Mature Testis Research Articles

Estrogen alters gonadal soma-derived factor (Gsdf)/Foxl2 expression levels in the testes associated with testis-ova differentiation in adult medaka, Oryzias latipes

Testis-ova differentiation in sexually mature male medaka (Oryzias latipes) is easily induced by estrogenic chemicals, indicating that spermatogonia persist in sexual bipotentiality, even in mature testes in medaka. By contrast, the effects of estrogen on testicular somatic cells associated with testis-ova differentiation in medaka remain unclear. In this study, we focused on the dynamics of sex-related genes (Gsdf, Dmrt1, and Foxl2) expressed in Sertoli cells in the mature testes of adult medaka during estrogen-induced testis-ova differentiation. When mature male medaka were exposed to estradiol benzoate (EB; 800ng/L), testis-ova first appeared after EB treatment for 14days (observed as the first oocytes of the leptotene-zygotene stage). However, the testis remained structurally unchanged, even after EB treatment for 28days. Although Foxl2 is a female-specific sex gene, EB treatment for 7days induced Foxl2/FOXL2 expression in all Sertoli cell-enclosed spermatogonia before testis-ova first appeared; however, Foxl2 was not detected in somatic cells in control testes. Conversely, Sertoli-cell-specific Gsdf mRNA expression levels significantly decreased after EB treatment for 14days, and no changes were observed in DMRT1 localization following EB treatment, whereas Dmrt1 mRNA levels increased significantly. Furthermore, after EB exposure, FOXl2 and DMRT1 were co-localized in Sertoli cells during testis-ova differentiation, although FOXL2 localization was undetectable in Sertoli-cell-enclosed apoptotic testis-ova, whereas DMRT1 remained localized in Sertoli cells. These results indicated for the first time that based on the expression of female-specific sex genes, feminization of Sertoli cells precedes testis-ova differentiation induced by estrogen in mature testes in medaka; however, complete feminization of Sertoli cells was not induced in this study. Additionally, it is suggested strongly that Foxl2 and Gsdf expression constitute potential molecular markers for evaluating the effects of estrogenic chemicals on testicular somatic cells associated with estrogen-induced testis-ova differentiation in mature male medaka.

Sex and tissue specific gene expression patterns identified following de novo transcriptomic analysis of the Norway lobster, Nephrops norvegicus

BackgroundThe Norway lobster, Nephrops norvegicus, is economically important in European fisheries and is a key organism in local marine ecosystems. Despite multi-faceted scientific interest in this species, our current knowledge of genetic resources in this species remains very limited. Here, we generated a reference de novo transcriptome for N. norvegicus from multiple tissues in both sexes. Bioinformatic analyses were conducted to detect transcripts that were expressed exclusively in either males or females. Patterns were validated via RT-PCR.ResultsSixteen N. norvegicus libraries were sequenced from immature and mature ovary, testis and vas deferens (including the masculinizing androgenic gland). In addition, eyestalk, brain, thoracic ganglia and hepatopancreas tissues were screened in males and both immature and mature females. RNA-Sequencing resulted in >600 million reads. De novo assembly that combined the current dataset with two previously published libraries from eyestalk tissue, yielded a reference transcriptome of 333,225 transcripts with an average size of 708 base pairs (bp), with an N50 of 1272 bp. Sex-specific transcripts were detected primarily in gonads followed by hepatopancreas, brain, thoracic ganglia, and eyestalk, respectively. Candidate transcripts that were expressed exclusively either in males or females were highlighted and the 10 most abundant ones were validated via RT-PCR. Among the most highly expressed genes were Serine threonine protein kinase in testis and Vitellogenin in female hepatopancreas. These results align closely with gene annotation results. Moreover, a differential expression heatmap showed that the majority of differentially expressed transcripts were identified in gonad and eyestalk tissues. Results indicate that sex-specific gene expression patterns in Norway lobster are controlled by differences in gene regulation pattern between males and females in somatic tissues.ConclusionsThe current study presents the first multi-tissue reference transcriptome for the Norway lobster that can be applied to future biological, wild restocking and fisheries studies. Sex-specific markers were mainly expressed in males implying that males may experience stronger selection than females. It is apparent that differential expression is due to sex-specific gene regulatory pathways that are present in somatic tissues and not from effects of genes located on heterogametic sex chromosomes. The N. norvegicus data provide a foundation for future gene-based reproductive studies.

