Zur Geschlechtsbestimmung und Gametogenese von Bonellia viridis Rolando

Development ◽  
1974 ◽  
Vol 32 (1) ◽  
pp. 169-193
Author(s):  
Von Rudolf Leutert
Keyword(s):  
Sea Water ◽  
Sex Differentiation ◽  
Follicle Cells ◽  
Sensitive Period ◽  
Nurse Cells ◽  
Larval Life ◽  
Coelomic Cavity ◽  
Male And Female ◽  
Large Numbers ◽  
Electron Microscopical

Sex differentiation and gametogenesis in Bonellia viridis Rolando Large numbers of trochophore larvae of Bonellia viridis (Echiurida) were cultivated either in pure sea water (‘Glaszuchten’) or in sea water containing an intact or fragmented proboscis of an adult female (‘Rüsselzuchten’). The ability of these larvae to differentiate into males or females was investigated. Sex determination for the majority (43–83 %) is metagamic and phenotypic. These findings therefore confirm the results of Baltzer and disprove those of Wilczynski. When larvae are exposed to the action of the female proboscis, 76 % become males. The sensitive period during which this determination can take place lasts from day 3 to day 16 of larval life. Exceptions to this rule are discussed. The gametogenesis of Bonellia viridis has been investigated by electron microscopical methods. In early stages the oogonia of the ovary are already in syncytial contact with the nurse cells. The possible functions of the nurse cells and follicle cells are discussed. Electron micrographs failed to reveal two types of eggs (male- and female-determined eggs, according to Wilczynski). Spermiogenesis in Bonellia is described. The spermatogonia are situated in paired clusters in the coelomic cavity, and form a syncytial complex. After completion of spermiogenesis, the spermatozoa abandon their syncytial contact. The fine structure of ripe spermatozoa is described and discussed.

Oogenesis in Crustaceans: Ultrastructural Aspects and Selected Regulating Factors

2020 ◽  
pp. 29-59
Author(s):  
Mariusz K. Jaglarz ◽  
Szczepan M. Bilinski
Keyword(s):  
Great Majority ◽  
Follicle Cells ◽  
Nurse Cells ◽  
Germline Development ◽  
Cellular Processes ◽  
Ultrastructural Studies ◽  
Large Numbers ◽  
Oocyte Cytoplasm ◽  
Germline Cells ◽  
Female Germline

This chapter explores ultrastructural aspects of crustacean oogenesis. It focuses on various cellular processes associated with female germline development in selected crustacean groups. Oogenesis in crustaceans comprises four stages: proliferation of germline cells, previtellogenesis, vitellogenesis, and formation of egg coverings. The greater part of oogenesis occurs in the ovary. In Crustacea, two structurally and functionally distinct types of ovary are recognized: panoistic and meroistic. In panoistic ovaries, all germline cells differentiate into oocytes, and this type of ovarian organization occurs in a great majority of crustaceans, including Malacostraca. In contrast, in the meroistic ovaries, oogonial cells are connected by intercellular bridges and form characteristic linear cysts. Within each cyst, only one cell becomes an oocyte, and the remaining cells differentiate into nurse cells. Meroistic ovaries are typical for Branchiopoda and Ostracoda: Podocopida. Ultrastructural studies reveal that the nucleus and cytoplasmic organelles of the oocyte are highly synthetically active in the panoistic ovary, whereas in the meroistic type, oocyte development is supported, to some extent, by accompanying nurse cells. During previtellogenesis, oocytes accumulate large numbers of various organelles, e.g. ribosomes, mitochondria, and cisternae of endoplasmic reticulum. The oocyte cytoplasm also contains characteristic disc-shaped bodies and cortical granules. A comparative analysis of the proteinaceous yolk formation in different crustaceans reveals two distinct types of vitellogenesis (autosynthesis and heterosynthesis), and indicates that a mixed type prevails in these arthropods. In most crustacean species, germline cells associate with somatic follicle cells that may fulfill several functions during oogenesis.

scholarly journals Possible Epigenetic Origin of a Recurrent Gynandromorph Pattern in Megachile Wild Bees

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 437
Author(s):  
Daniele Sommaggio ◽  
Giuseppe Fusco ◽  
Marco Uliana ◽  
Alessandro Minelli
Keyword(s):  
Current Knowledge ◽  
Sex Differentiation ◽  
General Pattern ◽  
Body Parts ◽  
Wild Bees ◽  
Male And Female ◽  
Female Phenotype ◽  
In The Wild ◽  
Gene Transcripts ◽  
Individual Body

