Sexual isolation and cuticular hydrocarbons in Drosophila elegans

In Drosophila elegans, partial sexual isolation has developed between the brown and black morphs, which are distributed allopatrically. The present study aims to understand how they discriminate between potential mates. Mating experiments show that the females of the two morphs differ in sexual signal(s) and the males discriminate using these differences. Body colouration is not used as a sexual cue in this species. Between the females of the two morphs, a large difference was observed in the percentages of 7-pentacosene and 9-pentacosene on the cuticle. Genetical analysis using recombinant inbred lines supported the possibility that the concentration of these pentacosenes plays a role in mate discrimination of these two morphs. However, males did not respond to killed females at all, suggesting that cuticular hydrocarbons of females are not the only cue for the induction of male courtship behaviour. It may be that unknown signals or substances are essential to induce male courtship and pentacosenes modulate the attractiveness of females, positively in the black morph and negatively in the brown morph. Drosophila elegans F1 offspring had intermediate characteristics in mate discrimination and hydrocarbon composition between the parental brown and black morph strains. The number of loci responsible for the differences in the concentration of pentacosenes and the male and female components in the mate recognition between these two morphs is suggested to be more than one.

Properties of the hatching enzyme from Xenopus laevis

Using an anti-(glutathione S-transferase-UVS.2 cDNA) Ig and uterine egg vitelline envelope (UEVE) protein of Xenopus laevis as probes, the hatching enzyme (HE) from Xenopus was solubilized in hatching medium and purified by gel-filtration and ion-exchange chromatography, and characterized in terms of its molecular mass and enzymatic properties. The hatching medium solubilized the UEVE and contained molecules reactive to the anti-(GST UVS.2) Ig against Xenopus HE. It was found that the HE had a molecular mass of 60 kDa, and often preparations also contained a 40-kDa form. The 60-kDa HE had a high hydrolytic and UEVE-solubilizing activity, and its activities against Boc-Leu-Gly-Arg-7-amino-4-methylcoumarin (-NH-Mec) and UEVE were inhibited by anti-(GST UVS.2) Ig in a dose-dependent manner. The 60-kDa form was easily autodigested into a 40-kDa form. The 40-kDa molecule alone had no detectable UEVE-solubilizing activity, even it still had high hydrolytic activity. It probably represents the main protease domain of the 60-kDa form after loss of two CUB repeats during autodigestion or digestion. The autodigestion of the 60-kDa molecule into 40-kDa molecule is probably a congenital behavior for successfully dissolving the embryo envelope during the hatching process. The two molecules may play different roles at different stages of the hatching process, during which they co-ordinate with each other to achieve complete solubilization of the embryo envelope, similar to the high and low choriolytic enzymes in medaka (Oryzias latipes). Their hydrolytic activity against Boc-Leu-Gly-Arg-NH-Mec was optimal at pH of 7.4, and with an apparent Km value of 200 micromol.L-1 at 30 degrees C. The HE is very sensitive to trypsin-specific inhibitors such as leupeptin, (4-amidino-phenyl)methane sulfonyl fluoride, diisopropyl fluorophosphate (DFP) and N-alpha-tosyl-L-lysylchloromethane (Tos-Lys-CH2Cl), indicates that it is a trypsin-type protease. The results on EDTA and some metal ions, combined with the occurrence of a astacin family metalloprotease-specific 'HExHxxGFxHE' sequence in the deduced HE amino-acid sequence, indicates that this HE is a Zn2+ metalloprotease.

Indication for histological examination of endometrium in breast carcinoma patients receiving tamoxifen therapy

OBJECTIVE

To investigate the effects of tamoxifen on the uterine endometrium and define the indications for histological examination of endometrium on the thickness of uterine endometrium and on the duration of tamoxifen therapy.

METHODS

The endometrial thickness was measured on the transvaginal ultrasonogram in 40 postmenopausal breast carcinoma patients receiving tamoxifen (tamoxifen group), and control group. Endometrial histological examination was carried out. Receiver operating characteristic (ROC) curve analysis was carried out.