The contribution of p53 and Y chromosome long arm genes to regulation of apoptosis in mouse testis.

Apoptosis of excessive or defective germ cells is a natural process occurring in mammalian testes. Tumour suppressor protein p53 is involved in this process both in developing and adult male gonads. Its contribution to testicular physiology is known to be modified by genetic background. The aim of this study was to evaluate the combined influence of the p53 and Y chromosome long arm genes on male germ cell apoptosis. Knockout of the transformation related protein 53 (Trp53) gene was introduced into congenic strains: B10.BR (intact Y chromosome) and B10.BR-Ydel (Y chromosome with a deletion in the long arm). The level of apoptosis in the testes of 19-day-old and 3-month-old male mice was determined using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate in situ nick-end labelling (TUNEL) method. The study revealed that although p53 is involved in germ cell apoptosis in peripubertal testes, this process can also be mediated by p53-independent mechanisms. However, activation of p53-independent apoptotic pathways in the absence of the p53 protein requires engagement of the multicopy Yq genes and was not observed in gonads of B10.BR-Ydel-p53-/- males. The role of Yq genes in the regulation of testicular apoptosis seems to be restricted to the initial wave of spermatogenesis and is not evident in adult gonads. The study confirmed, instead, that p53 does participate in spontaneous apoptosis in mature testes.

The morphology of the male reproductive system, spermatogenesis and the spermatozoon of Daphnia magna (Crustacea: Branchiopoda).

This study analyses the histological and cellular morphology of the testis and sperm development in the male Daphnia magna Straus 1820. Due to the rarity of males and predominately parthenogenetic lifecycle of Daphnia, there has been limited detailed information on males in contrast to the well-studied female. Using light and electron microscopy approaches, we describe the morphology of the testis during the progression from an immature to mature testis. The testis has an encasing muscular mesh sheath outside the basal lamina, beneath which is a thin somatic epithelial cell layer. Internal to the epithelium are the spermatogonial stem cells and subsequent syncytial clusters of the germ cells as they progress through spermatogenesis; spermatozoa occupy the entire testis in sexually mature D. magna. We describe the structure of developing and mature spermatozoa; mature spermatozoa are non-flagellated, ovoid in shape with plasmalemma filapodia and are encased in an extracellular capsule.

Male reproductive traits of the marine snail Buccinanops deformis (King, 1832), (Gastropoda: Nassariidae): Size and age at maturity and sperm morphology

Size and age at sexual maturity in males was studied in Buccinanops deformis through analysis of gonadal tissue samples, secondary sexual characters and mating behavior in Golfo San Matías, Patagonia. Gonadal maturity occurred prior to the development of secondary sexual characters. Size at first gonadal maturity was 17.5cm shell length (ca. 3–4 yr) whereas secondary sexual characters as penis length mature in the population at 20.16cm. Four gonadal stages were recorded during the year, and spawning period was identified from June to August (austral winter). Filiform spermatozoa and vermiform paraspermatozoa are present in the mature testis. This study provides new complementary characters by which the systematic of Buccinanops species can be better evaluated. Results are broadly compared with published information of other Neogastropoda.

Identification and profile of microRNAs in Xiang pig testes in four different ages detected by Solexa sequencing

To further understand the role of microRNA (miRNA) during testicular development, we constructed four small RNA libraries from the testes of the Chinese indigenous Xiang pig at four different ages, which were sequenced using high-throughput Solexa deep sequencing methods. It yielded over 23 million high-quality reads and 1,342,579 unique sequences. At two and three months of age, the proportion which represented miRNAs was the most abundant class of small RNAs, but it was gradually replaced by the category that represented piRNAs in adult testes. We identified 543 known and homologous conserved porcine miRNAs and 49 potential novel miRNAs. There were 306 known miRNAs which were co-expressed in four libraries. Six miRNAs and three potential novel miRNAs were validated in testes and sperms of Xiang pig by RT-qPCR method. Many clusters of mature miRNA variants were observed, in which let-7 family was the most abundant one. After comparison among libraries, 204 miRNAs were identified as being differentially expressed and likely involved in the development and spermatogenesis of pig testes. This work presented a general genome-wide expression profile of the testes-expressed small RNAs in different ages of pig testes. Our results suggested that miRNAs performed a role in the regulation of mRNAs in puberty pig testes while piRNAs likely functioned mainly in sexually mature pig testes.

