Synchronously sexual maturity in hermaphrodite fish as revealed by transcriptome analysis in Plectropomus leopardus

Leopard coral grouper (Plectropomus leopardus) is a type of hermaphrodite fish, but the mechanisms of gonadal development and gametogenesis remain unclear. In the present study, we performed histological observation and transcriptomic analysis during the process of sexual differentiation in P. leopardus. According to the histological results, sexual differentiation was completed at 15 months old, developed synchronously in male and female individuals at 2 years old, and matured synchronously at 3 years old. Comparative transcriptomic analyses showed that the gonadal had differentiated by 15 months old, with enrichment of pathways associated with cell proliferation, transcriptional metabolism, and germline stem cell differentiation. Furthermore, cilium movement and fatty acid anabolism, which are associated with spermatogenesis and oocyte growth, were significantly enriched at 3 years old. In addition, key genes associated with male and female sex differentiation, such as amh, dmrt1, dmrt2a, zp4, sox3, gdf9, and gsdf, were identified by weighted gene co-expression network analysis (WGCNA). Finally, the localization and expression of the key genes amh and sox3 were observed in different cell types within the testes and ovaries, reflecting the development of the testes and ovaries, respectively. All the evidence indicates that P. leopardus is a hermaphrodite and synchronously sexually mature fish. Our study complements the gonadal development patterns of hermaphroditic fish by providing new insights into the molecular mechanisms underlying sexual differentiation and sex change in hermaphroditic groupers.

Sex determination in papaya: Current status and perspectives

Papaya (Carica papaya L.) is an economically significant plant that produces fruit consumed worldwide due to its organoleptic characteristics. Since their commercial production, papaya fruits have faced several problems, such as pests, which have been partly resolved using transgenic varieties. Nevertheless, a principal challenge in this cultivation is the plant's sex determination. The sex issue in papaya is complex because papaya flowers can bear three sex forms: male, female, and hermaphrodite, which affects their fruit production, shape, and yield. Fruits from hermaphrodite plants are preferred more by consumers than female ones, and male plants rarely produce fruits without commercial value. Chromosomes are responsible for sex determination in papaya, denoted as XY for male, XX for female, and XYh for hermaphrodite. However, genes related to sex have been reported but are not conclusive. Factors such as the environment, hormones, and genetic and epigenetic background can also affect sex expression. Therefore, in this review, we will discuss recent research on the sex of papaya, from reported genes to date, their biology, and sexing approaches using molecular markers and their advantages.

Inheritance and molecular mapping of solitary/cluster fruit-bearing habit in Luffa

Fruiting behaviour and sex form are important goals for Luffa breeders and this study aimed to shed light upon inheritance patterns for both these traits. The hermaphrodite form of Luffa acutangula (known as Satputia) is an underutilized vegetable with a unique clustered fruiting habit. Its desirable traits, such as plant architecture, earliness, as well as contrasting traits like unique clustered fruiting, bisexual flower, and crossability with Luffa acutangula (monoecious ridge gourd with solitary fruits), make it a potential source for trait improvement and mapping of desirable traits in Luffa. In the present study, we have elucidated the inheritance pattern of fruiting behaviour in Luffa using F₂ mapping population generated from a cross between Pusa Nutan (Luffa acutangula, monoecious, solitary fruiting) × DSat-116 (Luffa acutangula, hermaphrodite, cluster fruiting). In F₂ generation, the observed distribution of plant phenotypes fitted in the expected ratio of 3:1 (solitary vs cluster) for fruit-bearing habit. This is the first report of monogenic recessive control for cluster fruit-bearing habit in Luffa. Herein, we designate for the first time the gene symbol cl for cluster fruit bearing in Luffa. Linkage analysis revealed that SRAP marker ME10 EM4-280 was linked to the fruiting trait at the distance of 4.6 cM from the Cl locus. In addition, the inheritance pattern of hermaphrodite sex form in Luffa was also studied in the F₂ population of Pusa Nutan × DSat-116 that segregated into 9:3:3:1 ratio (monoecious:andromonoecious:gynoecious:hermaphrodite), suggesting a digenic recessive control of hermaphrodite sex form in Luffa, which was further confirmed by the test cross. The inheritance and identification of molecular marker for cluster fruiting trait provides a basis for breeding in Luffa species.

