Ascidian Larvae Discriminate Nano-Scale Difference in Surface Structures During Substrate Selection for Settlement.

Planktonic larvae of sessile metazoans select substrates for settlement based on various factors. larvae (Ascidiacea: Phlebobranchia: Ascidiidae) showed a negative preference for nano-scale nipple arrays (dense arrays of papillae-like nanostructures approximately 100 nm in height). To clarify whether ascidian larvae discriminate between nano-structure sizes for substrate selection, three different sizes of periodic nano-folds were fabricated using two-beam interference exposure, and substrate selection assays were performed on the three types of nano-folds and flat surfaces made of the same material.

Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, and .

In Phlebobranchiata ascidians, oocytes and spermatozoa are stored in the oviduct and spermiduct, respectively, until spawning occurs. Gametes in the gonoducts are mature and fertilizable; however, it was found that the gametes of the ascidians and could not undergo fertilization in the gonoductal fluids. The body fluids of the ascidians, especially in the gonoducts, were much more acidic (pH 5.

Wettability and Substrate Selection in the Larval Settlement of the Solitary Ascidian (Phlebobranchia: Ascidiidae).

For marine benthic animals, the selection of substrate by larvae is important for their survival, with early post-settlement mortality often being affected by the microenvironment where they settle. We tested the substrate preference of the larvae of the ascidian toward nine commercially available substrates. In the present assay, the larvae settled on one of four substrates for seven substrate combinations with different wettabilities; we counted the number of settled larvae on each of the four substrates, and Manly's selection indices were compared to determine the preference rank of each substrate.

Cytoplasmic UV-R Absorption in an Integumentary Matrix (tunic) of Photosymbiotic Ascidian Colonies.

In didemnid ascidians with cyanobacterial symbionts, the tunic has a specific peak absorbing ultraviolet radiation (UV-R) due to the presence of ultraviolet (UV)-absorbing compounds, which probably include mycosporine-like amino acids (MAAs). The UV-R absorbing tunic is supposed to protect the symbionts in the common cloacal cavity of the host colony. The histological distribution of UV-R absorption in the tunic was examined using a UV light microscope equipped with a digital camera, from which the low-pass filter of the UV-sensitive image sensor was removed.

Species-specificity of sperm motility activation and chemotaxis: a study on ascidian species.

Egg-derived sperm-activating factors and attractants activate sperm motility and attract the sperm, respectively. These phenomena constitute the first communication signaling between males and females in the process of fertilization in many animals and plants, and in many cases, these are species-specific events. Thus, sperm motility activation and chemotaxis may act as a safety process for the authentication between conspecific egg and sperm, and help to prevent crossbreeding.

Role of Mos/MEK/ERK cascade and Cdk1 in Ca2+ oscillations in fertilized ascidian eggs.

Intracellular calcium ion concentration ([Ca(2+)](i)) transients are observed in the fertilized eggs of all species investigated so far, and are critical for initiating several events related to egg activation and cell cycle control. Here, we investigated the role of the Mos/MEK/ERK cascade and Cdk1 on Ca(2+) oscillations in fertilized ascidian eggs. The egg of the ascidian Phallusia nigra shows [Ca(2+)](i) oscillations after fertilization: Ca(2+) waves immediately following fertilization (phase I), and [Ca(2+)](i) oscillations between the first and second polar body extrusions (phase II).

Early milk availability modulates the activity of choline acetyltransferase in the cerebral cortex of rats.

The purpose of the present study was to investigate the effect of milk in the early stage of lactation on the maturation of cholinergic neurons in the cerebral cortex of rats. Pups were removed from their mothers immediately following parturition and placed with foster dams at days 5-7 of lactation. At days 18 and 56 after birth, the activity of choline acetyltransferase (ChAT), an enzyme responsible for acetylcholine synthesis, in different areas of the cerebral cortex was examined by high-performance liquid chromatography electrochemical detection.

Induction of cholinergic differentiation by 5-azacytidine in NG108-15 neuronal cells.

The DNA-demethylating agent 5-azacytidine (5-azaC) causes extensive genomic demethylation of 5-methyl-cytosine residues and reduces DNA methyltransferase activity in cells. This study evaluated the effect of 5-azaC on neuronal differentiation in proliferating NG108-15 neuronal cells, which exhibit cholinergic traits. The expression of choline acetyltransferase, an enzyme responsible for acetylcholine synthesis, was increased at both the mRNA and protein level, and neurite outgrowth was markedly induced with an increase of neurofilament-heavy chain protein, in the 5-azaC-treated cells.