Gynandromorphs, i.e., individuals with a mix of male and female traits, are common in the wild bees of the genus Megachile (Hymenoptera, Apoidea). We described new transverse gynandromorphs in Megachile pilidens Alfkeen, 1924 and analyze the spatial distribution of body parts with male vs. female phenotype hitherto recorded in the transverse gynandromorphs of the genus Megachile. We identified 10 different arrangements, nine of which are minor variants of a very general pattern, with a combination of male and female traits largely shared by the gynandromorphs recorded in 20 out of 21 Megachile species in our dataset. Based on the recurrence of the same gynandromorph pattern, the current knowledge on sex determination and sex differentiation in the honey bee, and the results of recent gene-knockdown experiments in these insects, we suggest that these composite phenotypes are possibly epigenetic, rather than genetic, mosaics, with individual body parts of either male or female phenotype according to the locally expressed product of the alternative splicing of sex-determining gene transcripts.

scholarly journals Programming of the reproductive axis by hormonal and genetic manipulation in mice

Reproduction ◽  
2018 ◽  
Author(s):  
Susana B Rulli ◽  
María Julia Cambiasso ◽  
Laura D Ratner
Keyword(s):  
Sex Chromosome ◽  
Genetic Manipulation ◽  
Sex Differentiation ◽  
Reproductive Function ◽  
Gonadal Steroids ◽  
Critical Periods ◽  
Female Reproduction ◽  
Control Male ◽  
Male And Female ◽  
The Brain

In mammals, the reproductive function is controlled by the hypothalamic-pituitary-gonadal axis. During development, mechanisms mediated by gonadal steroids exert an imprinting at the hypothalamic-pituitary level, by establishing sexual differences in the circuits that control male and female reproduction. In rodents, the testicular production of androgens increases drastically during the fetal/neonatal stage. This process is essential for the masculinization of the reproductive tract, genitals and brain. The conversion of androgens to estrogens in the brain is crucial for the male sexual differentiation and behavior. Conversely, feminization of the brain occurs in the absence of high levels of gonadal steroids during the perinatal period in females. Potential genetic contribution to the differentiation of brain cells through direct effects of genes located on sex chromosomes is also relevant. In this review, we will focus on the phenotypic alterations that occur on the hypothalamic-pituitary-gonadal axis of transgenic mice with persistently elevated expression of the human chorionic gonadotropin hormone (hCG). Excess of endogenously synthesized gonadal steroids due to a constant hCG stimulation is able to disrupt the developmental programming of the hypothalamic-pituitary axis in both transgenic males and females. Locally produced estrogens by the hypothalamic aromatase might play a key role in the phenotype of these mice. The “four core genotypes” mouse model demonstrated a potential influence of sex chromosome genes in brain masculinization before critical periods of sex differentiation. Thus, hormonal and genetic factors interact to regulate the local production of the neurosteroids necessary for the programming of the male and female reproductive function.

Sex, Gonad Development and Seasonal Gonad Changes in Paphia staminea Conrad

1943 ◽  
Vol 6b (2) ◽  
pp. 140-151 ◽  
Author(s):  
D. B. Quayle
Keyword(s):  
British Columbia ◽  
Sex Differentiation ◽  
Time Lag ◽  
Gonad Development ◽  
Follicle Cells ◽  
Active Growth ◽  
Spawning Cycle ◽  
Sex Cells

In the little-neck clam, Paphia staminea, as occurring in British Columbia waters, the first sign of the gonad was found in individuals slightly over 1 mm. in length. Sex differentiation occurs at lengths of 15 to 30 mm. or in 2nd or 3rd year. Maturity is achieved at 22 to 35 mm. P. staminea is not protandric. Seasonal gonad changes are: by end of October all active spawning over; by December to January tubules of ovary filled with follicle cells; active growth of sex cells reaches peak in March; first spawning in April and by September most clams spawned out. Male spawning cycle parallels that of female, with certain time lag apparent. Some males may remain in spawned-out state during most of winter.

scholarly journals Studies on the male and female copulatory apparatus of Trichuris globulosa (Nematoda, Trichuridae)

2007 ◽  
Vol 44 (4) ◽  
pp. 151-156 ◽  
Author(s):  
H. Kaur ◽  
C. Duggal
Keyword(s):  
Body Wall ◽  
Posterior Part ◽  
Male Body ◽  
Male And Female ◽  
Copulatory Apparatus ◽  
Electron Microscopical ◽  
Scanning Electron