RESULTS

Endometrial thickness in the tamoxifen group was 11.2 +/- 5.1 mm, and that of the control group was 3.8 +/- 2.1 mm. The incidence of endometrial abnormalities in the tamoxifen group was greater than that in control group. The cut off values derived from the ROC curve analysis were 9 mm for endometrial thickness, and 24 months for duration of tamoxifen therapy.

CONCLUSION

The histological examination of endometrium should be carried out if the endometrial thickness is more than 9 mm, or the duration of tamoxifen therapy is more than 24 months even if the patients do not have any symptoms.

Prominent immunogenicity of monosialosyl galactosylgloboside, carrying a stage-specific embryonic antigen-4 (SSEA-4) epitope in the ACHN human renal tubular cell line-a simple method for producing monoclonal antibodies against detergent-insoluble microdomains/raft

The binding of Shiga toxin (Stx) to Gb3Cer in detergent-insoluble microdomains (DIM)/raft of the ACHN human renal tubular cell line causes the temporal activation of the Src-family kinase Yes [1]. As a strategy for examining signaling mechanisms in DIM/raft, monoclonal antibodies (MAbs) are reliable tools for characterizing the constituent molecules in these microdomains. Thus, we employed DIM/raft suspensions of ACHN cells as an immunogen to develop MAbs. Simply subcutaneous injections of ACHN DIM/raft could elevate the serum titer after several boosts. The first screening was performed using dot-blot immunostaining with culture supernatants on a polyvinylidene difluoride (PVDF) membrane, on which DIM/raft or their chloroform/methanol (C/M) (2:1, v/v) extracts were dot-blotted. The next screening was performed by flowcytometric analysis of ACHN cells treated with or without a permeabilizing reagent. Many of the clones (21/31 clones=68%) thus obtained were also found to recognize to lipid fractions of the DIM/raft. Strikingly, all of the 21 clones that reacted to the lipid fraction were found to recognize monosialosyl galactosylgloboside (MSGG) or GL7, which carries the SSEA-4 epitope. Using DIM/raft as immunogens may enable us to easily obtain MAbs for glycolipids.

Phenobarbital following phototherapy for Crigler-Najjar syndrome type II with good fetal outcome: a case report

In the presence of severe hyperbilirubinemia in Crigler-Najjar syndrome Type II, a fetus is at risk for kernicterus. A 34-year-old woman, gravida 4, para 1, with Crigler-Najjar syndrome Type II was treated with phenobarbital administration following phototherapy during each of 2 pregnancies. Both infants were healthy and developed normally.

Immunohistochemical detection of calmodulin and calmodulin-dependent protein kinase II in the mouse testis

We reported previously that in mouse testis calmodulin-dependent protein phosphatase (calcineurin) is localised in the nuclei of round and elongating spermatids (Cell Tissue Res. 1995; 281: 273-81). In this study, we studied the immunohistochemical localisation of calcium/calmodulin-dependent protein kinase (CaM kinase II) using antibodies against CaM kinase IIgamma from chicken gizzard and specific antibodies raised against the amino acid sequence Ileu480-Ala493 of this enzyme, and compared it with the distribution of calmodulin. Indirect immunofluorescence was most concentrated in early spermatocytes and localised in the outermost layer of seminiferous tubules where the calmodulin level was relatively low. Measurements of immuno-gold particle densities on electron micrographs revealed that CaM kinase II is transiently increased in the nucleus of zygotene spermatocytes. These observations suggest the involvement of CaM kinase II in the meiotic chromosomal pairing process. An extremely high concentration of calmodulin in spermatogenic cells undergoing meiosis may not be directly related to activation of calmodulin-dependent kinases and phosphatases.