Life history of the endemic Hawaiian hogfish Bodianus albotaeniatus: age, growth, and reproduction

Growth rate, longevity, maturity, and spawning seasonality were estimated for the endemic Hawaiian hogfish Bodianus albotaeniatus. The sex-specific von Bertalanffy growth parameters are L_∞ = 339 mm fork length (L_F ) and K = 0.66 year^-1 for females; L_∞ = 417 mm L_F and K = 0.33 year^-1 for males. The maximum age is 22 years. Histological gonad analysis and the absence of small and young males indicate a monandric protogynous hermaphrodite. Size and age at maturity for combined sexes are L₅₀ = 238 mm L_F and A₅₀ = 1.6 years. This article is protected by copyright. All rights reserved.

Characterization of 21 microsatellite loci for the precocious, grass-shrimp trematode Alloglossidium renale

We developed microsatellite markers to use in studying the population genetics of the trematode Alloglossidium renale, a fluke with a precocious life cycle where sexual maturation occurs in a grass shrimp. Among 21 tested loci in a Mississippi population sample, 14 were polymorphic, 12 of which significantly deviated from Hardy-Weinberg Equilibrium (HWE). We estimated identity disequilibrium (ID) to confirm whether the deviations from HWE were due to significant amounts of selfing or due to technical factors. The selfing rate derived from F_IS was 86.6%, whereas the selfing rate obtained by ID was 83.9%, indicating that the deviation in HWE was due to a high amount of selfing within the population. These markers will be useful for ecological and evolutionary studies of A. renale especially in relation to the interplay of hermaphroditic mating systems, inbreeding depression, and transmission dynamics.

Parasites and their impact on thick-shelled river mussels Unio crassus from two populations in Luxembourg

The thick-shelled river mussel Unio crassus Philipsson, 1788 is a species native to many European habitats, with declining populations. The impact of parasite communities on health status of this species is poorly understood. In this study, parasites of 30 U. crassus specimens from the Our and Sauer Rivers in Luxembourg were identified morphologically and, in some cases, using molecular genetic methods. The findings were correlated to selected parameters (total length, visceral weight, shell lesions, gonadal stage). The 2 populations did not differ in shell length, visceral weight, number of males and females, gonadal scoring, shell lesions, and the occurrence of glochidia. The prevalence and infestation intensities of detected Trichodina sp., Conchophthirus sp., and freshwater mite larvae did not differ between the 2 populations, whereas the prevalence and infestation intensities of mite eggs, nymphs, and adults were significantly higher in the Sauer River. Rhipidocotyle campanula and European bitterling Rhodeus amarus larvae were only present in the Sauer. Histopathology revealed the destruction of the gonads by R. campanula and tissue damage by the mites. The only significant correlation of the selected parameters was a positive correlation between R. amarus occurrence and total length as well as a negative correlation between R. amarus occurrence and gonadal stage. In the Sauer River, 2 mussels were found to be hermaphrodites.

Consequences of artificial light at night on behavior, reproduction, and development of Lymnaea stagnalis

Light is an important zeitgeber that regulates many behavioral and physiological processes in animals. These processes may become disturbed due to the changes in natural patterns of light and dark via the introduction of artificial light at night (ALAN). The present study was designed to determine the effect of possible consequences of ALAN on reproduction, hatching success, developmental success, growth rate, feeding rate, mortality rate, and locomotor activity of the simultaneous hermaphrodite pond snail Lymnaea stagnalis. Snails were exposed to different light intensities at night that simulate actual ALAN measurements from the snail's night environment. The data revealed that exposure to ALAN at a low level significantly affected the cumulative number of laid eggs. At the same time, snails exposed to ALAN laid smaller eggs than those laid under normal light-dark cycles. Additionally, high light-intensity of ALAN delayed development and hatching of eggs of L. stagnalis while it showed no effect on hatching percentage. Furthermore, ALAN increased both the feeding and growth rates but did not lead to mortality. The results also show that snails exposed to dark conditions at night travel longer distances and do so faster than those exposed to ALAN. In light of these findings, it is clear that ALAN may have an influence on snails and their abundance in an environment, possibly disturbing ecological stability.