AbstractThe process of copulation in Trichuris globulosa (see Linstow, 1901) Ransom, 1911 has been studied using morphological, histological and scanning electron microscopical techniques (Keilley et al., 1973). The ventral coiling of the posterior part of the male body around the female is achieved by specialized muscles of the ventral body-wall. The single simple pointed spicule emerges with the everting cirrus and acquires a J-shape. The spicule may help in keeping apart the cuticular brim of the non-spiny noneversible part of the vagina during insemination. The cloacal tube is long with a detached internal cuticle which is eversible to the outside as a cirrus. Eversion is brought about by the protrusion of the spicule and contraction of the muscles of the spicule pouch. During eversion part of the proximal cloacal tube is also extruded and forms the globular part of the cirrus. The globular part is covered with spines, which may help in retaining the male and female in copula. The vagina is differentiated into the proximal vagina uterine and distal vagina vera. The vagina vera has a distal eversible spiny part and a proximal noneversible unarmed part. In Trichuris globulosa, the vagina vera is shorter than the spicule.

maelstrom is required for an early step in the establishment of Drosophila oocyte polarity: posterior localization of grk mRNA

Development ◽  
1997 ◽  
Vol 124 (22) ◽  
pp. 4661-4671 ◽  
Author(s):  
N.J. Clegg ◽  
D.M. Frost ◽  
M.K. Larkin ◽  
L. Subrahmanyan ◽  
Z. Bryant ◽  
...  
Keyword(s):  
Nurse Cell ◽  
Egf Receptor ◽  
Mrna Localization ◽  
Follicle Cells ◽  
Rna Transport ◽  
Nurse Cells ◽  
Loss Of Function ◽  
Cell Fates ◽  
Early Step ◽  
Novel Protein

We describe a mutant, maelstrom, that disrupts a previously unobserved step in mRNA localization within the early oocyte, distinct from nurse-cell-to-oocyte RNA transport. Mutations in maelstrom disturb the localization of mRNAs for Gurken (a ligand for the Drosophila Egf receptor), Oskar and Bicoid at the posterior of the developing (stage 3–6) oocyte. maelstrom mutants display phenotypes detected in gurken loss-of-function mutants: posterior follicle cells with anterior cell fates, bicoid mRNA localization at both poles of the stage 8 oocyte and ventralization of the eggshell. These data are consistent with the suggestion that early posterior localization of gurken mRNA is essential for activation of the Egf receptor pathway in posterior follicle cells. Posterior localization of mRNA in stage 3–6 oocytes could therefore be one of the earliest known steps in the establishment of oocyte polarity. The maelstrom gene encodes a novel protein that has a punctate distribution in the cytoplasm of the nurse cells and the oocyte until the protein disappears in stage 7 of oogenesis.

Infection of the germ line by retroviral particles produced in the follicle cells: a possible mechanism for the mobilization of the gypsy retroelement of Drosophila

Development ◽  
1997 ◽  
Vol 124 (14) ◽  
pp. 2789-2798 ◽  
Author(s):  
S.U. Song ◽  
M. Kurkulos ◽  
J.D. Boeke ◽  
V.G. Corces
Keyword(s):  
High Frequency ◽  
Cytoplasmic Membrane ◽  
De Novo ◽  
Germ Line ◽  
High Rate ◽  
Follicle Cells ◽  
Nurse Cells ◽  
Perivitelline Space ◽  
Viral Particles ◽  
Secretory Apparatus

The gypsy retroelement of Drosophila moves at high frequency in the germ line of the progeny of females carrying a mutation in the flamenco (flam) gene. This high rate of de novo insertion correlates with elevated accumulation of full-length gypsy RNA in the ovaries of these females, as well as the presence of an env-specific RNA. We have prepared monoclonal antibodies against the gypsy Pol and Env products and found that these proteins are expressed in the ovaries of flam females and processed in the manner characteristic of vertebrate retroviruses. The Pol proteins are expressed in both follicle and nurse cells, but they do not accumulate at detectable levels in the oocyte. The Env proteins are expressed exclusively in the follicle cells starting at stage 9 of oogenesis, where they accumulate in the secretory apparatus of the endoplasmic reticulum. They then migrate to the inner side of the cytoplasmic membrane where they assemble into viral particles. These particles can be observed in the perivitelline space starting at stage 10 by immunoelectron microscopy using anti-Env antibodies. We propose a model to explain flamenco-mediated induction of gypsy mobilization that involves the synthesis of gypsy viral particles in the follicle cells, from where they leave and infect the oocyte, thus explaining gypsy insertion into the germ line of the subsequent generation.