Functional development of oligodendrocytes and open-field behavior in developing rats: an approach using monoclonal antibody to immature oligodendrocytes.

To examine the relation between functional development of oligodendrocytes and open-field behavior during the postnatal period, a mouse monoclonal antibody termed 14F7, which predominantly labels stage-specific immature oligodendrocytes, was employed. Antibody 14F7 was administered intraperitoneally into male pups on day 3 and 4 after birth. The open-field test was performed on days 12 and 18 of the postnatal period.

Signaling pathway from [Ca2+]i transients to ooplasmic segregation involves small GTPase rho in the ascidian egg.

Intracellular Ca2+ transients occur at fertilization in the eggs of all animal species and are thought to be critical for the initiation of several events in egg activation. The rho family of small GTPases are known to organize and maintain the actin filament-dependent cytoskeleton, and rho is involved in the control mechanism of cytokinesis. In the ascidian Ciona savignyi, the first step of ooplasmic segregation observed just after fertilization is cortical contraction with egg deformation, mediated by the cortical actin filaments.

Effect of estradiol and FBS on PRL cells, GH cells, and PRL/GH cells in primary cultures of pituitary cells from prenatal rats.

The effects of estradiol (E2) treatment on prolactin (PRL) cells, GH cells, and PRL/GH cells in immature pituitary cells were determined using primary cultures from prenatal rats and immunocytochemistry with fluorescent antibodies. Anterior pituitaries obtained from fetuses on day 22 of pregnancy were monodispersed and cultured in chemically defined medium or medium containing 10% fetal bovine serum (FBS). After pre-incubation for 24 hr, E2 (final concentrations were 0 M, 10(-8) M, 10(-7) M, and 10(-6) M) was added into each medium.

Developmental profile of prolactin cells in the anterior pituitary of postnatal rats during the lactational stage.

Changes in prolactin (PRL)-, growth hormone (GH)- and PRL/GH-containing cells in the anterior pituitary of pre- and postnatal male and female rats were determined using immunocytochemistry with double fluorescent antibodies. The pituitary glands from a fetus on Day 20 of gestation and pups on Days 0, 1, 4, 7, 12, and 20 of the postnatal period with sex distinction were monodispersed and subjected to immunocytochemistry. Following immunostaining, the three types of cells described above were counted (i.

Role of two series of Ca2+ oscillations in activation of ascidian eggs.

Changes in [Ca2+]i are an essential factor regulating egg activation. Matured ascidian eggs are arrested at metaphase I, and two series of [Ca2+]i transients have been observed after fertilization: Ca2+ waves just after fertilization (Series I) and [Ca2+]i oscillation between the first and second polar body extrusion (Series II). We investigated mechanisms involved in the elevation of [Ca2+]i and the role of the [Ca2+]i transients during egg activation in Ciona savignyi.

Exogenous oxytocin attenuates suckling-induced prolactin release but not maternal or infant behavior in lactating rats.

The influence of exogenous oxytocin (OT) on maternal and infant behavior over 60 min of suckling, which followed 6 h of isolation, was investigated on Day 12 of lactation in rats. Mothers administered 1 IU of OT or saline through an indwelling atrial catheter and their litters indicated a similar nursing and suckling pattern, which was estimated by the crouching time of the mothers and the number of stretch reactions performed by the litters during a suckling period. To assess the alteration of the suckling intensity by OT administration, the plasma prolactin (PRL) level was determined by an Nb2 lymphoma cell bioassay.

Plasma progesterone concentrations during pregnancy and lactation in Mongolian gerbils (Meriones unguiculatus).

Plasma progesterone (P4) concentrations during pregnancy and lactation in Mongolian gerbils were measured by enzymeimmunoassay (EIA). The P4 concentration was found to increase rapidly after mating and reach a peak on day 6 of pregnancy. The maximum level (166.

Changes in prolactin bioactivity of milk following isolation from litter and oxytocin administration in rats.

Changes in prolactin (PRL)-like bioactivity in rat milk after a longer isolation of litters and the effects of oxytocin (OT) were determined by Nb2 lymphoma cell bioassay and compared with the immunoreactivity using an enzyme immunoassay. First, we confirmed the appropriate dilution rates of rat milk which could neutralize the influence of an antimitogenic factor(s) in milk to Nb2 lymphoma cell proliferation. To prolong the litter removal, i.

Effect of Ca on deformation, polar body extrusion and pronucleus formation in the egg of the ascidian, Ciona savignyi.