Expression patterns of sex differentiation-related genes during gonadal sex change in the protogynous wrasse, Halichoeres trimaculatus

The three-spot wrasse, Halichoeres trimaculatus, can change sex from female to male (i.e. protogyny) due to sharp decrease in endogenous estrogen. During the sex change, ovarian tissue degenerates and testicular tissue arises newly. Finally, ovarian tissue disappears completely and replaces into mature testis. In order to predict the molecular mechanisms controlling the processes of sex change, we investigated the expression patterns of four genes (rspo1, figla, sox9b and amh), which have been thought to be associated with ovarian/testicular differentiation in vertebrates. Expression levels of rspo1 and figla, which play important roles for ovarian differentiation in vertebrates, were stable until the middle stage of the sex change, and subsequently down-regulated. Therefore, it was indicated that decrease in rspo1 and figla could result from ovarian degeneration. On the other hand, basis on the expression pattern, it was indicated that sox9b and amh, which are involved in testicular differentiation in vertebrates, were implicated in testicular formation and spermatogenesis during the sex change as well. The present results could be fundamental information for investigating the relationship between these factors and E2 depletion, which is crucial trigger for sex change.

Strand-specific RNA sequencing in pig testes identifies developmentally regulated genes and circular RNAs

Testicular development and spermatogenesis are strictly regulated with the complex interactions between several cell types in testis. However, the limited availability of genomic and molecular information limits our understanding of this complex physiological process. In this study, we characterized the transcriptome between immature (30-day-old) and mature (180-day-old) pig testes using RNA-seq technology. 24,469 known coding gene transcripts corresponding to 20,566 genes were mapped in these two developmental stages, 3,328 genes were differentially expressed, and numerous novel transcripts and alternative splicing events were also identified. Ten differentially expressed genes were validated by measuring the relative expression using real-time quantitative polymerase chain reaction (PCR). 125 Gene Ontology (GO) terms were significantly enriched, and most of them involved in GO terms related to male reproduction, testicular development, and spermatogenesis. In addition, this study also represented the prediction of 10,000 circRNAs, as well as the validation of six pig circRNAs using Find_cric algorithm. Our study substantially expanded our knowledge about the transcriptomic profile of immature and mature pig testes, and provided a useful resource to study the mechanisms of pig testis development and spermatogenesis at the molecular level.

Systematic identification and characterization of miRNAs and piRNAs from porcine testes

microRNAs (miRNAs) and PIWI-interacting RNAs (piRNAs) execute important regulatory roles in testis development and spermatogenesis, while previous studies mainly focus on the expression profiles in immature and mature porcine testes, which may cause a bottleneck for further understanding their complex physiological processes in porcine testes development and spermatogenesis. Thus, we presented the expression and characterization of miRNAs and piRNAs in DS (60-day-old), DN (90-day-old), DT (120-day-old) and DF (150-day-old) pig testes. In total, 12,834,628, 13,359,726, 12,851,249 and 12,938,601 clean reads were generated from these libraries, respectively. 293 mature and 36 novel miRNAs as well as 4923 piRNA clusters were identified from pig testes, and they showed an age-dependent manner. GO enrichment analysis of miRNA target genes and piRNA generated genes showed that they participated widely in regulating the pig spermatogenesis process. In addition, 12 differentially expressed miRNAs were randomly selected to validate using qRT-PCR. Our results provided novel comprehensive expression profiles of miRNAs and piRNAs in pig testes at different stages of sexual maturity, which will promote our knowledge of them in regulating the pig testes development and spermatogenesis process.

Histological Characteristics on the Testes of Mud Spiny Lobster, Panulirus polyphagus (Herbst, 1793).

