Hermaphrodite Forms Research Articles

Absence of the Candidate Male Sex-Determining Gene dmrt1b(Y) of Medaka from Other Fish Species

Although the sex-determining genes are known in mammals, Drosophila, and C. elegans, little is known in other animals. Fishes are an attractive group of organisms for studying the evolution of sex determination because they show an amazing variety of mechanisms, ranging from environmental sex determination and different forms of hermaphroditism to classical sex chromosomal XX/XY or WZ/ZZ systems and modifications thereof. In the fish medaka, dmrt1b(Y) has recently been found [1, 2] to be the candidate male sex-determining gene. It is a duplicate of the autosomal dmrt1a gene, a gene acting in the sex determination/differentiation cascade of flies, worms, and mammals. Because in birds dmrt1 is located on the Z-chromosome [3], both findings led to the suggestion that dmrt1b(Y) is a “non-mammalian Sry” with an even more widespread distribution. However, although Sry was found to be the male sex-determining gene in the mouse and some other mammalian species, in some it is absent [4] and has obviously been replaced by other genes that now fulfil the same function. We have asked if the same might be true of the dmrt1b(Y) gene. We find that the gene duplication generating dmrt1b(Y) occurred recently during the evolution of the genus Oryzias. The gene is absent from all other fish species studied. Therefore, it may not be the male-sex determining gene in all fishes.

Sex determination in the androdioecious plant Datisca glomerata and its dioecious sister species D. cannabina.

Datisca glomerata is an androdioecious plant species containing male and hermaphroditic individuals. Molecular markers and crossing data suggest that, in both D. glomerata and its dioecious sister species D. cannabina, sex is determined by a single nuclear locus, at which maleness is dominant. Supporting this conclusion, an amplified fragment length polymorphism (AFLP) is heterozygous in males and homozygous recessive in hermaphrodites in three populations of the androdioecious species. Additionally, hermaphrodite x male crosses produced 1:1 sex ratios, while hermaphrodite x hermaphrodite crosses produced almost entirely hermaphroditic offspring. No perfectly sex-linked marker was found in the dioecious species, but all markers associated with sex mapped to a single linkage group and were heterozygous in the male parent. There was no sex-ratio heterogeneity among crosses within D. cannabina collections, but males from one collection produced highly biased sex ratios (94% females), suggesting that there may be sex-linked meiotic drive or a cytoplasmic sex-ratio factor. Interspecific crosses produced only male and female offspring, but no hermaphrodites, suggesting that hermaphroditism is recessive to femaleness. This comparative approach suggests that the hermaphrodite form arose in a dioecious population from a recessive mutation that allowed females to produce pollen.

Setting budgets for general practice in the new NHS

<h3>Abstract</h3> Sexual systems are highly diverse and have profound consequences for population dynamics and resilience. Yet, little is known about how they evolved. Using phylogenetic Bayesian modelling and a sample...

Neuropeptide Y (NPY) induces gonad reversal in the protogynous bluehead wrasse,Thalassoma bifasciatum (Teleostei: Labridae)

Female-to-male sex transformation in the protogynous marine fish Thalassoma bifasciatum is the culmination of a neuroendocrine cascade triggered by social and behavioral cues. We have previously shown that the hypothalamus and pituitary gland, key components of the neuroendocrine axis, play a significant role in gender reversal of this species. However, nothing is known about the possible involvement of other brain factors with the hypothalamo-pituitary gland axis in this fish. One such factor, neuropeptide Y (NPY) has been shown to effect a direct or indirect control of GtH-II release in gonochoristic teleosts. In view of this finding, we have investigated the role of NPY on sex reversal in T. bifasciatum. Females (n = 38) were injected intraperitoneally thrice weekly with NPY at a dose of 0.02 microgram/gbw dissolved in 0.6% saline. Controls (n = 48) received equal volumes of saline. Fish were sacrificed at 1, 4, 6, and 8 weeks. By the end of 8 weeks, 81.6% of the NPY-treated fish showed signs of gonad reversal ranging from early (n = 25) to mid- (n = 3) and late stage (n = 3). Furthermore, the effects of NPY appeared to be dependent on duration of treatment. At 6 and 8 weeks, the ovaries of four and three fish, respectively, were markedly degenerated. Our findings shed new light on the neuroendocrine control of sex reversal in T. bifasciatum and in hermaphroditic forms in general.