Microsatellite DNA markers applicable to paternity inference in the androdioecious gooseneck barnacle Octolasmis warwickii (Lepadiformes: Poecilasmatidae)

The gooseneck barnacle Octolasmis warwickii has a rare sexual system called androdioecy, in which hermaphrodites and dwarf males co-occur. It has been hypothesized that dwarf males can coexist with conspecific hermaphrodites when dwarf males are capable of leaving more offspring than hermaphrodites via male reproduction. This hypothesis of reproductive superiority of dwarf males can be validated by comparing the reproductive success between dwarf males and hermaphrodites through DNA marker-based parentage testing. In the present study, we developed microsatellite DNA markers for O. warwickii, and evaluated the power of these markers to infer parentage based on simulation analysis. Using next generation sequencing, we obtained 344 microsatellite sequences suitable for designing primer sets for amplification in polymerase chain reaction (PCR). Of these, we examined the PCR amplification efficiency of 54 primer sets, of which 11 passed our primer screening in a population sample (n = 35). The developed markers exhibited moderate to high levels of polymorphisms, and met Hardy-Weinberg equilibrium with little evidence of significant allelic association to each other. Our simulated paternity inference suggested that the combinational use of the markers allows a high resolution of parentage (success rate of > 99.9%) if all candidate fathers are available.

Is the initiation of selfing linked to a hermaphrodite's female or male reproductive function?

ABSTRACT

There is an ongoing debate about whether simultaneous hermaphrodites capable of selfing should prefer selfing over outcrossing or vice versa. While many theoretical models predict a transmission advantage for alleles that favour selfing, empirical studies often reveal low selfing rates. Despite these considerations, the underlying mechanisms that determine reproductive strategies in simultaneously hermaphroditic animals are poorly understood. In our study on the facultatively selfing free-living flatworm, Macrostomum hystrix, we ask whether the initiation of selfing, as inferred from the differential spatial distribution of received sperm, is linked to an individual's female or male reproductive function. Specifically, the initiation of selfing could (i) be linked to the male function, when an individual is unable to donate sperm to others and hence donates sperm to self, or it could (ii) be linked to the female function, when an individual fails to receive sperm from others-and hence is unable to fertilize its eggs via outcrossing-thus inducing it to self-fertilize. We experimentally created a social environment that allowed focals to outcross via sperm donation, but simultaneously prevented them from receiving sperm-by pairing them with a partner lacking the male copulatory organ-so that fertilization of the focal's eggs was restricted to selfing. Our results suggest that such focals generally do not initiate selfing, while we readily observe selfing in isolated worms. This suggests that in isolated M. hystrix, it is the male function that is linked to the initiation of selfing, likely due to a lack of opportunities for sperm donation.

SIGNIFICANCE STATEMENT

A variety of simultaneously hermaphroditic animals are capable of reproducing via both selfing and outcrossing. While the reproductive choices of such animals can be modelled by the joint action of genetic (e.g. inbreeding depression) and ecological factors (e.g. partner availability), experimental evaluation of theoretical results is often lacking. By manipulating the social environment of focal individuals, we here provide evidence that explores the respective role that the co-occurring male and female sex functions have on the initiation of selfing in a simultaneously hermaphroditic flatworm species. Specifically, our results suggest that the initiation of selfing is linked to the worm's male function. Insights about which function is linked to the initiation of selfing may ultimately help to better understand reproductive decisions in simultaneous hermaphrodites.

Sex-changing patterns of Akoya pearl oyster (Pinctada fucata)

BACKGROUND

Pearl production by transplantation in Akoya pearl oyster (Pinctada fucata) is a biotechnology developed in Japan that skillfully utilizes the pearl-forming ability of oysters. In this method, cultured pearls are formed from a pearl nucleus and a small piece of mantle transplanted into the gonads of recipient pearl oysters. In this study, we hypothesized that the sex of the recipient pearl oyster might affect the quality of pearl produced. While some previous studies have examined the sex of Akoya pearl oyster, detailed information is lacking.

