Population biology of crab Hapalogaster dentata parasitized by rhizocephalan Briarosaccus hoegi in the northwestern Sea of Japan.

We studied the population and reproductive characteristics of the stone crab Hapalogaster dentata (De Haan, 1849) (Anomura: Lithodidae) parasitized by Briarosaccus hoegi (Rhizocephala: Peltogastridae) from Peter the Great Bay (northwestern Sea of Japan) in 2023. The sex structure of the H. dentata population was female-biased and represented by 39.

Hemal sinus basal laminae contact sites: a possible route between gonadal lumen and myoepithelial cells in the gonad of the sea star Patiria pectinifera.

Sea stars are a group of marine invertebrates suitable for studying the hormonal regulation of reproduction and spawning. In spite of substantial progress in understanding how various substances such as 1-methyladenine act in their gonads, there are still many gaps concerning the fine details of their action. One such gap is how the gonadal wall contraction is induced.

The dopamine effect on sea urchin larvae depends on their age.

Activation of the dopamine type-D receptor in late gastrula of sea urchins is known to decrease the growth rate of post-oral arms of larvae, and, as a result, the phenotype of these larvae mimics that of larvae developing in the abundance of food. Our data indicate that the effect of dopamine on sea urchin larvae is stage-dependent. In our experiment, the early four-armed plutei (96 hours post fertilization, hpf) of Strongylocentrotus intermedius had substantially shorter post-oral arms if they developed from the larvae treated with dopamine at the early pluteus stage (48 hpf), when they had already formed the first dopaminergic neurons, as compared to the plutei from the larvae treated with dopamine at the mid to late gastrula stage (24 hpf), when they did not have any neurons yet.

Are myoepithelial cells confined to genital coelomic sinus in the gonads of sea stars?

An ultrastructural study of the gonadal wall in 10 sea star species from the orders Forcipulatida, Paxillosida, Spinulosida, Valvatida and Velatida has shown variations in the presence of myoepithelial cells in the visceral peritoneal epithelium. These cells have only been found in the peritoneal epithelium of the gonads in Aphelasterias japonica (Forcipulatida: Asteriidae), Asterias amurensis (Forcipulatida: Asteriidae), Distolasterias nipon (Forcipulatida: Asteriidae), Diplopteraster multipes (Velatida: Pterasteridae), Luidia quinaria (Paxillosida: Ctenodiscidae), and Pteraster sp. (Velatida: Pterasteridae).

Microscopic anatomy of gonadal area in the deep-sea clam Calyptogena pacifica (Bivalvia: Vesicomyidae) with emphasis on somatic cells.

Somatic cells in the gonadal area of male and female deep-sea clams, Calyptogena pacifica, were examined using light and transmission electron microscopy. Acini both at the pre-spawning stage and at the stage of active spermatogenesis were observed to be simultaneously present in sections through a male gonad. Oocytes of various degrees of maturity were simultaneously present in female acini.

External dsRNA Downregulates Anthocyanin Biosynthesis-Related Genes and Affects Anthocyanin Accumulation in .

Exogenous application of double-stranded RNAs (dsRNAs) and small-interfering RNAs (siRNAs) to plant surfaces has emerged as a promising method for regulation of essential genes in plant pathogens and for plant disease protection. Yet, regulation of plant endogenous genes via external RNA treatments has not been sufficiently investigated. In this study, we targeted the genes of chalcone synthase (CHS), the key enzyme in the flavonoid/anthocyanin biosynthesis pathway, and two transcriptional factors, MYBL2 and ANAC032, negatively regulating anthocyanin biosynthesis in .

Ultrastructural aspects of spermatogenesis in Calyptogena pacifica Dall 1891 (Vesicomyidae; Bivalvia).

The process of spermatogenesis and spermatozoon morphology was characterized from a deep-sea bivalve, Calyptogena pacifica (Vesicomyidae, Pliocardiinae), a member of the superfamily Glossoidea, using light and electron microscopy. Spermatogenesis in C. pacifica is generally similar to that in shallow-water bivalves but, the development of spermatogenic cells in this species has also some distinguishing features.

Effect of dopamine on early larvae of sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius.

Larvae of many echinoids are known to be phenotypically plastic and capable of changing the growth rate of their post-oral arms depending on the microalgae concentration in their habitat. As literature data show, developing larvae use chemosensation to detect algae in the environment and "adjust" the rate of growth of their post-oral arms through dopamine signaling. According to our results, dopamine has a significant effect on the post-oral arm growth in early larvae of two sea urchin species, Mesocentrotus nudus and Strongylocentrotus intermedius.