Homoiogenetic regulation through the ectoderm on localized expression of the hatching gland phenotype in the head area of Xenopus embryos

Ectoderm pieces explanted from embryos of Xenopus laevis were cultured and examined for differentiation of hatching gland cells, using immunoreactivity against anti-XHE (Xenopus hatching enzyme) as a marker. The anterio-dorsal ectoderm excised from stage 12-13 (mid-late gastrula) embryos developed hatching gland cells. Meanwhile, the posterio-, but not the anterio-dorsal ectoderm from stage 11 (early gastrula) embryos developed these cells, although it is not fated to do so during normogenesis. This hatching gland cell differentiation from stage 11 posterior ectoderm was not affected by conjugated sandwich culture with the mesoderm but was suppressed when explants contained an anterior portion of the ectoderm. Conjugated cultures of anterior and posterior portions of the ectoderm in various combinations indicated that differentiation of hatching gland cells from stage 11 posterior and stage 12 anterior portions was suppressed specifically by stage 11 anterior ectoderm. Northern blot analyses of cultured explants showed that XHE was expressed in association with XA-1, suggesting its dependence on the anteriorized state. These results indicate that the planar signal(s) emanating from stage 11 anterior ectoderm participates in suppression of the expression of the anteriorized phenotype so that an ordered differentiation along the anteroposterior axis of the surface ectoderm is accomplished.

Activation of Src family kinase yes induced by Shiga toxin binding to globotriaosyl ceramide (Gb3/CD77) in low density, detergent-insoluble microdomains

Shiga toxin (Stx) is an enterotoxin produced by Shigella dysenteriae serotype 1 and enterohemorrhagic Escherichia coli, which binds specifically to globotriaosylceramide, Gb3, on the cell surface and causes cell death. We previously demonstrated that Stx induced apoptosis in human renal tubular cell line ACHN cells (Taguchi, T., Uchida, H., Kiyokawa, N., Mori, T., Sato, N., Horie, H., Takeda, T and Fujimoto, J. (1998) Kidney Int. 53, 1681-1688). To study the early signal transduction after Stx addition, Gb3-enriched microdomains were prepared from ACHN cells by sucrose density gradient centrifugation of Triton X-100 lysate as buoyant, detergent-insoluble microdomains (DIM). Gb3 was only recovered in DIM and was associated with Src family kinase Yes. Phosphorylation of tyrosine residues of proteins in the DIM fraction increased by 10 min and returned to the resting level by 30 min after the addition of Stx. Since the kinase activity of Yes changed with the same kinetics, Yes was thought to be responsible for the hyperphosphorylation observed in DIM proteins. Unexpectedly, however, all of the Yes kinase activity was obtained in the high density, detergent-soluble fraction. Yes was assumed to be activated and show increased Triton X-100 solubility in the early phase of retrograde endocytosis of Stx-Gb3 complex. Since Yes activation by the Stx addition was suppressed by filipin pretreatment, Gb3-enriched microdomains containing cholesterol were deeply involved in Stx signal transduction.

Some magnesium salts and a mixture of magnesium and calcium salts accelerate skin barrier recovery

The effects of four different magnesium salts on the cutaneous barrier recovery rate after barrier disruption were evaluated. We spread an aqueous solution of each salt on the flank skin of hairless mice, occluded the area with a plastic membrane for 20 min, and then left the skin surface to dry. All of the magnesium salts, except magnesium bis(dihydrogen phosphate), accelerated barrier repair. We next estimated the effects of magnesium chloride aqueous solutions which contained calcium chloride at different molar ratios. When the calcium to magnesium ratio was lower than 1, the mixture accelerated barrier repair. The application of an aqueous solution of 10 mM magnesium chloride and 10 mM calcium chloride was found to hasten the barrier recovery more effectively than a solution of 10 mM magnesium chloride. These results suggest that the effects of these metal ions are different depending on the counter ion and/or the method of application.

Placenta previa increta penetrating the entire thickness of the uterine myometrium: ultrasonographic and magnetic resonance imaging findings

This is the first report of placenta previa increta in which the placenta villi penetrated the entire thickness of the uterine myometrium, but did not invade the pubocervical fascia. Ultrasonographic and magnetic resonance imaging findings are described.