Aspectos anatômicos e funcionais do aparelho reprodutor de Parastacus brasiliensis (von Martens) (Crustacea, Decapoda, Parastacidae)

The absence of morphological external characteristics that allow the recognition of the sex as well as the presence of both male and female gonopores in the same animal [except in some sexual forms of Parastacus nicoleti (Philippi, 1882)] gives rise to the hypothetical existence of some form of hermaphroditism in crayfishes belonging to the genus Parastacus Huxley, 1879. Specimens of Parastacus brasiliensis (von Martens, 1869) were collected in a rivulet at Mariana Pimentel municipality, Rio Grande do Sul, Brazil. In the laboratory they were reared and dissected. The results suggest that P. brasiliensis may be a sequential hermaphroditic species, but male and female gonadal tissues were not simultaneously present in the analized samples. In testes and ovaries two pairs of genital ducts are present; that connect, respectively, to the gonopores on the coxae of the fifth and the third pairs of pereiopods. In the females only the apertures and anterior ducts seem to be functional, while in the males only the apertures and posterior ducts may be functional. The existence of different degrees of obstruction in the female genital apertures and different degrees of projection in the male genital apertures was observed. The aspect of the gonopores were used to recognize, externally, the sex of animais.

Role of ICE-proteases in apoptosis.

Apoptosis, or programmed cell death (PCD), is a naturally occurring process of cell suicide that plays a critical role in the development and maintenance of multicellular organisms. It is required for sculpting tissue architecture, for the development of the nervous and immune systems, as a defense against viral pathogens and protection from cancer1–11. Apoptosis is characterized by cellular shrinkage, nuclear condensation, membrane blebbing and fragmentation of the cell into membrane-enclosed vesicles called apoptotic bodies. The apoptotic bodies are rapidly phagocytosed by neighboring cells and macrophages without the release of cytoplasmic contents. This avoids inflammation and autoimmunization with intracellular constituents. Despite the biological importance of apoptosis, its molecular and biochemical basis remains obscure. The most important information about components of the death pathway comes from the study of the nematode worm Caenorhabditis elegans 12–14. The complete cellular lineage of the hermaphrodite form of C. elegans has been established. Of the 1,090 cells generated during development, 131 die by a cell-intrinsic death program. Genetic analysis has identified 14 genes that function in different steps of PCD in C. elegans. Two genes, ced-3 and ced-4, are required for these developmental deaths. If either is inactivated, none of the 131 cells die7. The ced-9 gene antagonizes the function of ced-3 and ced-4 by protecting cells from death7. In ced-9 loss-of-function mutants, cells that normally live undergo PCD early in development, resulting in embryonic lethality. Thus, ced-9 is necessary for the survival of most cells and presumably ced-9 accomplishes this by suppressing the cell death program7. Several recent discoveries have shed light on the function of the C. elegans cell-death genes and, more importantly, have shown that they have mammalian counterparts with similar functions. The machinery controlling cell viability and cell death appears to be highly conserved through evolution and is briefly reviewed below.KeywordsProgramme Cell DeathCysteine ProteasePARP CleavageCell Death MachineryNematode Worm Caenorhabditis ElegansThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Sexual development and sexuality in the Nassau grouper

Hermaphroditic sexual patterns are widespread among teleosts and are especially characteristic of certain perciform families. Among the most diverse groups of hermaphroditic species are the groupers, hamlets and sea basses of the family Serranidae. Like other groupers, the epinepheline serranid, Epinephelus striatus, the Nassau grouper, has long been assumed to exhibit monandric protogyny (a form of hermaphroditism in which all males derive from adult females by sex change). Histological and demographic data, however, indicate that the sexual pattern of this species is not monandric, and that, unlike other group species, the juveniles pass through a bisexual stage of gonadal development. Sexuality in the Nassau grouper is essentially gonochoristic, with potential for sex change. The combination of bisexuality and gonochorism is previously undescribed in the serranids.

Sexual development and sexuality in the Nassau grouper

Hermaphroditic sexual patterns are widespread among teleosts and are especially characteristic of certain perciform families. Among the most diverse groups of hermaphroditic species are the groupers, hamlets and sea basses of the family Serranidae. Like other groupers, the epinepheline serranid, Epinephelus striatus, the Nassau grouper, has long been assumed to exhibit monandric protogyny (a form of hermaphroditism in which all males derive from adult females by sex change). Histological and demographic data, however, indicate that the sexual pattern of this species is not monandric, and that, unlike other group species, the juveniles pass through a bisexual stage of gonadal development. Sexuality in the Nassau grouper is essentially gonochoristic, with potential for sex change. The combination of bisexuality and gonochorism is previously undescribed in the serranids.