RESULTS

To investigate sex in Akoya pearl oyster, we collected small gonadal fragments from 1-year-old pearl oysters by biopsy. Using the collected gonad fragment, the sex of the oysters was determined by microscopic observation, and the remaining samples were stored for gene expression analyses. All oysters were labeled to distinguish each individual for serial samplings every four months over the 2-year study period. At the start of experiment, nearly all of the pearl oysters were male, but the male:female ratio ofmale decreased over the course of the experiment. Interestingly, the number of males increased after spring, during the breeding season. This suggests that, in pearl oyster, sex is affected by season. Expression analysis of sex-related genes (Dmrt2, Vtg, Zp) indicated that all genes were expressed in all individuals and all periods.

CONCLUSIONS

These results suggest that Akoya pearl oysters are hermaphroditic, and that females appear as necessary, such as during the breeding season. These findings could contribute to higher efficiency and quality of pearl cultivation.

The ctenophore Mnemiopsis leidyi regulates egg production via conspecific communication

Background

Communication between individuals of the same species is an important aspect of mating and reproduction in most animals. In simultaneously hermaphroditic species with the ability to self-fertilize, communication with conspecifics can be essential to avoid inbreeding depression. One such behavioral adaptation observed in some simultaneous hermaphrodites is gamete trading. This behavior involves individual hermaphrodites in pairs alternating between reproducing as the male and female, and, as such, necessarily requires communication and coordination between mates. Little is known about communication in ctenophores and conspecific communication has not been described in this group; however, our previous work suggested that the ctenophore Mnemiopsis leidyi might engage in gamete trading. We tested for this possibility by constructing divided arenas (both sealed and permeable) that allowed us to measure individual egg output for paired M. leidyi.

Results

We found that, when not allowed to interact, size-matched individuals produced similar numbers of eggs on each side of the arena. However, if allowed to interact and exchange water, size-matched pairs produce significantly different numbers of eggs on each side of the arena, suggesting that these pairs use chemical communication to modulate reproduction in the presence of conspecifics as would be expected in gamete trading.

Conclusion

This finding presents exciting new possibilities for future investigations into the nature of signaling in M. leidyi. Furthermore, this first evidence of conspecific communication in Ctenophora, a group that branched off from the rest of animals more than 600 million years ago, has significant implications for the signaling ability of the last common ancestor of all animals.

Electronic supplementary material

The online version of this article (10.1186/s12898-018-0169-9) contains supplementary material, which is available to authorized users.

Restricted female function of hermaphrodites in a gynodioecious shrub, Daphne jezoensis (Thymelaeaceae)

Gynodioecy is the coexistence of hermaphrodites and females in a population. It is supposed to be an intermediate stage in the evolutionary pathway from hermaphroditism to dioecy in angiosperm. Hermaphrodites gain fitness through both seed and pollen production whereas females gain fitness only through seed production. As females spread in a gynodioecious population, sexual selection prompts hermaphrodites to invest in male function and male-biased hermaphrodites prevail. In the gynodioecious shrub Daphne jezoensis (Thymelaeaceae), female frequency is stably around 50% in most populations, and fruit-set rate of hermaphrodites is commonly low. Therefore, D. jezoensis is likely at a later stage in the evolutionary pathway. Female function of hermaphrodites (fruit-set rate, selfing rate, seed size, and germination rate) was assessed in three populations under natural conditions. In order to evaluate the potential seed fertility and inbreeding depression by selfing in hermaphrodites, hand pollination treatments were also performed. Over a 2-year period under natural conditions, 18-29% of hermaphrodites and 69-81% of females set fruit. Across all three populations, the mean fruit-set rate ranged 9.5-49.2% in females and only 3.9-10.2% in hermaphrodites. Even with artificial outcross-pollination, 59-91% of hermaphrodites failed to set any fruit. When self-pollination was performed in hermaphrodites, both of fruit-set and germination rates were decreased, indicating early-acting inbreeding depression. In addition, more than half of the hermaphrodite seeds were produced by selfing under natural pollination, but pollinator service was still required. Totally, hermaphrodites performed poorly as seed producers because of the intrinsically-low fruiting ability and a combination of autogamous selfing and strong inbreeding depression, indicating the absence of reproductive assurance. These results indicate that the mating system of D. jezoensis is functionally close to dioecy.

