. Después de 35 días de trasplante, los ovarios y el parénquima renal de los machos receptores no presentaron señales de rechazo. El ovario presentó folículos primordiales, primarios, secundarios y algunos folículos terciarios con características morfológicas similares a los ovarios de hembras controles de 35 días de edad. Folículos primarios y secundarios sanos de ambos grupos experimentales se encontraron en frecuencia y tamaño similar al de ovarios controles, los folículos terciarios fueron escasos tanto en controles como en ovarios trasplantados, siendo en éstos principalmente atrésicos. PCNA, un marcador de proliferación celular, fue detectado por inmunohistoquímica en células granulosas de folículos en crecimiento, mientras que caspasa 3 activa, un marcador de apoptosis, fue evidente en folículos secundarios. Por otra parte, inmunoreactividad para proteínas esteroidogénicas, StAR, 3-bHSD y aromatasa, fue detectada en la pared folicular. Esta observación, junto a la disminución de niveles séricos de FSH, sin cambios importantes en los niveles de testosterona en machos castrados que recibieron trasplantes ováricos, y la disminución en los niveles de testosterona sin cambios en los niveles de FSH en machos hemicastrados con trasplantes ováricos, sugiere que el ovario no solo produce hormonas esteroidales sino que además éstas modifican los niveles hormonales del macho receptor del trasplante. En conclusión, este modelo de trasplante autólogo agrega información del desarrollo ovárico temprano cuando éste se desarrolla bajo la cápsula renal de machos entregando evidencia de la integración funcional del ovario trasplantado al eje endocrino de los machos receptores.

In vivo ß-adrenergic blockade by propranolol prevents isoproterenol-induced polycystic ovary in adult rats.

Increasing evidence in animal models and in humans shows that sympathetic nerve activity controls ovarian androgen biosynthesis and follicular development. Thus, sympathetic nerve activity participates in the follicular development and the hyperandrogenism characteristics of polycystic ovary syndrome, which is the most prevalent ovarian pathology in women during their reproductive years. In this study, we mimic sympathetic nerve activity in the rat via "in vivo" stimulation with isoproterenol (ISO), a ß-adrenergic receptor agonist, and test for the development of the polycystic ovary condition. We also determine whether this effect can be reversed by the administration of propranolol (PROP), a ß-adrenergic receptor antagonist. Rats were treated for 10 days with 125 µg/kg ISO or with ISO plus 5 mg/kg PROP. The ovaries were examined 1 day or 30 days following drug treatment. While ISO was present, the ovaries had an increased capacity to secrete androgens; ISO + PROP reversed this effect on androgen secretory activity. 30 days after treatment, androstenedione secretion reverted to normal levels, but an increase in the intra-ovarian nerve growth factor (NGF) concentration and luteinizing hormone (LH) plasma levels was detected. ISO treatment resulted in follicular development characterized by an increased number of pre-cystic and cystic ovarian follicles; this was reversed in the ISO + PROP group. The lack of change in the plasma levels of progesterone, androstenedione, testosterone, or estradiol and the increased LH plasma levels strongly suggests a local intra-ovarian effect of ISO indicating that ß-adrenergic stimulation is a definitive component in the rat polycystic ovary condition.

Photoperiodic modulation of GnRH mRNA in the male Syrian hamster.

Male Syrian hamsters (Mesocricetus auratus) are seasonal breeders. They show marked testicular regression when exposed to short autumnal photoperiods, and then remain sexually quiescent for several months. By mid-winter, however, they show a loss in responsiveness to the inhibitory influence of short photoperiods and their testes begin to recrudesce. To shed light on the neuroendocrine mechanism responsible for mediating these reproductive changes, we examined the influence of photoperiod on the expression of GnRH mRNA in the hamster forebrain. Adult males were either exposed to short photoperiods (6L:18D) for 16 weeks or were maintained under long photoperiods (14L:10D); additional animals were exposed to short or long photoperiods for 22 weeks. As expected, exposure to short photoperiods for 12 weeks resulted in a marked decrease (P<0.01) in testicular mass and serum testosterone levels, but after 22 weeks these reproductive parameters were once again significantly elevated (P<0.01). In contrast, quantitative in situ hybridization histochemistry revealed no difference (P>0.05) between the GnRH mRNA levels of the short-photoperiod hamsters and their aged-matched long-photoperiod controls, although an age-related decrease (P<0.05) was evident in both photoperiod-treatment groups. These data emphasize that GnRH mRNA is highly expressed in hamsters even when their reproductive axis has been rendered sexually quiescent by exposure to short photoperiods, and that photoperiod-induced changes in GnRH secretion, rather than synthesis, are more likely to regulate the timing of the breeding season. On the other hand, the data indicate that GnRH mRNA levels show an aging-related decrease, regardless of photoperiod, suggesting that in the long term a decrease in GnRH gene expression may contribute to the reduced fertility of old hamsters.

