Laura Giojalas | Universidad Nacional de Córdoba (original) (raw)

Papers by Laura Giojalas

l Starvation effect on reproductive efficiency in males of Triatoma fnfestans Klug., 1834 (Hemipt... more l Starvation effect on reproductive efficiency in males of Triatoma fnfestans Klug., 1834 (Hemiptera, Reduviidae). Starvation incidence on T. infestans male reproduction, has been studied. It was de termi-ned the'measure in which lack of feeding affects eggs' fertility and spermatophore pro-duction. It was also studied the recuperation grade respect to foo$availability after an extended fast. Once the results were evaluated the conclusions obtaiti@'are: 1) Extended fast, significantly disminishes reproductive efficience on T. infestans iTiales; 2) Eggs' fer-tility is not affected; 3) The number of spermatophores formed is reduced, due to the important diminution in the accesory glads secretion which forms the spermatophore; 4) In case of fasting, the blood stored which is present when it changes to the adult stage, has importance on male effective copulation; 5) Blood availability, after an extended fast, permits reproductive recovery only on males which succeeded fe...

Transactions of the Royal Society of Tropical Medicine and Hygiene

This paper examines the infection rate of Trypanosoma cruzi in Triatoma infestans, the main vecto... more This paper examines the infection rate of Trypanosoma cruzi in Triatoma infestans, the main vector of Chagas disease in Argentina and neighbouring countries. The study was carried out in 1986-1987 on 5 houses (ranchos) in the endemic area of central Argentina. Domestic T. infestans populations were sampled in each season with a constant capture effort (2.5 man-hours/house) using a chemical irritant. The rectal content of the bugs was examined for the presence of T. cruzi. The vector population density showed seasonal changes with highest values during the hot season (November-April). The percentage of infected bugs was higher in mid-spring (November) and autumn (April) than in winter (August) and early spring (October). The mean number of parasites (epimastigotes and trypomastigotes) per microliter of rectal material was very high during mid- and late spring (December). The percentage and number of metacyclic forms differed between seasons, reaching the highest values in late spring...

REPRODUCTION, 2012

In mammals, only a few spermatozoa arrive at the fertilization site. During the last step in the ... more In mammals, only a few spermatozoa arrive at the fertilization site. During the last step in the journey to the egg, apart from their self-propulsion, spermatozoa may be assisted by oviduct movement and/or a guidance mechanism. The proportion of rabbit spermatozoa that arrive at the fertilization site was determined under in vivo conditions, in which either the ovulation products (secreting chemoattractants) and/or the oviduct movement (causing the displacement of the oviductal fluid) was inhibited. When only one of these components was inhibited, sperm transport to the fertilization site was partially reduced. However, when both the ovulation products and the oviduct movement were inhibited, almost no spermatozoa arrived at the fertilization site. The results suggest that spermatozoa are transported to and retained at the fertilization site by the combined action of a chemical guidance and the oviduct movement. A working model is proposed to explain how these two mechanisms may ope...

Nature Reviews Molecular Cell Biology, 2006

Memórias do Instituto Oswaldo Cruz, 1992

Journal of Insect Physiology, 1993

Human Reproduction, 2005

BACKGROUND: Human sperm chemotaxis to pre-ovulatory follicular fluid is well established in vitro... more BACKGROUND: Human sperm chemotaxis to pre-ovulatory follicular fluid is well established in vitro. However, it is not known whether the female's oocyte-cumulus complex secretes sperm chemoattractants subsequent to ovulation (for enabling sperm chemotaxis within the Fallopian tube) and, if so, which of these cell types-the oocyte or the cumulus oophorus-is the physiological origin of the secreted chemoattractant. METHODS: By employing a directionality-based chemotaxis assay, we examined whether media conditioned with either individual, mature (metaphase II) human oocytes or the surrounding cumulus cells attract human sperm by chemotaxis. RESULTS: We observed sperm chemotaxis to each of these media, suggesting that both the oocyte and the cumulus cells secrete sperm chemoattractants. CONCLUSIONS: These observations suggest that sperm chemoattractants are secreted not only prior to ovulation within the follicle, as earlier studies have demonstrated, but also after oocyte maturation outside the follicle, and that there are two chemoattractant origins: the mature oocyte and the surrounding cumulus cells.

Fertility and Sterility, 2010

Fertility and Sterility, 2004

Developmental Biology, 2003

Frontiers in Bioscience a Journal and Virtual Library, Jan 5, 2008

Research in Veterinary Science, Feb 28, 2007

Semen quality analysis constitutes a powerful tool to evaluate the fertility potential of males i... more Semen quality analysis constitutes a powerful tool to evaluate the fertility potential of males in threatened species. The Argentine boa constrictor or lampalagua (Boa constrictor occidentalis) is a threatened snake species and has been included in Appendix I of CITES. The objective of this work is to characterize the sperm of B. c. occidentalis on the bases of dynamic parameters to improve this species conservation. Dynamic parameters were measured in sperm samples using videomicroscopy and image analysis software. The sperm population showed a high degree of heterogeneity in velocity parameter values and 95% of the cells showed a linear pattern of movement. Studies in other species indicate that the number of motile spermatozoa and their movement speed is directly correlated with fertilization success. This work will help to establish basic parameter values for the evaluation of the reproductive potential of populations of B. c. occidentalis and to resolve questions referred to its reproductive strategies.