Germ cell cysts and simultaneous sperm and oocyte production in a hermaphroditic nematode

Studies of gamete development in the self-fertile hermaphrodites of Caenorhabditis elegans have significantly contributed to our understanding of fundamental developmental mechanisms. However, evolutionary transitions from outcrossing males and females to self-fertile hermaphrodites have convergently evolved within multiple nematode sub-lineages, and whether the C. elegans pattern of self-fertile hermaphroditism and gamete development is representative remains largely unexplored. Here we describe a pattern of sperm production in the trioecious (male/female/hermaphrodite) nematode Rhabditis sp. SB347 (recently named Auanema rhodensis) that differs from C. elegans in two striking ways. First, while C. elegans hermaphrodites make a one-time switch from sperm to oocyte production, R. sp. SB347 hermaphrodites continuously produce both sperm and oocytes. Secondly, while C. elegans germ cell proliferation is limited to germline stem cells (GSCs), sperm production in R. sp. SB347 includes an additional population of mitotically dividing cells that are a developmental intermediate between GSCs and fully differentiated spermatocytes. These cells are present in males and hermaphrodites but not females, and exhibit key characteristics of spermatogonia - the mitotic progenitors of spermatocytes in flies and vertebrates. Specifically, they exist outside the stem cell niche, increase germ cell numbers by transit-amplifying divisions, and synchronously proliferate within germ cell cysts. We also discovered spermatogonia in other trioecious Rhabditis species, but not in the male/female species Rhabditis axei or the more distant hermaphroditic Oscheius tipulae. The discovery of simultaneous hermaphroditism and spermatogonia in a lab-cultivatable nematode suggests R. sp. SB347 as a richly informative species for comparative studies of gametogenesis.

Seasonal expression of arginine vasotocin mRNA and its correlations to gonadal steroidogenic enzymes and sexually dimorphic coloration during sex reversal in the gilthead seabream (Sparus aurata)

Arginine vasotocin is a hormone produced in the hypothalamus of teleost fish that has been shown to regulate gonad development and sexual behavior. To study the role of arginine vasotocin in the gonadal cycle of the hermaphrodite gilthead seabream, Sparus aurata, we cloned the seabream arginine vasotocin (avt) complementary DNA (cDNA). We investigated the expression of brain avt throughout the gonad cycle using real-time quantitative PCR and compared its expression levels to the expression levels of two key gonadal steroidogenic enzymes, cyp19a1a and cyp11b2. In July, when the process of sex reversal is thought to begin, avt expression was elevated over the previous 2 months. Avt in the brain remained at or above the level of July until November then peaked again in December. There was no difference between males and females in the expression levels of brain avt throughout the year. However, only in ambisexual fish was the expression of the cyp19a1a gonadal aromatase correlated to the expression of avt in the brain. Cyp11b2 did not show any correlation to brain avt expression. We also found that females had more intense body coloration than males and that this intensity peaked prior to spawning. Avt expression and female coloration were positively correlated. The fact that brain avt expression was lowest during gonad quiescence, together with the observation of a correlation between brain avt with gonadal cyp19a1a and body coloration during that time suggests that avt may play a role during the process of sex reversal and spawning of the gilthead seabream.

Factors affecting egg production in the selfing mangrove rivulus (Kryptolebias marmoratus)

The mangrove rivulus, Kryptolebias marmoratus, is one of two known vertebrate species with preferentially self-fertilizing hermaphrodites. Males also exist, and can outcross with hermaphrodites. Outcrossing events vary across wild populations and occur infrequently in laboratory settings. This study sought to add dimension to our understanding of mangrove rivulus reproductive habits by probing the effects of male presence on hermaphroditic unfertilized egg production. Specifically, we quantified egg production of solitary hermaphrodites compared to hermaphrodites exposed to males and exposed to other hermaphrodites. Hermaphrodites tended to produce more fertilized eggs in the presence of males but unfertilized eggs were produced relatively rarely and did not vary significantly among treatments. The probability that hermaphrodites would produce eggs changed as a function of genetic dissimilarity with their partner and in a season-dependent manner. In the fall, the probability of laying eggs decreased as a function of increased genetic dissimilarity, regardless of the sex of the partner. In the winter/spring, however, the probability of laying eggs increased markedly with increased genetic dissimilarity, regardless of the sex of the partner. Our findings indicate that reproductive decisions are modulated by factors beyond male presence, and we discuss a number of alternative hypotheses that should be tested in future studies.

