Paulo Ramos da Silva Santos

Evaluation of the genotoxicity of Crotalus durissus terrificus snake venom and its isolated toxins on human lymphocytes

In the present study, experiments were carried out to evaluate the mutagenic potential and genotoxic effects of Crotalus durissus terrificus snake venom and its isolated toxins on human lymphocytes, using the micronucleus and comet assays. Significant damage to DNA was observed for crotoxin and crotapotin (CA). Basic phospholipase A(2) (CB) and crotamine did not present any mutagenic potential when evaluated by the micronucleus test. C. d. terrificus crude venom was able to induce the formation of micronuclei, similarly to the mutagenic drug used as a positive control. In the comet assay, all the toxins tested (crotamine, crotoxin, CB and CA) and C. d. terrificus venom presented genotoxic activity. Studies on the cytogenetic toxicology of animal venoms and their isolated proteins are still very scarce in the literature, which emphasizes the importance of the present work for the identification and characterization of potential therapeutic agents, as well as for the better understanding of the mechanisms of action of toxins on the human body.

Ultrastructure of spermatogenesis in Spix's yellow-toothed cavy (Galea spixii).

This was a pioneer study of the spermatogenic process from the onset of puberty in Spixs yellow-toothed cavies (SYC, Galea spixii) bred in captivity. The study aimed to characterize fine structure of spermatogenesis. Twelve testes from pubertal and post-pubertal SYC males were studied using transmission electron microscopy. Spermatogenesis can be divided into three phases: proliferation, meiosis, and spermiogenesis. In proliferation phase, three types of spermatogonia were identified and characterized as A(dark), A(pale), and B. In the second phase, spermatocytes (2n) undergo meiotic divisions that generate spermatids (n); the process begins in spermatocytes in the preleptotene stage when they increase their nuclear size, differentiating into spermatocytes in the leptotene stage when cell division is initiated. In addition, we found chromatin condensation, and formation of a structure composed of proteins that formed a central shaft and two lateral bars associated with pairing of homologous chromosomes. During spermiogenesis, the following main events occurred: condensation of nuclear chromatin, formation of acrosome with perfuratorium, elimination of residual cytoplasm, and development of the flagellum. The sperm head is different from that of other rodents. The endoplasmic reticulum and the Golgi complex are the two main organelles demonstrated during this process. These organelles collaborate through synthesis of proteins and hormones for the development of germ cells during spermatogenesis in SYC.

Development of spermatogenesis in captive-bred Spix's yellow-toothed cavy (Galea spixii).

The aim of this study was to evaluate the phases of sexual development and spermatogenesis of Spixs yellow-toothed cavy (Galea spixii) based on analyses of the structural components of the testes. The testes of animals from 0 to 150 days of age were collected by orchiectomy, weighed, and processed for analysis by light microscopy. At 45 days of age, spermatozoa were seen in the tubular lumen. Spermatogenesis was not established in animals from 45 to 150 days of age. The stages of sexual development may be classified into the following phases: from birth to the age of 15 days (immature); 30 days of age (prepubertal); 45-105 days of age (pubertal); and 120 and 150 days of age (postpubertal). This is the first study to address the male reproductive biology of Spixs yellow-toothed cavy.

Caracterização morfológica e frequência dos estádios do ciclo do epitélio seminífero em preás (Galea spixii Wagler, 1831) criados em cativeiro

Studies based on the testicular characteristics are strongly associated with the reproductive efficiency of various species. Thus, the developed project aimed to identify the cells of the seminiferous epithelium, histologically characterized their associations, which form stages, and determine the frequency of these. The fragments of testes, 30, 45, 60, 75, 90, 105, 120, 150 days were collected Multiplication Center of Universidade Federal Rural do Semi-Arido, Mossoro, RN. Through the process of fixing, washing in solutions of increasing concentrations of alcohols (70-100%), dehydration in xylene, inclusion in Histosec ®, preparation of histological slides, stained with hematoxylin and eosin (HE) and their photomicrographs for the characterization of cell nuclei of the germinal epithelium and the definition of the eight stages of the seminiferous epithelium cycle (CES) based on the tubular morphology method. The different age groups all animals at 90 to 150 days of age showed all stages of the CES. Stages I and III showed the highest and lowest frequency, respectively. Animals categorized as prepubertal (30 days), pubertal (45 to 90 days old) and postpubertal (105 to 150 days of age) had stage I, IV and VIII with a higher frequency, respectively.