Dioecious Solanum species of hermaphroditic origin is an example of a broad convergence

Unlike the taxa in some genera which show a range of variability in floral morphology, species of Solanum deviate very little from the typical hermaphroditic flower. The known deviant taxa fall into two classes: most are andromonoecious (male and hermaphroditic flowers on the same plant), and the remaining few are androdioedous (male flowers on one plant, hermaphroditic flowers on another)1.I report here evidence for the first instance of a truly dioecious species of Solanum, a significant discovery in the light of the floral uniformity of this large (second only to Senecio) and economically important genus. The most closely related species and species groups comprise only hermaphroditic forms; this dioecious species is among the few non-hermaphroditic forms native to the New World, the area of greatest species diversity of the genus. Furthermore, as shown below, the species is characterised by a functionally, though not morphologically, dioecious condition. Finally, this demonstration that the two floral forms represent different sexes of the same species, rather than (as originally described) different species, impels closer analysis of other species pairs.

Dopaminergic neurons in the nematode Caenorhabditis elegans

Dopamine is the putative transmitter of eight neurons in the hermaphrodite form of the nematode Caenorhabditis elegans. These include the cephalic and deirid neurons, which are believed to be mechanosensory. The male has an additional six dopaminergic neurons in the tail. Mutants have been selected which have defects in the formaldehyde induced fluorescence and lack dopamine to varying degrees, but they are not insensitive to touch. The dopaminergic neurons of C. elegans are compared with the homologous neurons in Ascaris lumbricoides.

Gynodiœcy in New Zealand Gentiana

THE observations of Burrows and Hobbs (preceding communication) direct attention again to one of the peculiarities of the New Zealand flora. As far back as 1880, Thomson1 had observed that “species, genera and families which are characterized by hermaphrodite flowers in other parts are frequently unisexual here”. Later work has brought to light a number of examples of gynodiœcy and other sex forms in New Zealand plants that were unknown to Thomson. In December 1961 I noted another in Ranunculus, a genus in which gynodiœcism had not hitherto been reported. A large colony of R. limosella F. Muell. ex Kirk consisting of many thousands of plants occupying several acres of the dried-up bed of Lake Forsyth on the Banks Peninsula was inspected and a pad of the lake mud was removed to observe the plants in detail. Some of the flowers in this sample were without stamens, and observations over the next few days on freshly opened flowers established that some purely female plants were present with the normal hermaphrodite form. A week later, the site was revisited with Dr. E. J. Godley and a search was made for female plants. None was found until the site of the original sample was rediscovered. At this point there was a small colony of female plants. It is evident that the proportion of female plants in the Lake Forsyth population as a whole was extremely small. A search for female plants in other localities established their presence over a wide area in Canterbury so that gynodiœcism appears to be a normal feature of this species.

Studies in the genusFucusL. I.Fucus distichusL. emend. Powell

The taxonomic status and nomenclature of the hermaphrodite forms of Fucus (other than the alga currently known asF. spiralisL. and certain hybrid forms) usually included under the nameFucus inflatusL. by European authors, but under several specific names by N. American and some other authors, is discussed. It is considered that the numerous forms described are best interpreted for the present as forms of a single, extremely plastic and widely distributed species.

Inheritance of Sex Forms in Luffa Acutangula Roxb.

SEX habit in plants is known to be controlled by genetic factors, although subject to environmental iluctuations. Poole and Grimball1, working on the inheritance of certain new sex forms in Cucumis melo, a member of the Cucurbitacese, have reported that the hermaphrodite form is genetically a double recessive to monoecious, and in F2 populations from crosses between them the following phenotypic ratio was obtained—9 monoecious : 3 andromoncecious : 3 gynomoncecious : 1 hermaphrodite. The gynomoncecious type was, however, susceptible to environmental fluctuation, giving rise occasionally to gynoecious and trimoncecious forms. On the basis of these results they have designated the several sex forms in their material as follows : monoecious (AG), andromoncecious (aG), gynomonoecious (Ag) and hermaphrodite (ag).