Spermatozeugmata structure and dissociation of the Australian flat oyster Ostera angasi: Implications for reproductive strategy

Variation in reproductive strategy is one of the key factors contributing to recruitment success of molluscs in different habitats. Spermcasting is a unique mode in mollusc reproduction where males produce spermatozeugmata, a radially arrayed sperm cluster wrapped by gelatinous membrane. In this study, spermatozeugmata structure and their dissociation in the Australian flat oyster Ostrea angasi were investigated to elucidate the reproductive strategy in spermcasting molluscs. The histological observation indicated that spermatogonia gradually aggregated in the gonad follicle at the early gonad development stages and developed into spermatozeugmata and became tightly packed at the advanced stages. Even though mature male and female gametes could be found in a hermaphroditic individual, the animal may prevent self-fertilization by shedding different sex gametes at different time. The O. angasi sperm are similar in size and shape to broadcasting oysters, but have one additional mitochondrion. Variations in maintaining spermatozeugmata integrity and sperm motility between individuals depended on the level of masculinity or femineity. The durations of spermatozeugmata dissociation and sperm viability were longer in males than in hermaphrodites. The unique structure and capability for spermatozeugmata to maintain the functional integrity after spawning have adaptive significance for fertilization and gamete dispersal in this species.

The sex lives of ctenophores: the influence of light, body size, and self-fertilization on the reproductive output of the sea walnut, Mnemiopsis leidyi

Ctenophores (comb jellies) are emerging as important animals for investigating fundamental questions across numerous branches of biology (e.g., evodevo, neuroscience and biogeography). A few ctenophore species including, most notably, Mnemiopsis leidyi, are considered as invasive species, adding to the significance of studying ctenophore ecology. Despite the growing interest in ctenophore biology, relatively little is known about their reproduction. Like most ctenophores, M. leidyi is a simultaneous hermaphrodite capable of self-fertilization. In this study, we assess the influence of light on spawning, the effect of body size on spawning likelihood and reproductive output, and the cost of self-fertilization on egg viability in M. leidyi. Our results suggest that M. leidyi spawning is more strongly influenced by circadian rhythms than specific light cues and that body size significantly impacts spawning and reproductive output. Mnemiopsis leidyi adults that spawned alone produced a lower percentage of viable embryos versus those that spawned in pairs, suggesting that self-fertilization may be costly in this species. These results provide insight into the reproductive ecology of M. leidyi and provide a fundamental resource for researchers working with them in the laboratory.

Management of a 3-year-old child with ambiguous genitalia

True hermaphrodites have characteristics tissue both sex in the form of presence of vagina uterus, fallopian tubes and ovaries as in female and presence of testis seminiferous tubules but penis as in penoscrotal hypospadias and bifid scrotal sac confuses as well developed labia majora. Determination of sex as per parents view in our social set up. The case was provisionally diagnosed as intersex. Total abdominal hysterectomy, bilateral salphingo-oophorectomy and colpectomy were conducted. A 3-year-old child referred by a pediatrician to Nalanda Medical College, child surgical department for investigation and management of his ambiguous genitalia having following features like, urine was not passing from the tip of penis; penis along with apparently looking female genitalia was taken under treatment. Examination under general anesthesia showed a presence of both male/female internal genitalia and gonads with features of external genitalia of both sexes. After total abdominal hysterectomy and human chorionic gonadotrophin treatment growth of phallus and testicle was noted. The child was made male after extirpation of female genitals. This case illustrates that gender correction can be made as per patients consent in adult but at this stage social customs and parents consent dictated the treatment.

Reproductive investment, synchrony and recruitment success in marine broadcast spawners: Effects of mating system and habitat (exposed shore versus estuary)

The timing and synchrony of gamete release in broadcast spawners have important implications for fertilization success, recruitment and to explain differences in reproductive success under distinct reproductive modes in sympatry. Our objective was to compare the reproductive timing and investment for sister species with contrasting mating systems; Fucus guiryi (selfing hermaphroditic) and Fucus vesiculosus (dioecious) in habitats with different wave exposures (exposed shore and estuary). Over two months, daily gamete release, recruitment and population structure were recorded. Our results show spawning synchrony between species and habitats, but release events in hermaphrodites occupied broader temporal windows in estuarine than exposed shore habitats. On the exposed shore both species increased the synchrony of release and amount of eggs. In the estuary, hermaphrodites relied on broader temporal spawning windows and a larger canopy, and the dioecious species had higher recruitment success, important factors determining persistence.