Mud spiny lobsters, Panulirus polyphagus (P. polyphagus) are one of the most important fisheries resources now-a-days due to quality that it's possessed. However, there is still lack of in-depth study about this species mainly on males testicular characteristics and sexual maturity size. Therefore, the present study was carried out to investigate the histological characteristics on the testes and sexual maturity sizes of mud spiny lobster, Panulirus polyphagus. The testes were dissected out and fixed in 10% buffered formalin solution for 11 h, dehydrated in 70% alcohol and lastly placed in tissue processor for 18±1 h at 60°C. The tissues blocks were cut at the thickness of 4 μm on a rotary microtome. Stained tissues were taken under Advance Microscope (Nikon Eclipse 80i Nomarski DIC). Collected data were analyzed using Microsoft Excel 2013. Data were presented as mean±standard deviation. Statistical analyses were done using one-way ANOVA using SPSS (Version 22). These lobules of mature P. polyphagus were formed via different germinative lineage cells such as spermatogonia, spermatocytes, spermatids and spermatozoa. The histological characteristics of testes showed that the process of spermatogenesis went through the stages of four testes maturation which were spermatogonia I and II, spermatocytes I and II, spermatids and spermatozoa stages within different body weight of P. polyphagus. It was found that there were significant difference between body weight and carapace length to the testicular maturation stages (one-way ANOVA and p = 0.000). The results of this experiment indicated that males P. polyphagus have four stages of testes maturation and can be considered to have fully mature testes that ready for fertilization at 452 g body weight (BW) and 107 mm carapace length (CL) or more.

Expression profile of the SOX9 gene in the testes of sexually immature and mature male goats (Capra hircus), and its potential influence on postnatal testis development

The aim of this study was to compare the expression levels of the SOX9 (SRY-box 9) gene in the testes of 18 White improved male goats (Capra hircus) divided into three age groups (one, 10 and 15 months of age with seven, eight and three individuals per group, respectively). Abnormalities in testis development were observed in three individuals from the group of 10-month-olds. Additionally, differences in SOX9 expression that may affect the process of testis maturation and testicular spermatogenic activity were investigated among individuals. The expression of the SOX9 gene in testicular tissues was analysed using qPCR. Maximal SOX9 expression was observed in 10-month-old males with normal testes, while expression was significantly reduced in the same age group of males with abnormal testes. Abnormalities in testis development were associated with low parameters of semen quality. The lowest expression levels of SOX9 were observed in 15-month-old goats. The results of the present study indicate that SOX9 expression changes significantly during the development of male goats.

Sexual dimorphic expression of dnd in germ cells during sex reversal and its requirement for primordial germ cell survival in protogynous hermaphroditic grouper

Dead end (dnd), vertebrate-specific germ cell marker, had been demonstrated to be essential for primordial germ cell (PGC) migration and survival, and the link between PGC number and sex change had been revealed in some teleost species, but little is known about dnd in hermaphroditic vertebrates. In the present study, a protogynous hermaphroditic orange-spotted grouper (Epinephelus coioides) dnd homologue (Ecdnd) was identified and characterized. Quantitative real-time PCR and in situ hybridization analysis revealed a dynamic and sexually dimorphic expression pattern in PGCs and germ cells of gonads. During sex changing, the Ecdnd transcript sharply increased in early transitional gonad, reached the highest level at late transitional gonad stage, and decreased after testis maturation. Visualization of zebrafish PGCs by injecting with RFP-Ecdnd-3'UTR RNA and GFP-zfnanos3-3'UTR RNA confirmed importance of Ecdnd 3'UTR for the PGC distribution. In addition, knockdown of EcDnd by using antisense morpholinos (MO) caused the ablation of PGCs in orange-spotted grouper. Therefore, the current data indicate that Ecdnd is essential for PGCs survival and may serve as a useful germ cell marker during gametogenesis in hermaphroditic grouper.

Impact of a timed-release follicle-stimulating hormone treatment from one to three months of age on endocrine and testicular development of prepubertal bulls.