Molecular basis for oviductin-mediated processing from gp43 to gp41, the predominant glycoproteins of Xenopus egg envelopes

Acquisition of fertilizability in Xenopus coelomic eggs is correlated with the conversion from coelomic to vitelline envelope during passage of the eggs through the pars recta portion of oviduct. The conversion includes processing of a major envelope constituent gp43 of coelomic envelopes to gp41 of vitelline envelopes by a trypsin-type protease, oviductin, which is secreted from the pars recta. Our recent sequencing analyses [Kubo et al., (1997): Dev Growth Diff 39:405-411] strongly suggested that the N-terminal portion of gp41 is exposed as a result of oviductin digestion. In this study, a monoclonal antibody specific to the predicted N-terminus of gp41 was raised by immunizing mice with a synthetic N-terminal hexapeptide (QLPVSP) coupled to keyhole limpet hemocyanin. The antibody specifically reacted to gp41, but not to gp43, indicating that Gln62 is exposed as the N-terminal amino acid of gp41 by oviductin-mediated cleavage of gp43 at Arg61 in GSR61. The C-terminal sequencing of gp43 and gp41 indicated that Arg373 in GSR373 as the C-terminus of gp41 is generated by cleavage of three amino acid (WNQ) residues from the C-terminus of gp43. The resulting polypeptide moiety of gp41 has a molecular mass of 33900 Da with 312 amino acid residues. We propose that oviductin possessing the substrate specificity of GSR simultaneously digests gp43 at Arg residues in GSR61 and GSR373 to generate the N- and C-terminus of gp41, respectively.

Analyses of oviductal pars recta-induced fertilizability of coelomic eggs in Xenopus laevis

The acquisition of fertilizability in coelomic eggs of Xenopus laevis has been shown to be correlated with the physical, biochemical, and ultrastructural alterations of the egg envelope [coelomic envelope (CE)] induced during the passage of eggs through the pars recta portion of the oviduct. However, no direct evidence that the pars recta renders eggs fertilizable has yet been presented. In this study, we show that coelomic eggs are highly fertilizable when they are incubated with continuous shaking for 4 h at 15 degrees C in pars recta extract (PRE) derived from females prestimulated by pregnant mare serum gonadotropin. The PRE from pituitary-stimulated Bufo japonicus was as potent as homologous PRE in rendering Xenopus eggs fertilizable. Incubation of coelomic eggs in PRE for 30 min induced a dramatic increase in the rates of sperm binding to the envelope to a level equivalent to that exhibited by the envelope from uterine eggs (VEs). The CE-to-VE ultrastructural conversion and a 43k-to-41k hydrolysis of the envelope glycoprotein component started 5 min after, and were completed by 15 min after, the start of incubation in PRE and were accompanied by an exposure of a new N-terminal sequence typical to gp41. Thus, the biochemical and ultrastructural conversions and the sperm-binding activity of the envelope induced by PREs, although being prerequisite, were not sufficient to render coelomic eggs fully accessible to fertilizing sperm.

Induction of selected lipid metabolic enzymes and differentiation-linked structural proteins by air exposure in fetal rat skin explants

The epidermal permeability barrier of premature infants matures rapidly following birth. Previous studies suggest that air exposure could contribute to this acceleration, because: (i) development of a structurally and functionally mature barrier accelerates when fetal rat skin explants are incubated at an air-medium interface, and (ii) occlusion with a water-impermeable membrane prevents this acceleration. To investigate further the effects of air exposure on epidermal barrier ontogenesis, we compared the activities of several key enzymes of lipid metabolism and gene expression of protein markers of epidermal differentiation in fetal rat skin explants grown immersed versus air exposed. The rate-limiting enzymes of cholesterol (HMG CoA reductase) and ceramide (serine palmitoyl transferase) synthesis were not affected. In contrast, the normal developmental increases in activities of glucosylceramide synthase and cholesterol sulfotransferase, responsible for the synthesis of glucosylceramides and cholesterol sulfate, respectively, were accelerated further by air exposure. Additionally, two enzymes required for the final stages of barrier maturation and essential for normal stratum corneum function, beta-glucocerebrosidase, which converts glucosylceramide to ceramide, and steroid sulfatase, which desulfates cholesterol sulfate, also increased with air exposure. Furthermore, filaggrin and loricrin mRNA levels, and filaggrin, loricrin, and involucrin protein levels all increased with air exposure. Finally, occlusion with a water-impermeable membrane prevented both the air-exposure-induced increase in lipid enzyme activity, and the expression of loricrin, filaggrin, and involucrin. Thus, air exposure stimulates selected lipid metabolic enzymes and the gene expression of key structural proteins in fetal epidermis, providing a biochemical basis for air-induced acceleration of permeability barrier maturation in premature infants.