Recent advances and perspectives in molecular epidemiology of Taenia solium cysticercosis

Cysticercosis caused by accidental ingestion of eggs of Taenia solium is spreading all over the world through globalization and is one of the most neglected, neglected tropical diseases (NTDs) or neglected zoonotic diseases (NZDs). In the present study, the reason why T. solium cysticercosis has been neglected is discussed at first, and followed with an overview on the most recent advances and perspectives in molecular approaches for epidemiology of T. solium taeniasis/cysticercosis, since although taeniasis does not constitute recognized zoonoses, transmission and complete development are dependent on human definitive hosts. Main topics are discussions on (1) the two, Asian and Afro/American, genotypes of T. solium, (2) comparative analysis of mitochondrial (haploid) and nuclear (diploid) genes, and (3) the presence of hybrids of these two genotypes which indicates out-crossing of two genotypes in hermaphrodite tapeworms in Madagascar. Additional topics are on (4) the usefulness of phylogeographic analyses to discuss where the infection was acquired from, and (5) miscellaneous unsolved topics around these genetic diversity of T. solium.

Molecular identification of sex in Simarouba glauca by RAPD markers for crop improvement strategies

Due to lack of morphological methods to identify sex at early stage in the plants with long juvenile period the application of molecular markers is expected to facilitate breeding program. The objective of this study is to identify molecular markers linked to sex determination of the plant Simarouba glauca which assists in crop improvement program. Random amplified polymorphic DNA primers were tested on dioeceious and hermaphrodite plant Simarouba glauca. A set of eighty five RAPD primers were screened out of which only five primers were found to be associated with sex. The primer OPU-10 is male specific and OPD-19 primer is female specific. Another primer OPU-19 produced a unique amplification in only hermaphrodite individuals. Female and hermaphrodite specific primer OPS-05 amplified an amplicon in female and hermaphrodite and was absent in male plant. Primer OPW-03 produced amplicon specific to male and hermaphrodite plants and was absent in female plants.

The link between immunity and life history traits in scleractinian corals

Immunity is an important biological trait that influences the survival of individuals and the fitness of a species. Immune defenses are costly and likely compete for energy with other life-history traits, such as reproduction and growth, affecting the overall fitness of a species. Competition among these traits in scleractinian corals could influence the dynamics and structural integrity of coral reef communities. Due to variability in biological traits within populations and across species, it is likely that coral colonies within population/species adjust their immune system to the available resources. In corals, the innate immune system is composed of various pathways. The immune system components can be assessed in the absence (constitutive levels) and/or presence of stressors/pathogens (immune response). Comparisons of the constitutive levels of three immune pathways (melanin synthesis, antioxidant and antimicrobial) of closely related species of Scleractinian corals allowed to determine the link between immunity and reproduction and colony growth. First, we explored differences in constitutive immunity among closely related coral species of the genus Meandrina with different reproductive patterns (gonochoric vs. hermaphrodite). We then compared fast-growing branching vs. slow-growing massive Porites to test co-variation between constitutive immunity and growth rates and morphology in corals. Results indicate that there seems to be a relationship between constitutive immunity and sexual pattern with gonochoric species showing significantly higher levels of immunity than hermaphrodites. Therefore, gonochoric species maybe better suited to resist infections and overcome stressors. Constitutive immunity varied in relation with growth rates and colony morphology, but each species showed contrasting trends within the studied immune pathways. Fast-growing branching species appear to invest more in relatively low cost pathways of the immune system than slow-growing massive species. In corals, energetic investments in life-history traits such as reproduction and growth rate (higher energy investment) seem to have a significant impact on their capacity to respond to stressors, including infectious diseases and coral bleaching. These differences in energy investment are critical in the light of the recent environmental challenges linked to global climate change affecting these organisms. Understanding physiological trade-offs, especially those involving the immune system, will improve our understanding as to how corals could/will respond and survive in future adverse environmental conditions associated with climate change.