In prepubertal bulls, FSH facilitates testis maturation and a transient proliferation of Sertoli cells. Two experiments examined the effects of exogenous FSH on hormone secretion and testis development in Angus bulls. Exogenous FSH treatment consisted of an intramuscular injection (i.m.) of 30 mg FSH (Folltropin-V) in a 2% hyaluronic acid solution (FSH-HA). In Exp. 1, bulls (50 ± 6.5 d of age) received either FSH-HA ( = 5) or saline (control; = 5) on d 50 and 53.5. Blood samples were collected via jugular venipuncture to assess FSH concentrations every 6 h for 24 h after treatment and every 12 h until 84 h. After each treatment, peripheral FSH concentrations were greater ( < 0.05) in the FSH-HA-treated bulls than in the control bulls 6 h after treatment and tended to be greater ( ≤ 0.08) 12 h after treatment. The FSH concentration from 18 to 84 h after treatment did not differ between treatments. In Exp. 2, bulls were treated with FSH-HA ( = 11) or saline (control; = 11) every 3.5 d from 35 to 91 ± 2 d of age. Blood samples were collected before each treatment to quantify FSH, testosterone, and activin A concentrations. Scrotal circumference (SC) and BW were measured weekly. Bulls were castrated at 93 ± 2 d of age. Seminiferous tubule diameter, testis composition, and the number of Sertoli cells per tubule cross section (GATA-4 positive staining) were determined from fixed and stained histological sections. Follicle-stimulating hormone concentrations within the FSH-HA-treated bulls increased ( < 0.05) on d 70 from prior sampling and remained elevated. The FSH concentration did not differ between treatments from 35 to 66.5 d of age but were greater ( < 0.05) in the FSH-HA-treated bulls than in the control bulls from 70 to 91 d of age. Serum concentration of activin A on d 35, 70, and 91 did not differ between treatments. The FSH-HA and control bulls did not differ ( > 0.1) in BW, SC, testis weight, testis volume, percent of parenchyma composed of tubules, tubule diameter, and concentration of testosterone. The number of Sertoli cells per tubule cross section was greater in the FSH-HA-treated bulls than in the control bulls (33.35 ± 0.9 vs. 28.27 ± 0.9 cells; ˂ 0.05). In summary, the FSH-HA treatment from 35 to 91 d of age resulted in increased endogenous FSH from 70 to 91 d and increased numbers of Sertoli cells at 93 d of age. Exogenous FSH altered endocrine mechanisms regulating endogenous FSH secretion and augmented Sertoli cell proliferation in young bulls, but this effect was apparently not caused by increased activin A concentration in the FSH-HA-treated bulls.

Comparative morphology of gonads from six species of fish belonging to the family Anostomidae (Characiformes: Anostomidae)

In fishes, gonad morphology is an important parameter to understand the reproductive biology, phylogenetic relationships and systematic studies. The main objective of this study was to make a comparative analysis of the morphology of mature ovary and testis in six fish species of the family Anostomidae. A total of 212 specimens, presenting maturing gonads, were captured from the São Francisco River, Três Marias Reservoir area, in Southeastern Brazil, between August 2008 and December 2010. The six analyzed species had mature ovaries and showed a grayish color. In vitellogenic oocytes (VO), cortical alveoli (CA) were composed by small vesicles in all Leporinus species, but in Leporellus vittatus and Schizodon knerii the CA were large vesicles. However, the CA of all species showed similar histochemical content. The pellucid zone consists of two layers to all species, but it was thicker in S. knerii (11.5 ± 1.8 µm) than in L. vittatus (9.0 ± 0.8 µm) and Leporinus species (3.5 ± 0.6 - 8.7 ± 0.9 µm). Follicular cells of the VO were respectively cubic and prismatic in animal and vegetative poles of S. knerii (22.3 ± 3.2 and 61.1 ± 9.6 µm), and squamous in the other species (1.3 ± 0.3 - 1.6 ± 0.3 µm). Females of S. knerii and males of L. vittatus showed lower values of gonadosomatic index (GSI) than the other assessed species. All evaluated species presented testicular morphology similar to most neotropical Characiformes, with unrestricted spermatogonial testis and anastomosing tubular organization of seminiferous tubules. Phenotypical differences in the vitellogenic oocyte of Anostomidae fishes, confirmed the taxonomic position of S. knerii as different genus in relation to Leporinus and L. vittatus. Despite being placed in different genera, the characteristics of the vitellogenic oocytes of L. vittatus were similar to those found in the studied Leporinus.

TUSC3: a novel tumour suppressor gene and its functional implications.

The tumour suppressor candidate 3 (TUSC3) gene is located on chromosome region 8p22 and encodes the 34 kD TUSC3 protein, which is a subunit of the oligosaccharyl transferase responsible for the N‐glycosylation of nascent proteins. Known to be related to autosomal recessive mental retardation for several years, TUSC3 has only recently been identified as a potential tumour suppressor gene. Based on the structure and function of TUSC3, specific mechanisms in various diseases have been investigated. Several studies have demonstrated that TUSC3 is an Mg2+‐transporter involved in magnesium transport and homeostasis, which is important for learning and memory, embryonic development and testis maturation. Moreover, dysfunction or deletion of TUSC3 exerts its oncological effects as a modulator by inhibiting glycosylation efficiency and consequently inducing endoplasmic reticulum stress and malignant cell transformation. In this study, we summarize the advances in the studies of TUSC3 and comment on the potential roles of TUSC3 in diagnosis and treatment of TUSC3‐related diseases, especially cancer.

