Comparative Study of Spermatogenesis and Nucleolar Behavior in Testicular Lobes of Euschistus Heros (Heteroptera: Pentatomidae)

Hindawi Publishing Corporation Psyche Volume 2010, Article ID 428673, 10 pages doi:10.1155/2010/428673 Research Article Comparative Study of Spermatogenesis and Nucleolar Behavior in Testicular Lobes of Euschistus heros (Heteroptera: Pentatomidae) Hederson Vinicius de Souza and Mary Massumi Itoyama Laboratorio´ de Citogenética e Molecular de Insetos (LACIMI), Departamento de Biologia, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP), Rua Cristov´ ao˜ Colombo, 2265, Jardim Nazareth, CEP: 15054-000 Sao˜ JosédoRio Preto, SP, Brazil Correspondence should be addressed to Mary Massumi Itoyama, [email protected] Received 23 March 2010; Accepted 17 June 2010 Academic Editor: Coby Schal Copyright © 2010 H. V. de Souza and M. M. Itoyama. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In some testicular lobes of the Pentatomidae there may be occurrence of atypical spermatogenesis or polymegaly, leading to the production of nonfertile sperm. The comparative analysis of spermatogenesis and nucleolar behavior in testicular lobes of Euschistus heros showed cells with polymegaly in lobes 4 and 6. Generally, when these lobes are present in the same individual, there is also the formation of atypical cells in the flanking lobe. Such characteristic was not seen in E. heros.However,differences regarding the concentration of heteropyknotic chromatin and silver-positive bodies in this lobe deserve attention. This study explored the literature and demonstrated the prevalence of some lobes in the formation of differentiated cells. It was also found in the literature that there is an association of the chromocenter with the nucleolus in several species of Pentatomidae, but in E. heros this association does not appear to occur. 1. Introduction which makes it difficult to establish an evolutionary pattern among testicular lobes with regard to the formation of fertile The presence of testes formed by a number of compartments and nonfertile sperm. For this reason, the data found in the referred to as “lobes” is a characteristic of the Heteroptera. literature are compiled in Table 1. In some species, one of these lobes is of the harlequin type Recent studies have demonstrated the importance of that differs from the other lobes by showing spermatogonial examining the metabolic differences among species by the cells with meiotic pairing, nonspecific association of the analysis of nucleolar bodies. It is known that the nucleolus autosomal bivalents, anomalous arrangement of the chro- or nucleolar bodies are related to the biosynthetic activity of mosomes in the metaphase plate, anomalous chromosome the cell, so that the size and number of bodies depend on the segregation, and cell fusion, resulting in the production of functional characteristics of cells and may therefore reflect spermatozoa with highly variable chromosome numbers. metabolic and functional differences [3–7]. There are reports of this type of lobe in 15 genera in three Another aspect of nucleolar behavior in spermatogenesis Pentatomidae subfamilies (Discocephalinae, Edessinae, and is that, over time, several observations have suggested that Pentatominae) [1]. the nucleolar granules or bodies which persist at the end of Other lobes may also be associated with the formation meiosis reorganize the nucleolus in early spermiogenesis and of nonfertile sperm; for example, in Antiteuchus tripterus support protein synthesis in the process [8]. (Pentatomidae), lobes 4 and 6 show cells with polymegaly The study of metabolic differences between testicular and significant intralobular metabolic differences [2, 3]. lobes with analysis of nucleolar bodies has been proposed The aspects regarding the number of testicular lobes by Souza et al. [3], who found that the testicular lobes and the formation of atypical sperm are little known and of A. tripterus showed significant differences in behavior explored. This information is found scattered in the literature and size of the nucleolar bodies, which may be due to 2 Psyche are associated with rRNA and which can therefore localize DR the nucleolus or nucleolar bodies. 