Cortical deformation and polar body extrusion are the principal events that occur at fertilization in the ascidian egg. We demonstrated that the intracellular Ca concentration ([Ca ] ) in the fertilized egg of Ciona savignyi increased at egg deformation (main peak) and then several small Ca spikes (1st spikes) appeared before the first polar body extrusion. Brief Ca spikes (2nd spikes), then appeared in the period between the first and second polar body extrusion.

Acetylcholine in the hippocampus during the discrimination learning performance in a rat model of chronic cerebral ischaemia.

Acetylcholine (ACh) release in the hippocampus of Wistar strain rats with permanent bilateral occlusion of the common carotid arteries was examined during a discrimination learning task using a microdialysis method. Such occlusion resulted in obvious impairment of the discrimination performance. The state, the basal value and released patterns, of ACh in the hippocampus differed in the sham-operated control and the experimental group, while ACh release was elevated during the dialysis experiment in both groups.

Effect of exogenous oxytocin on the leakage of lactose from the mammary gland and on suckling-induced plasma prolactin in the lactating rat.

The leakage of lactose from the mammary gland into plasma and the increase in the suckling-induced concentration of prolactin in the plasma of oxytocin-injected lactating rats suckling different numbers of pups were investigated. Rats nursing eight pups were isolated from their litter for 6 h and injected i.v.

Oocyte Maturation and Furrow Formation in an Unfertilized Egg by Fusion with a Fertilized Egg or Blastomeres in the Ascidian, Ascidia sydneiensis divisa: (ascidian egg/cell fusion/oocyte maturation/polar body extrusion/furrow formation).

A technique for fusing an ascidian egg with blastomeres using a chemical fusiogen was established and then used to identify cytoplasmic factors that regulate the process of oocyte maturation in ascidian eggs. Unfertilized eggs fused with fertilized eggs or blastomeres in hypotonic artificial sea water containing 20% polyvinyl alcohol within 10 min. After fusion polar bodies were extruded from the unfertilized portion of the fused eggs.

Changes with age of mammary glands in male and female soft-furred rat, Millardia meltada, in relation to prolactin and testosterone.

The soft-furred rat, millardia (Millardia meltada), is characterized by the development of androgen-dependent mammary tumours only in males. The age-related changes of the activities of thymidylate synthetase (TS) and thymidine kinase (TK), which contribute to DNA synthesis through de novo and salvage pathways, respectively, and structure in the mammary glands were studied in both males and females of this species between 5-28 months of age. While TK activity had no relation to age, TS activity decreased with age in males.

Effects of 6-methylenetestosterone acetate on spontaneous mammary tumourigenesis in SHN mice.

The effects of 6-methylenetestosterone acetate (MTA), an androgen derivative, on spontaneous mammary tumourigenesis were studied in a high mammary tumour strain of SHN virgin mice. AT 5-6 months of age female litter mates were divided into the experimental and the control mice. The experimental mice were given subcutaneous implantations of Silastic capsules containing MTA (MTA1 group) and non-tumourous mice received additional Silastic capsules after 2 months (MTA2 group) followed by MTA pellet implantation to non-tumourous animals a further 2 months later (MTA3 group).

Cause of pregnancy-dependent mammary tumour-induced suppression of lactation in GR/A mice.

To clarify the cause of pregnancy-dependent mammary tumour (PDMT)-induced suppression of lactation due to the retardation of mammary gland growth, we studied the following: (I) mammary gland growth at the end of pregnancy in mice with PDMT [PDMT(+)] in comparison with mice without PDMT [PDMT(-)] and (II) effects of PDMT removal at the end of pregnancy on mammary gland growth and function. In Experiment I, little difference was observed between PDMT(-) and PDMT(+) groups in mammary DNA content and plasma level of lactogenic hormone or progesterone at the end of pregnancy, indicating that the retardation of mammary gland growth by PDMT does not occur during pregnancy. In Experiment II, the surgical removal of PDMT 1 or 2 days before parturition resulted in a complete restoration of mammary gland growth and lactation.

Suppression of lactation by pregnancy-dependent mammary tumors in GR/A mice.

Pregnancy-dependent mammary tumors (PDMT) in GR/A mice appear during pregnancy, disappear soon after parturition, and appear again during subsequent pregnancies. The retardation of pup growth, an indication of the level of milk production, was also observed with the advance of lactation numbers in this strain. This study was performed to elucidate the relationship between PDMT and lactational performance.