Transcriptome using Illumina sequencing reveals the traits of spermatogenesis and developing testes in Eriocheir sinensis.

Chinese mitten crab (Eriocheir sinensis) has the spermatozoa with typical aflagellate, decondensed chromatin, cup-shaped nuclei, and radial arms. However, the mechanism of spermatogenesis during which the specific spermatozoa are generated in this species is yet unclear. Here, the transcriptome of developing testis in E. sinensis was analyzed using the ways of RNA-seq and bioinformatics analysis to identify candidate genes potentially involved in development of testis and spermatogenesis. The Illumina HiSeq2500 sequencing of three replicons of samples produced a total of 145.19 M clean reads representing with a total of 21.34 Gb bases and 45.48% GC content. 56.30% clean reads were mapped to the draft genome of E. sinensis. The assembly of the transcriptome yielded contigs of 5691802 sequences and unigenes of 406527 sequences. Total 24246 and 40793 transcripts were annotated using Swissprot and Nr database, respectively. There were 48213 (70.31%) and 7858 (46.25%) transcripts with identity of more than 99 matching to mature testis unigenes in the databases of Nr and EST, respectively. The analytic results of KOG, GO and KEGG showed wide potential molecular functions of transcripts in the developing testes. KEGG analysis of unigenes yielded total 9422 predicted genes. Those predicted genes were involved in total 216 KEGG pathways related to the physiological activities of developing testis. 1975 predicted genes were involved in cellular and subcellular structural alteration of male germ cells. There were important roles of some pathways in the processes of morphological and structural biogenesis pertaining to testis development and spermatogenesis. Other 583 unigenes encoding the genetic and epigenetic factors also be found, which might contribute to the decondensation and stability of decondensed nuclei in the spermatozoa. These predicted events provide a view of the potential molecular mechanisms of development of testis and spermatogenesis in E. sinensis.

Different expression of leptin and IGF1 in the adult and prepubertal testis in dogs

Leptin (Lep) and insulin-like growth factor 1 (IGF1) are implicated in the regulation of testicular function, but in dogs, our knowledge is limited to the possible role of the IGF1 system in testicular tumours. In this study, we aimed to describe and compare gene expression and protein localization of Lep, IGF1 and their receptors (LepR and IGF1R, respectively) in the testis of healthy adult and prepubertal dogs. Testes were collected from sexually healthy mature (n=7) and from 8-week-old dogs (n=7). Relative gene expression of Lep, LepR, IGF1 and IGF1R was determined by semi-quantitative real-time (TaqMan) PCR and cellular distribution in the testis by immunohistochemistry. Statistical analysis was carried out with Student's t test. Lep and LepR mRNA concentration was similar between the two groups, but IGF1 and IGF1R gene expression was significantly higher in the 8-week-old pups. Protein localization and the intensity of signals differed by age. In adults, Lep and LepR immunoreactivity was detected in spermatocytes and spermatids. Leydig cells showed sporadic, weak Lep staining. In prepubertal animals, intense Lep signals were present in Leydig and Sertoli cells, and LepR was found in Leydig cells. IGF1 and IGF1R protein was expressed in spermatogonia of the mature testis; IGF1 signals in Leydig cells seemed stronger than IGF1R. In the pups, IGF1 and IGF1R staining was detected in Leydig cells and in gonocytes. Sertoli cells showed weak IGF1 and sporadic, weak IGF1R signals. In conclusion, Lep and IGF1 may support spermatogenesis in adult dogs and mediate Leydig cell function. In the immature testis, they may promote development of Sertoli and Leydig cells and gonocytes.

Circannual testis and moult cycles persist under photoperiods that disrupt circadian activity and clock gene cycles in spotted munia.