scholarly journals Early life stress alters transcriptomic patterning across reward circuitry in male and female mice

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Catherine Jensen Peña ◽  
Milo Smith ◽  
Aarthi Ramakrishnan ◽  
Hannah M. Cates ◽  
Rosemary C. Bagot ◽  
...  
Keyword(s):  
Life Stress ◽  
Early Life ◽  
Cortical Plasticity ◽  
Early Life Stress ◽  
Stress Sensitivity ◽  
Sensitive Period ◽  
Male And Female ◽  
Reward Circuitry ◽  
Female Mice ◽  
Increase Risk

Abstract Abuse, neglect, and other forms of early life stress (ELS) significantly increase risk for psychiatric disorders including depression. In this study, we show that ELS in a postnatal sensitive period increases sensitivity to adult stress in female mice, consistent with our earlier findings in male mice. We used RNA-sequencing in the ventral tegmental area, nucleus accumbens, and prefrontal cortex of male and female mice to show that adult stress is distinctly represented in the brain’s transcriptome depending on ELS history. We identify: 1) biological pathways disrupted after ELS and associated with increased behavioral stress sensitivity, 2) putative transcriptional regulators of the effect of ELS on adult stress response, and 3) subsets of primed genes specifically associated with latent behavioral changes. We also provide transcriptomic evidence that ELS increases sensitivity to future stress through enhancement of known programs of cortical plasticity.

scholarly journals Comparative transcriptome analysis of male and female flowers in Spinacia oleracea L

BMC Genomics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Ning Li ◽  
Ziwei Meng ◽  
Minjie Tao ◽  
Yueyuan Wang ◽  
Yulan Zhang ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Transcriptome Analysis ◽  
Spinacia Oleracea ◽  
Sex Differentiation ◽  
Alternative Polyadenylation ◽  
Gender Development ◽  
Comparative Transcriptome ◽  
Male And Female ◽  
First Time ◽  
Female Flowers

Abstract Background Dioecious spinach (Spinacia oleracea L.), a commercial and nutritional vegetable crop, serves as a model for studying the mechanisms of sex determination and differentiation in plants. However, this mechanism is still unclear. Herein, based on PacBio Iso-seq and Illumina RNA-seq data, comparative transcriptome analysis of male and female flowers were performed to explore the sex differentiation mechanism in spinach. Results Compared with published genome of spinach, 10,800 transcripts were newly annotated; alternative splicing, alternative polyadenylation and lncRNA were analyzed for the first time, increasing the diversity of spinach transcriptome. A total of 2965 differentially expressed genes were identified between female and male flowers at three early development stages. The differential expression of RNA splicing-related genes, polyadenylation-related genes and lncRNAs suggested the involvement of alternative splicing, alternative polyadenylation and lncRNA in sex differentiation. Moreover, 1946 male-biased genes and 961 female-biased genes were found and several candidate genes related to gender development were identified, providing new clues to reveal the mechanism of sex differentiation. In addition, weighted gene co-expression network analysis showed that auxin and gibberellin were the common crucial factors in regulating female or male flower development; however, the closely co-expressed genes of these two factors were different between male and female flower, which may result in spinach sex differentiation. Conclusions In this study, 10,800 transcripts were newly annotated, and the alternative splicing, alternative polyadenylation and long-noncoding RNA were comprehensively analyzed for the first time in spinach, providing valuable information for functional genome study. Moreover, candidate genes related to gender development were identified, shedding new insight on studying the mechanism of sex determination and differentiation in plant.

Observations on a field outbreak of Pox Virus Infection in young Nile crocodiles (Crocodylus Niloticus)

1991 ◽  
Vol 62 (1) ◽  
pp. 26-29 ◽  
Author(s):  
F. W. Huchzermeyer ◽  
K. D.A. Huchzermeyer ◽  
J. F. Putterill
Keyword(s):  
Virus Infection ◽  
Histopathological Examination ◽  
Skin Lesions ◽  
High Morbidity ◽  
Microscopical Examination ◽  
Virus Particles ◽  
Large Numbers ◽  
Intracytoplasmic Inclusions ◽  
Electron Microscopical ◽  
Scanning Electron

A field outbreak of pox virus infection in juvenile Nile crocodiles (Crocodylus niloticus), in which high morbidity and negligible mortality occurred, is described. Histopathological examination of the skin lesions revealed numerous large intracytoplasmic inclusions in the dermis and a very mild dermal inflammatory reaction. Scanning electron microscopical examination of the skin revealed the presence of large numbers of virus particles in the inclusions. Skin lesions persisted for 5 to 6 months.

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