Testicular organization and spermatogenesis in Tegula (Chlorostoma) tridentata (Potiez and Michaud, 1838) (Mollusca: Archaeogastropoda: Trochidae).

The basic environment for the generation of spermatozoa in the gastropods is a gametogenic compartment resulting from somatic and germ cells interaction. In arachaeogastropods however, such association has not been characterized. In this study at the light and transmission electron microscopy level, evidences are given that in T. (C.) tridentata, spermatogenesis is centrifugal and occurs around seminiferous tubules surrounding the lumen that is a blood vessel. This basic organization presents somatic cells interacting with germ cells. There are three types of spermatogonia: primary spermatocytes with proacrosomic granules, and spermatids that undergo the following spermiohistogenic events: 1. Nuclear chromatin condensation to form a short cylindrical nucleus with an anterior invagination containing the base of the axial rod and a posterior invagination containing the proximal centriole. 2. Polarization of mitochondria attached to the posterior nuclear membrane to integrate the midpiece. 3. Coalescence of proacrosomic granules in one acrosomic vesicle, polarization of the acrosomic vesicle in the anterior nuclear region and transformation of the acrosomic vesicle in the conical acrosomic complex with a subacrosomic cavity containing the axial rod. 4. Tail formation from the distal centriole. Apparently the supporting cells do not associate closely with the spermatids. Therefore, they would not perform a mechanical role in the generation of spermatozoa shape that is characteristic of the Trochidae and other archaeogastropod families. This spermatozoon is peculiar due to its prominent acrosome larger than the nucleus.

Testicular organization and spermatogenesis in Tegula (Chlorostoma) tridentata (Potiez and Michaud, 1838) (Mollusca: Archaeogastropoda: Trochidae).

The basic environment for the generation of spermatozoa in the gastropods is a gametogenic compartment resulting from somatic and germ cells interaction. In arachaeogastropods however, such association has not been characterized. In this study at the light and transmission electron microscopy level, evidences are given that in T. (C.) tridentata, spermatogenesis is centrifugal and occurs around seminiferous tubules surrounding the lumen that is a blood vessel. This basic organization presents somatic cells interacting with germ cells. There are three types of spermatogonia: primary spermatocytes with proacrosomic granules, and spermatids that undergo the following spermiohistogenic events: 1. Nuclear chromatin condensation to form a short cylindrical nucleus with an anterior invagination containing the base of the axial rod and a posterior invagination containing the proximal centriole. 2. Polarization of mitochondria attached to the posterior nuclear membrane to integrate the midpiece. 3. Coalescence of proacrosomic granules in one acrosomic vesicle, polarization of the acrosomic vesicle in the anterior nuclear region and transformation of the acrosomic vesicle in the conical acrosomic complex with a subacrosomic cavity containing the axial rod. 4. Tail formation from the distal centriole. Apparently the supporting cells do not associate closely with the spermatids. Therefore, they would not perform a mechanical role in the generation of spermatozoa shape that is characteristic of the Trochidae and other archaeogastropod families. This spermatozoon is peculiar due to its prominent acrosome larger than the nucleus.

Testicular organization and spermatogenesis in Tegula (Chlorostoma) tridentata (Potiez and Michaud, 1838) (Mollusca: Archaeogastropoda: Trochidae).

The basic environment for the generation of spermatozoa in the gastropods is a gametogenic compartment resulting from somatic and germ cells interaction. In arachaeogastropods however, such association has not been characterized. In this study at the light and transmission electron microscopy level, evidences are given that in T. (C.) tridentata, spermatogenesis is centrifugal and occurs around seminiferous tubules surrounding the lumen that is a blood vessel. This basic organization presents somatic cells interacting with germ cells. There are three types of spermatogonia: primary spermatocytes with proacrosomic granules, and spermatids that undergo the following spermiohistogenic events: 1. Nuclear chromatin condensation to form a short cylindrical nucleus with an anterior invagination containing the base of the axial rod and a posterior invagination containing the proximal centriole. 2. Polarization of mitochondria attached to the posterior nuclear membrane to integrate the midpiece. 3. Coalescence of proacrosomic granules in one acrosomic vesicle, polarization of the acrosomic vesicle in the anterior nuclear region and transformation of the acrosomic vesicle in the conical acrosomic complex with a subacrosomic cavity containing the axial rod. 4. Tail formation from the distal centriole. Apparently the supporting cells do not associate closely with the spermatids. Therefore, they would not perform a mechanical role in the generation of spermatozoa shape that is characteristic of the Trochidae and other archaeogastropod families. This spermatozoon is peculiar due to its prominent acrosome larger than the nucleus.