El objetivo general del proyecto es estudiar el efecto de la progesterona y de algunas proteinas ... more El objetivo general del proyecto es estudiar el efecto de la progesterona y de algunas proteinas del plasma seminal sobre la actividad del Ca2+ en diferentes procesos fisiologicos que ocurren en el espermatozoide, los cuales estan estrechamente relacionados con la capacidad fertilizante de esta celula. La progesterona, principal esteroide secretado por las celulas del cumulus oophorus, ejerce su efecto a traves de un receptor no-genomico provocando aumento en el calcio intracelular de los espermatozoides y, consecuentemente, promoviendo la capacitacion, la respuesta quimiotactica y la exocitosis acrosomal. Pese a estas observaciones, los mecanismos a traves de los cuales la progesterona estimula fenomenos tan diversos en el espermatozoide son aun desconocidos. Tampoco se conoce con exactitud el papel funcional y los mecanismos de accion de algunas proteinas del plasma seminal que interaccionan y se unen a los espermatozoides, con alta especificidad, durante la eyaculacion. Por lo tanto, resulta altamente interesante profundizar los estudios sobre las propiedades funcionales de las proteinas caltrin (calcium transport inhibitor) y s-microseminoprotein (MSP) del plasma seminal de mamiferos, las cuales responden a las caracteristicas mencionadas. Los estudios hasta ahora realizados han dado cuenta de que caltrin inhibe la incorporacion de Ca2+ extracelular, previene la exocitosis acrosomal espontanea y promueve la union espermatozoide-zona pelucida. Tambien hay datos preliminares que sugieren un efecto inhibitorio sobre la movilidad hiperactivada de los espermatozoides. Respecto a MSP, solo se sabe que inhibe la exocitosis acrosomal espontanea y que su contenido, en el plasma seminal, guarda una relacion inversa con la fertilidad. Por todo lo expuesto, se propone estudiar los mecanismos de accion de la progesterona y las proteinas caltrin y MSP sobre los procesos fisiologicos antes indicados. Para ello, se estudiaran las variaciones de Ca2+ intracelular en espermatozoides individuales sometidos a diferentes tratamientos (gradientes de progesterona, capacitacion en presencia y ausencia de caltrin y/o MSP, etc.), usando video microscopia de fluorescencia y analisis computarizado de imagenes. Tambien se examinara la influencia de estas moleculas sobre la interaccion de gametas y la fertilizacion.

Journal of Cell Biology, 2015

Ca2+-dependent mechanisms are critical for successful completion of fertilization. Here, we demon... more Ca2+-dependent mechanisms are critical for successful completion of fertilization. Here, we demonstrate that CRISP1, a sperm protein involved in mammalian fertilization, is also present in the female gamete and capable of modulating key sperm Ca2+ channels. Specifically, we show that CRISP1 is expressed by the cumulus cells that surround the egg and that fertilization of cumulus–oocyte complexes from CRISP1 knockout females is impaired because of a failure of sperm to penetrate the cumulus. We provide evidence that CRISP1 stimulates sperm orientation by modulating sperm hyperactivation, a vigorous motility required for penetration of the egg vestments. Moreover, patch clamping of sperm revealed that CRISP1 has the ability to regulate CatSper, the principal sperm Ca2+ channel involved in hyperactivation and essential for fertility. Given the critical role of Ca2+ for sperm motility, we propose a novel CRISP1-mediated fine-tuning mechanism to regulate sperm hyperactivation and orienta...

Revista de biología tropical, 2014

Several sperm parameters have been employed as useful tools to evaluate fish fertility. Within te... more Several sperm parameters have been employed as useful tools to evaluate fish fertility. Within teleosts, approximately 3% of fish species are known to be viviparous. The Order Cyprinodontiformes includes several species with internal fertilization, and within this group most of the studies about sperm quality have been mainly focused on the Poeciliidae family. The livebearing fish Jenynsia multidentata (Anablepidae) inhabits an extensive area of the Neotropical region and it has been used as a useful fish laboratory model to evaluate the effects of xenobiotics through different biomarkers. The present work characterized the sperm of this species through a simple protocol of semen collection. Sperm population showed linearity greater than 89% and 70% of fish have a straight line and curvilinear velocity valued between 50 and 100 μm/s. Although 85% of individuals showed a proportion of live sperm higher than 60%, the male population had a high degree of heterogeneity in its sperm coun...

Ecology and evolution, 2014

In polyandrous species, sperm morphometry and sperm velocity are under strong sexual selection. A... more In polyandrous species, sperm morphometry and sperm velocity are under strong sexual selection. Although several hypotheses have been proposed to explain the role of sperm competition in sperm trait variation, this aspect is still poorly understood. It has been suggested that an increase in sperm competition pressure could reduce sperm size variation or produce a diversity of sperm to maximize male fertilization success. We aim at elucidating the variability of sperm morphometric traits and velocity in two Tupinambis lizards in the context of sperm competition risk. Sperm traits showed substantial variation at all levels examined: between species, among males within species, and within the ejaculate of individual males. Sperm velocity was found to be positively correlated with flagellum: midpiece ratio, with relatively longer flagella associated with faster sperm. Our results document high variability in sperm form and function in lizards.