We investigated whether circannual rhythms underlying annual testis maturation and moult cycles are independent of duration and frequency of the light period and circadian clock control in non-photoperiodic spotted munia. Birds were subjected to an aberrant light-dark (LD) cycle (3.5h L:3.5h D; T7, where T is the period length of the LD cycle) and continuous light (LL, 24h L:0h D), with controls on 12h L:12h D (T24, 24 h LD cycle). We measured the behavioural activity pattern of the birds and 24 h mRNA oscillations of circadian clock genes (bmal1, clock, per2, cry1, cry2) in the hypothalamus, the putative site of seasonal timing. Diurnal munia were rhythmic in behaviour with the period of the activity-rest cycle matched to T7 and T24, and became behaviourally arrhythmic with activity scattered throughout 24 h under LL. Similarly, exposure to 3.5h L:3.5h D and LL caused arrhythmicity in 24 h clock gene expression, suggesting disruption of internal circadian timing at the transcriptional level; a significant rhythm was found under 12h L:12h D. During an exposure of 80 weeks, munia showed two to three cycles of testis maturation and wing primaries moult under all photoperiods, although with a longer period under 12L:12D. Thus, the frequency of light period under 3.5h L:3.5h D or LL disrupted circadian clock gene cycles, but did not affect the generation of circannual testis and moult cycles. We conclude that the prevailing light environment and hypothalamic circadian gene cycles do not exert direct control on the timing of the annual reproductive cycle in spotted munia, suggesting independent generation of the circadian and circannual rhythms in seasonally breeding species.

Relationship Between Physico-Chemical Parameters and Reproductive Indices of Parachanna obscura (Gunther 1861) in Eleyele Reservoir, Ibadan, Nigeria

Propagation in fishes depends on the level of gonad maturation which could be influenced by environmental conditions. However, declining water quality due to environmental degradation has been identified as a hindrance to such ecosystem services in aquatic ecosystems. Therefore, size distribution and stages of gonad development of P. obscura in relation to physic-chemical parameters of Eleyele reservoir were studied. Samples of water and Parachanna obscura were collected monthly from five stratified sampling points and fishers catch, respectively for 24 months. Fish were grouped according to sizes (10-15.9, 16.0-19.9 and ≥ 20 cm), and gonads assessed for maturation. Relationship between reproductive indices and physic-chemical parameters were determined using Principal Component Analysis. The size-groups distributions were 10-15.9 cm (28.6%), 16.0-19.9 cm (38.7%) and ≥ 20 cm (32.7%). All the five maturation stages (I-V) were discerned in the female while only stages II-IV were observed in male samples. All the size groups showed strong associations with pH (β=0.346), ammonia (β=0.303) and temperature (β=0.161). Ovary development was significantly influenced by DO (β=0.827), TDS (β=0.777) and TS (β=0.813), while testes maturation was more influenced by temperature (β=0.626). This information will serve as guides for effective ecosystem management through the control of anthropogenic activities on this reservoir and similar water bodies to enhance resource conservation and/or sustainable management.

Histomorfometria gonadal comparada de Astyanax lacustris (Lütken, 1875) e Psellogrammus kennedyi (Eigenmann, 1903) (Characiformes, Characidae) em um reservatório no semiárido brasileiro

O objetivo deste estudo foi analisar comparativamente as principais caracterí­­sticas morfológicas e histomorfométricas de ovários e testí­­culos de Astyanax lacustris (Lütken, 1875) e Psellogrammus kennedyi (Eigenmann, 1903). Os peixes foram obtidos entre abril de 2014 e março de 2015, no Reservatório Monte Alegre (Salgueiro, Pernambuco). No total, 240 indiví­­duos foram observados macroscopicamente e, destes, 126 gônadas foram analisadas histologicamente. Durante o perí­­odo estudado, A. lacustris apresentou quatro diferentes estádios gonadais e P. kennedyi apresentou três. Para ambas as espécies, todos os meses foram detectados macroscopicamente, ovócitos vitelogênicos e, microscopicamente, ovócitos pré-vitelogênicos. O dií­¢metro dos ovócitos vitelogênicos foi maior (471,68 µm±160,55; p&lt;0,05) para fêmeas de A. lacustris. O dií­¢metro dos túbulos seminí­­feros (114,68 µm±34,57; p&lt;0,05) e a altura do epitélio germinativo (18,75 µm±5,47; p&lt;0,05) foram maiores para P. kennedyi. Os testí­­culos maduros em A. lacustris apresentaram epitélio germinativo com bordas melhor delimitadas, quando comparado a P. kennedyi. As observações macroscópicas demonstraram que os maiores valores do í­­ndice gonadossomático (IGS) de ambas as espécies coincidiu com o perí­­odo de maior precipitação (entre novembro/2014 e maio/2015) na região. Por fim, a partir das observações macro e microscópicas, concluiu-se que as duas espécies apresentam desova parcelada com desenvolvimento ovocitário assincrônico.&#x0D;