A case of a trumpet form of hermaphroditism

Abstracts. Surgery and X-ray therapy. A case of the trumpet form of hermaphroditism. Waiawelski (Zentr. F. Chir., 1930, no. 28) describes a case where, during an operation for a left-sided inguinal scrotal hernia, a body resembling a uterus was found in a hernial sac, the size of a goose egg. From the base of this body on both sides stretched for 10 s. rods (pipes) ending in fimbri-like formations. Below, in the abdominal fold, there were testicles with appendages. In Doug las'e, Plexus pampiniformis is found on both sides.

Parastrongyloides winchesi gen. et sp. nov. A Remarkable New Nematode Parasite of the Mole and the Shrew

The species of the Nematode genus Strongyloides are of considerable interest to helminthologists and extensive studies on the biology of their life-history have been carried out by various workers. Their chief interest lies in the fact that the parasitic stage consists of hermaphroditic forms only, while in the free-living stage there may be a differentiation into males and females before reaching the infective stage. This alternation in the life-cycle is also exhibited by the allied genus Rhabdias, with the exception that, according to Railliet (1899) and Goodey (1922), certain species from the snake do not appear to have this differentiation in the free-living stage.

The Anatomy and Life-History of the Nematode Rhabdias fuscovenosa (Railliet) from the Grass Snake Tropidonotus natrix

The members of the nematode genus Rhabdias present many features of great interest to the parasitologist. They are usually found inhabiting the lungs of amphibians and reptiles where their eggs or larvæ are produced. They have the general appearance of females and are either hermaphroditic or parthenogenetic in function (vide Goldschmidt, 1923, p. 176, on “Unisexual Monœcism”). Seurat (1920), p. 121, considers that the parasitic forms of R. dujardini and R. entomelas from the Slow worm Anguis fragilis are parthenogenetic females and not protandrous hermaphrodites because they lay an enormous number of eggs, whereas the hermaphroditic forms produce comparatively few eggs. Moreover, in R. entomelas he has been unable to find either receptacula seminis or spermatozoa.

Intersexes in Plantago lanceolata

Previous articleNext article FreeIntersexes in Plantago lanceolataA. B. StoutA. B. Stout Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 68, Number 2Aug., 1919 Article DOIhttps://doi.org/10.1086/332539 Views: 153Total views on this site Citations: 10Citations are reported from Crossref Journal History This article was published in the Botanical Gazette (1876-1991), which is continued by International Journal of Plant Sciences (1992-present). PDF download Crossref reports the following articles citing this article:HELENA KORPELAINEN Labile sex expression in plants, Biological Reviews 73, no.22 (Jan 2007): 157–180.https://doi.org/10.1111/j.1469-185X.1997.tb00028.xDavid G. Lloyd, K. S. Bawa Modification of the Gender of Seed Plants in Varying Conditions, (Jan 1984): 255–338.https://doi.org/10.1007/978-1-4615-6974-9_6J M M van Damme, W van Delden Gynodioecy in Plantago lanceolata L I. polymorphism for plasmon type, Heredity 49, no.33 (Dec 1982): 303–318.https://doi.org/10.1038/hdy.1982.104M. D. Ross DIGENIC INHERITANCE OF MALE STERILITY IN PLANTAGO LANCEOLATA, Canadian Journal of Genetics and Cytology 11, no.33 (Sep 1969): 739–744.https://doi.org/10.1139/g69-086Klaus Napp-Zinn Modifikative Geschlechtsbestimmung bei Spermatophyten, (Jan 1967): 153–213.https://doi.org/10.1007/978-3-642-95000-1_8E. N. Bressman INHERITANCE OF SEX IN CERTAIN SEED PLANTS, American Journal of Botany 21, no.66 (Jun 1934): 328–349.https://doi.org/10.1002/j.1537-2197.1934.tb04966.xA. B. Stout, Torasaburo Susa CHROMOSOME IRREGULARITIES IN RELATION TO STERILITY IN HEMEROCALLIS FULVA CLON EUROPA, Annals of the New York Academy of Sciences 31, no.11 (Dec 1929): 1–30.https://doi.org/10.1111/j.1749-6632.1929.tb55190.xJ. W. HESLOP HARRISON Sex in the Salicaceæ: and its Modification by Eriophyid Mites and other Influences, Journal of Experimental Biology 1, no.44 (Jul 1924): 445–472.https://doi.org/10.1242/jeb.1.4.445A. B. Stout Further experimental studies on self-incompatibility in hermaphrodite plants, Journal of Genetics 9, no.22 (Jan 1920): 85–129.https://doi.org/10.1007/BF02983271Chas. A. Shull Anthocyanin, Botanical Gazette 68, no.66 (Oct 2015): 484–485.https://doi.org/10.1086/332595