Seasonal variations cause morphological changes and altered spermatogenesis in the testes of viscacha (Lagostomus maximus)

This study complements the previous investigations of the reproductive biology of male viscachas, a rodent of a seasonal Hystricognathi that exhibits photoperiod-induced morphological variations in the reproductive system. In the present study, a quantitative analysis of spermatogenesis was performed during the summer and the spring. Spermatogonial cells were analyzed to determine by immunolabelling for STRA8 and DAZL, which are essential for spermatogenesis. Six free-living male viscachas were captured, three animals in the summer during the period of reproductive activity and three animals in the spring during the period of testicular regression. The testes of the viscachas were collected and processed for light microscopy, macroscopic and immunochemical analyses. The germ and Sertoli cells present in the seminiferous tubules were quantitatively analyzed in each animal. The efficiency coefficient for spermatogonial mitosis, meiotic yield, overall spermatogenesis yield and Sertoli cell index, revealed that the Sertoli cells in male viscachas captured during the summer had a reduced capacity to structurally and nutritionally support the developing round spermatids compared with the male viscachas captured during the spring. The animals produced less sperm during the spring than the summer, suggesting a seasonal impact on spermatogenesis. Immunolabelling for STRA8 and DAZL was detected during summer and spring seasons. These results suggest that in seasonal rodents, such as the male viscachas, the photoperiod promotes significant changes in the testis and in the germ cell yield.

The Correlation between Age, Body Weight and Testicular Parameters in Murrah Buffalo Bulls Raised in Brazil

Abstract Buffalo are an economically important source for meat and milk production, especially in Brazil. However, important aspects of their biology remain unknown thus far. Herein, we describe the reproductive characteristics of male Murrah buffalo (Bubalus bubalis) raised under extensive management conditions by applying biometrics associated with testicular weight. We analyzed seven males, divided into two groups: G1, which consisted of four 18-month-old animals, and G2, which consisted of three 24-month-old animals. Testicular development occurs slowly in Murrah buffalo, suggesting a delay of sexual maturity. The biometric testicular parameters analyzed were scrotal circumference, testicular weight, testicular length, testicular width, testicular thickness and testicular circumference. Our data indicate strong correlations between SC, age and body weight, and additional significant relationships were identified between body weight, age and other testicular parameters. Thus, these parameters are suitable indicators when selecting bulls for breeding purposes.

Descrição morfológica do diafragma do sagui-de-tufo-branco (Callithrix jacchus)

ABSTRACT.- Lessa T.B., Constantino M.V.P., Silva L.C.S., Santos S.R.P., Assis Neto A.C., Miglino M.A, Bombonato P.P. & Ambrosio C.E. 2012. [ Morphological description of diaphragm of white-tufted-ear-marmoset ( Callithrix jacchus ). ] Descricao morfologica do diafragma do sagui-de-tufo-branco ( Callithrix jacchus ). Pesquisa Veterinaria Brasileira 32(6):553-558. Departamento de Cirurgia, Programa de Pos-Graduacao em Anatomia dos Animais Domes-ticos e Silvestres, Faculdade de Medicina Veterinaria, Universidade de Sao Paulo, Av. Prof. Dr. Orlando Marques de Paiva 87, Cidade Universitaria, Sao Paulo, SP 05508 270, Brazil. E-mail: thaisblessa@usp.brThe diaphragm muscle found only in mammals is the main muscle in the respiratory pro-cess, serving as the border between the thoracic and abdominal cavities. Its signiicance also is highlighted in research conducted with grafts using various types of biological membranes for the repair of diaphragmatic defects which may cause diaphragmatic hernias. In spite of many studies already conducted in non-human primates, especially in regard to the new world species