Distribution of Molecules Related to Neurotransmission in the Nervous System of the Mussel .

In bivalves neurotransmitters are involved in a variety of behaviors, but their diversity and distribution in the nervous system of these organisms remains somewhat unclear. Here, we first examined immunohistochemically the distributions of neurons containing different neurotransmitters, neuropeptides, and related enzymes, as well as the proliferative status of neurons in the ganglia of the mussel . H-Phe-Met-Arg-Phe-NH2 (FMRFamide), choline acetyltransferase (ChAT), γ-aminobutyric acid (GABA) and tyrosine hydroxylase (TH) were found to be expressed by neurons in all the ganglia, whereas serotonin (5-HT) neurons were found only in the cerebropleural and pedal, but not visceral ganglia.

Autophagy in nutrient storage cells of the Pacific oyster, Crassostrea gigas.

In oysters, nutrients are stored in a special type of cells referred to as vesicular-connective tissue cells (VCT-cells). These cells accumulate and provide nutrient to satisfy various needs of the organism, including gametogenesis. During the annual reproductive cycle, VCT-cells pass through a series of changes in their morphology associated with nutrients mobilization for developing germ cells.

Macroautophagy is involved in residual bodies formation during spermatogenesis in sea urchins, Strongylocentrotus intermedius.

An ultrastructural study of developing spermatids in sea urchins, Strongylocentrotus intermedius, showed that macroautophagy is involved in formation of residual bodies and removal of excessive cytoplasm by spermatids during spermatogenesis in this species. During late stages of spermatogenesis spermatids sequester excessive cytoplasm into vesicles, surrounded by a double membrane. Subsequently, these vesicles fused to one another into larger vacuoles, up to 1.

Morphology of nutrient storage cells in the gonadal area of the Pacific oyster, Crassostrea gigas (Thunberg, 1793).

Successful gametogenesis in invertebrates is tightly associated with functioning of specific nutrient-storing cells. In oysters, cells of vesicular connective tissue (VCT-cells), also referred to as storage cells, which form a meshwork around gonadal acini, are the major population of cells that accumulate and provide nutrients for developing gametes. During the annual reproductive cycle, populations of developing germ cells and VCT-cells demonstrate the inversely proportional size dynamics: the larger the acini, the smaller the VCT-cells.

Reinvestigation of epithelial lining of the genital coelomic sinus in asteroids. An ultrastructural study.

Ultrastructural study of gonadal muscles in sea star, Asterina pectinifera, showed that myoepithelial cells were located only in the epithelial lining of the genital coelomic sinus. No myoepithelial cells were found in the visceral peritoneal epithelium or within connective tissue layer of the outer sac. Morphology of the myoepithelial cells in gonads of A.

An ultrastructural study of testes permeability in sea urchins, Strongylocentrotus intermedius.

Permeability of testes in sea urchins, Strongylocentrotus intermedius, was investigated by using an electron-opaque tracer, lanthanum nitrate. This tracer is able to enter the basal compartment of germinative epithelium, where developing germ cells are located. However, its ability to penetrate the gonadal lumen was reduced.

A brief summary of neuroendocrine regulation of reproduction in sea stars.

Over than fifty years starfishes have been widely used as model for studying the mechanisms of cell cycle regulation, oocyte maturation and fertilization. Besides, significant work has been done to investigate the role of nervous system in the control of reproduction and spawning in these animals. Nowadays, sea stars represent one of the most thoroughly studied model for hormonal regulation of reproduction among invertebrates.

Biplexiform ganglion cells contact photoreceptors in the retina of the greenling Hexagrammos octogrammus.

The biplexiform cell (bpxRGC) is a relatively and recently discovered type of retinal ganglion cells. Like "ordinary" ganglion cells, bpxRGCs have dendrites arborizing within the inner plexiform layer. However, as distinct from other ganglion cells, they have dendrites ascending to the outer plexiform layer.

Selective resorption in nutritive phagocytes of the sea urchin Anthocidaris crassispina.

Phagocytic resorption during spermatogenesis was studied in the sea urchin Anthocidaris crassispina. Nutritive phagocytes in gonad absorbed both waste sperm cells and residual bodies discarded from maturing spermatids, and these materials were subsequently compartmented in heterophagosomes. Based on 180 heterophagosomes examined by transmission electron microscopy, over 99% of heterophagosomes contained either residual bodies or sperm cells only.