Testicular organization and spermatogenesis in Tegula (Chlorostoma) tridentata (Potiez and Michaud, 1838) (Mollusca: Archaeogastropoda: Trochidae)

The basic environment for the generation of spermatozoa in the gastropods is a gametogenic compartment resulting from somatic and germ cells interaction. In arachaeogastropods however, such association has not been characterized. In this study at the light and transmission electron microscopy level, evidences are given that in T. (C.) tridentata, spermatogenesis is centrifugal and occurs around seminiferous tubules surrounding the lumen that is a blood vessel. This basic organization presents somatic cells interacting with germ cells. There are three types of spermatogonia: primary spermatocytes with proacrosomic granules, and spermatids that undergo the following spermiohistogenic events: 1. Nuclear chromatin condensation to form a short cylindrical nucleus with an anterior invagination containing the base of the axial rod and a posterior invagination containing the proximal centriole. 2. Polarization of mitochondria attached to the posterior nuclear membrane to integrate the midpiece. 3. Coalescence of proacrosomic granules in one acrosomic vesicle, polarization of the acrosomic vesicle in the anterior nuclear region and transformation of the acrosomic vesicle in the conical acrosomic complex with a subacrosomic cavity containing the axial rod. 4. Tail formation from the distal centriole. Apparently the supporting cells do not associate closely with the spermatids. Therefore, they would not perform a mechanical role in the generation of spermatozoa shape that is characteristic of the Trochidae and other archaeogastropod families. This spermatozoon is peculiar due to its prominent acrosome larger than the nucleus.

Testicular organization and spermatogenesis in Tegula (Chlorostoma) tridentata (Potiez and Michaud, 1838) (Mollusca: Archaeogastropoda: Trochidae)

The basic environment for the generation of spermatozoa in the gastropods is a gametogenic compartment resulting from somatic and germ cells interaction. In arachaeogastropods however, such association has not been characterized. In this study at the light and transmission electron microscopy level, evidences are given that in T. (C.) tridentata, spermatogenesis is centrifugal and occurs around seminiferous tubules surrounding the lumen that is a blood vessel. This basic organization presents somatic cells interacting with germ cells. There are three types of spermatogonia: primary spermatocytes with proacrosomic granules, and spermatids that undergo the following spermiohistogenic events: 1. Nuclear chromatin condensation to form a short cylindrical nucleus with an anterior invagination containing the base of the axial rod and a posterior invagination containing the proximal centriole. 2. Polarization of mitochondria attached to the posterior nuclear membrane to integrate the midpiece. 3. Coalescence of proacrosomic granules in one acrosomic vesicle, polarization of the acrosomic vesicle in the anterior nuclear region and transformation of the acrosomic vesicle in the conical acrosomic complex with a subacrosomic cavity containing the axial rod. 4. Tail formation from the distal centriole. Apparently the supporting cells do not associate closely with the spermatids. Therefore, they would not perform a mechanical role in the generation of spermatozoa shape that is characteristic of the Trochidae and other archaeogastropod families. This spermatozoon is peculiar due to its prominent acrosome larger than the nucleus.

Molecular Origin of Io's Fast Sodium.

Neutral sodium emissions encircling Jupiter exhibit an intricate and variable structure that is well matched by a simple loss process from Io's atmosphere. These observations imply that fast neutral sodium is created locally in the Io plasma torus, both near Io and as much as 8 hours downstream. Sodium-bearing molecules may be present in Io's upper atmosphere, where they are ionized by the plasma torus and swept downstream. The molecular ions dissociate and dissociatively recombine on a short time scale, releasing neutral fragments into escape trajectories from Jupiter. This theory explains a diverse set of sodium observations, and it implies that molecular reactions (particularly electron impact ionization and dissociation) are important at the top of Io's atmosphere.