Ultrastructure of spermatogenesis and spermatozoa in agoutis during sexual development

The aim was to study the ultrastructure of testicular parenchyma and define the morphological ultrastructure of spermatozoa of agoutis kept in captivity. Segments of testes from eight agouti males at prepubescence, prepuberty, pubescence and sexual maturity were fixed in glutaraldehyde. Laboratory procedures were performed for transmission electron microscopy. Spermatogonial cells of Type A - pale, Type A - dark, intermediate and Type B were found. Spermatocytes in the pachytene phase were abundant among primary spermatocytes. From the prepubertal phase, Sertoli cells exhibited invaginations in the nuclear membrane and lipid inclusions in the cytoplasm due to their phagocytic function. Leydig cells displayed higher metabolic activity during puberty as evidenced by the presence of lipid droplets. Spermatozoa were fully formed morphologically at prepuberty. The centriolar complex had partially degenerated and featured a centriolar space as in rodents. Sperm heads were tapered, without prominence of the acrosome or evidence of the perforatorium, differing from cavies, rats and mice. This is the first study to describe the ultrastructure of agouti spermatozoa. This research may assist as a basis for future work related to fertility and other biotechnologies applied to reproductive biology in agoutis.

Ultrastructure of the epididymis and vas deferens of agoutis at different stages of sexual development

The agouti (Dasyprocta spp.) is a rodent found predominantly in the Brazilian Caatinga and has importance as an alternative source of protein. In this study, the objective was to describe the ultrastructure of components of sperm pathways, especially the epididymis and vas deferens, during sexual development of agoutis kept in captivity. Segments of the vas deferens and epididymis of 8 agouti males at different stages of sexual development (prepubescent, prepubertal, pubescent, and adult) were fixed in glutaraldehyde. The following laboratory procedures were performed: histology following the standard protocol for semithin cut (toluidine blue), and transmission electron microscopy. This was a pioneer study in which it was observed that the epididymis of agoutis is composed of principal, basal, halogen, apical, and clean cells. During prepubescent and prepubertal stages, clean cells were observed in addition to principal, basal, and halogen cells. Once puberty was reached, apical cells were also present, and clean cells were no longer visible. This epithelial change during sexual development is possibly due to physiological functions. The interaction between these cells supports this, and age probably influenced the change. With regard to the vas deferens, this study was also a pioneer to note that before pubescence there were two muscle layers, differing from older animals, which had three muscle layers. This may be due to lack of sperm transit in younger animals. We concluded that the pseudostratified stereociliated epithelium of the epididymis and vas deferens of agoutis kept in captivity undergo morphological and functional changes during sexual development.

Daily sperm production and evaluation of morphological reproductive parameters of Murrah buffaloes in an extensive breeding system

The development of male sexual maturity varies among buffaloes. The Murrah buffalo is considered the most important and efficient milk and fat producer, but aspects of its reproductive biology are still unknown. The present study aimed to evaluate the daily sperm production (DSP) and spermatogenesis in developing Murrah buffalo bulls by evaluation of the seminiferous tubules, testicular morphometry and using light microscopy and scanning electron microscopy. The testes of Murrah buffalo bulls at 18 mo was immature and at 24 mo could still be considered an average-efficiency breed based on their DSP. At 24 mo, the DSP rate was 0.97 billion sperm per testis and 13 million sperm per gram of testis. However, the animals had superior morphometric parameters compared with those of other livestock animals, except for the seminiferous tubule volume and diameter, which were inferior. In conclusion, our data support former views that the testes of the Murrah breed does not reach sexual maturity before 2 y of age and that important developmental steps occur later than Murrah crossbreeds from Brazil.