1 2 In the statistical analysis, measurements were taken of 3 the diameter of 100 cells and their nuclei in the diffuse 4 5 stage, that is, the stage after pachytene, which is characterized 6 by its increased size and chromatin scattered throughout the nuclei, and of 100 cells nuclei in the stage of round spermatid in each lobe, randomly chosen. We used the program UTHSCSA Image Tool v.3.00 [48] and Minitab version 15.1 [49] for ANOVA (Tukey’s comparison with PR 95% confidence interval) to compare the measurements of the cells between the testicular lobes. The best images were captured with a Zeiss microscope using the image analysis program AXIO VISION. ED (a) (b) 3. Results Figure 1: Testis of Euschistus heros enclosed by red membrane, 3.1. Testis Morphology. The testes of Euschistus heros were where the proximal region (PR) of the ejaculatory duct (ED) is more enclosed by peritoneal sheath with red pigment, with the intense red than the Distal Region (DR) (a). Observe in (b) the proximal region (PR) of the ejaculatory duct (ED) being presence of six elongated lobes of approximately the same length, with lobe 5 narrower than the others (arrow). Bar = 1 mm. more pigmented than the distal (DR) (Figure 1(a)). When the peritoneal sheath was removed in the distal region, we could observe the presence of 6 elongated lobes of approximately the same length, where lobe 5 was narrower differences in the formation of sperm with a nonfertile than the others (Figure 1(b)). function. The analysis of nucleolar organizer regions (NORs) 3.2. Meiotic Behavior. The comparative analysis of meiotic during prophase has shown a close association of the cells of Euschistus heros stained with lacto-acetic orcein and chromocenter with the nucleolar body [9, 10]. The chromo- silver impregnated showed that the behavior of cells in the six center in Heteroptera is characterized by its heteropyknotic testicular lobes was quite similar, and therefore, the results nature, where it can be composed of sex chromosomes or are presented together. even by heterochromatic autosomes [9, 11, 12]. In general, During early prophase, a heteropyknotic body was the nucleolar body is disorganized during diakinesis [13], observed at the periphery of the nucleus, and variation in reorganizing itself only in the beginning of spermiogenesis, cell diameter among the lobes was the only difference found. supporting the initiation of protein synthesis [8]. How- The diameter of the cells in lobes 1–3 (Figure 2(a)) was ever, the relationship between chromatin heteropyknotic significantly smaller than that of lobe 5 cells (Figure 2(c)), and nucleolar bodies during spermiogenesis has not been which were smaller than cells in lobes 4 and 6 (Figure 2(b)). previously explored, according to the literature. Due to these differences, an ANOVA test was performed, Thus, the objective of this study was to analyze sper- which showed that the lobes could be grouped by the size matogenesisineachlobeofEuschistus heros, comparing it of the cells and their nuclei (Figures 2(a)–2(c)) into three with nucleolar behavior throughout spermatogenesis and different groups (group 1 = lobes 1, 2, and 3, group 2= lobe to analyze in detail the distribution pattern of testicular 5, group 3= lobe 4 and 6). Significant differences (P<.0001) lobes, described in the literature, with regard to differentiated were found between the groups, and the cells of group 1 spermatogenesis. (lobes 1–3) and their nuclei were smaller than those in group 2 (lobe 5) which, in turn, were smaller than those of group 3 2. Material and Methods (lobes 4 and 6) (Table 2). During spermatogenesis, it was observed that the cells in Fifteen adult males of Euschistus heros Fabricius, 1794 (Het- diplotene/diakinesis showed chromosomes with chiasmata eroptera, Pentatomidae, Pentatominae, Pentatomini) were (Figure 2(d)). It was possible to determine in diakinesis collected on soybean plants (Glycine max (L.), in the city of and metaphase I the presence of a diploid number of SaoJosedoRioPreto(20◦4713 S, 49◦2138 W), SP,Brazil. 2n = 14 (12A + XY) chromosomes (Figures 2(d), 2(e)). In The insects were fixed in methanol:acetic acid (3 : 1), and anaphase/telophase I, it was observed that only autosomes their testicular lobes were separated and submitted to the undergo reductional segregation (Figures 2(f), 2(g)). During squash technique with lacto-acetic orcein staining, which is metaphase II, the autosomes were arranged in a ring with chromosome specific. the sex chromosomes arranged inside (Figure 2(h)). Dur- To study nucleolar behavior during spermatogenesis, the ing anaphase/telophase II, the sex chromosomes undergo slides were submitted to the silver impregnation technique equational division and it was possible to visualize lagging [47, with modifications] to stain argyrophilic proteins, which migration of the X chromosome (Figure 2(i)). Psyche 3 Table 1: All species of the family Pentatomidae in the literature where authors noted the number of testicular lobes and if they exhibited atypical meiosis and polymegaly. “No”: characteristic not found; “—”: information not found, “?”: author not sure about the presence of the characteristics. Classification No. lobes Atypical meiosis Polymegaly References Pentatomidae family Subfamily

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