Sexless Twins or Free-Martins: A Common form of Hermaphroditism in the Bovine Species

Sexless Twins or Free-Martins: A Common form of Hermaphroditism in the Bovine Species

Studies in the Experimental Analysis of Sex

ABSTRACT The re-discovery of Mendel’s observations on heredity, and the extended application of his ideas by such writers as Correns, Tschermak, and Bateson to every branch of life, has had a very profound influence on contemporary biological conceptions, and it is not surprising that the problem of sex, which has occasioned so many speculative theories in past times, has been brought under the focus of Mendelian research and subjected to its analysis. The conceptions of segregation, of allelomorphism, of heterozygotism, to employ the accepted terminology of Professor Bateson (1), seem admirably suited in their application to the phenomena of sex, because in sexual reproduction we actually see that the sexual characters do segregate into two sharply separated sets of individuals, the males and the females, as if maleness and femaleness were in some way allelomorphic to one another, while the occurrence of hermaphrodite forms and the latent presence in one sex of characters proper to the opposite sex indicate the phenomenon of heterozygotism or sex-hybridism.

XXXII.—A Specimen of Helix pomatia with Paired Male Organs

Summary1. An account is given of a fully grown specimen of Helix pomatia, which, in addition to the normal set of reproductive organs present on the right side, possesses also on the left side a set of accessory male organs—namely, a penis and its retractor muscle, vas deferens, and flagellum. There is no trace of connection between these supernumerary organs and the ovotestis or the genital ducts of the right side.2. The normal and supernumerary penes are equally developed and are symmetrically placed with regard to the median plane of the head.3. The extra penis has the usual structure; it possesses a fully-developed copulatory organ and a muscular tubular introvert upon the inner sheath.4. The extra vas deferens opens at one end into the penis and at the other terminates blindly in the sub-epidermal tissue; the blind end is bound to the epidermis by a short cord of connective tissue.5. The extra flagellum is normal in size and in its internal structure.6. The penial nerves on both sides have a corresponding course from the cerebral ganglion to their distribution on the penes. Owing to defective preservation it was impossible to determine whether the fibres of the extra penial nerve arise from the ocular nerve, as is apparently the case, or whether they really arise from the pedal ganglion, as do those of the normal penial nerve.7. The penis opens into a short atrium which communicates with the exterior by a genital aperture of normal size and shape. This supernumerary genital aperture occupies a position on the left side exactly corresponding to that of the normal one on the right side. About 2·5 mm. posterior and slightly dorsal to it is the blind end of the vas deferens, which is situated close to the dorsal margin of the epidermal groove, which traverses the anterior portion of the animal.8. In the duplication of the penis and its associated structures this snail presents an example of lateral homoeosis. The only comparable cases recorded in the Mollusca are a Pteropod with paired penes (see Addendum, p. 327) and a specimen of Moschites cirrosa, in which not only was the third right arm hectocotylised as usual, but the third left one also.9. The supplementary vas deferens and the retracted penis form a U-shaped loop, both ends of which are in contact with the epidermis, and so closely resemble the corresponding structures figured by Plate in the primitive Pulmonate, Pythia scarabeus, that these organs may be described as having identical relations in the two forms, except that in the supplementary organs of Helix the vas deferens has no actual opening at its epidermal end and that it bears a flagellum which is not present in Pythia. It is suggested that the supplementary organs of Helix, having been able to develop free from the disturbing influence of the vagina, oviduct, and their accessory structures (which on the right side have been secondarily moved forwards in phylogeny), have assumed a condition closely resembling that which they would present in the ancestral form in which male and female apertures were some distance apart. The form of the extra organs (the vas deferens having a close connection at one end with the epidermis), which, it is suggested, might also be assumed by the corresponding normal organs if they were also free to develop independently of the female structures, supports the view that the present condition of the genital ducts in Helix and in other Stylommatophora, has been derived from a condition existing in the ancestral form in which the vas deferens and penis were connected with the primitive genital opening by means of a lateral groove, such as is still found in Pythia.10. Consideration of this and of other abnormalities which have been described in the Pulmonata leads to the conclusion that the penis develops as an epidermal structure which in Helix and other Stylommatophora is closely associated with, and is secondarily carried inwards by, the invaginating atrium. In proterogynously hermaphrodite forms, especially in those in which the shell is depressed, reduced, or absent, the development of the penis rudiment may be postponed until the male elements in the gonad are further developed.