Physicochemical and functional comparison of Xenopus laevis nucleoplasmin obtained from oocytes and from overexpression in bacteria

We compare the physicochemical and functional characteristics of nucleoplasmin obtained from Xenopus laevis oocytes and by bacterial overexpression of a plasmid containing the nucleoplasmin gene. The comparison shows that, while the secondary structure of the protein is not affected by the method used to obtain this protein, the bacterial expressed form exhibits a marked tendency to form large aggregates and an impaired ability to displace protamines from sperm nuclei. These results add a word of caution to the indiscriminate use, in functional or structural (crystallographic) studies, of bacterially overproduced proteins that have been end-terminally tagged with polyhistidine.

Characterization of the hatching enzyme from embryos of an anuran amphibian, Rana pirica

The culture medium in which prehatching embryos of the frog, Rana pirica, were cultured (hatching medium) solubilized the vitelline coat (VC) of unfertilized eggs and contained molecules reactive to antibodies (anti-UVS.2) against the Xenopus hatching enzyme (HE). The hydrolyzing activity of the hatching medium against Pro-Phe-Arg-MCA was inhibited dose-dependently by the same antibodies. Using anti-UVS.2 as a probe, we purified two distinct 56 kDa molecules exhibiting Pro-Phe-Arg-MCA hydrolyzing activity. These 56 kDa molecules, which were separable on anion exchange chromatography, were the same with respect to VC solubilizing activity and a substrate specificity for various MCA-peptides, and they were regarded as charge isomers that function as the HE. The hydrolyzing activity against Pro-Phe-Arg-MCA of HE was optimal at pH of 7.6, with the apparent Km value of 250 microM at 30 degreesC. The activity was strongly inhibited by DFP and EDTA, and was accelerated by extremely low concentrations of Mg2+ and Zn2+, indicating the serine protease and metalloprotease nature of the HE. The HE was glycosylated and was present as a putative proenzyme form of 63 kDa.

Histone H1 binding does not inhibit transcription of nucleosomal Xenopus laevis somatic 5S rRNA templates

It has long been proposed that selective binding of histone H1 is, in part, responsible for the differential developmental regulation of the oocyte and somatic 5S rRNA genes in Xenopus laevis. In this study we show that histone H1 binds both oocyte and somatic genes equally after reconstitution into mononucleosomes or oligonucleosome arrays. Furthermore, we show that the binding of histone H1 selectively represses only oocyte gene transcription and that an RNA polymerase III transcription complex is able to initiate transcription of nucleosomal somatic templates regardless of whether histone H1 is present. These results support a model in which the differential regulation of the 5S rRNA genes is not simply due to the prevention of histone H1 binding by transcription complexes on the somatic genes, but rather to a difference in the histone H1 interaction with the somatic and oocyte genes.

Properties of specific binding site of myotoxin a, a powerful convulsant, in brain microsomes

Myotoxin a, a small basic polypeptide from prairie rattlesnakes (Crotalus viridis viridis), induces myonecrosis and binds to a single class of binding sites in skeletal muscle sarcoplasmic reticulum. In the present study, [125I]myotoxin a with a high specific activity was prepared and it was shown to bind mainly to microsomes in rat whole brain. [125I]Myotoxin a was further shown to bind to microsomes prepared from all regions tested in brain. Its specific binding to whole brain microsomes was of approximately 1.9 times lower affinity (KD = 0.76 microM; Bmax = 13.1 nmol/mg) than that to skeletal muscle sarcoplasmic reticulum. [125I]Myotoxin a binding to brain microsomes was displaced by unlabeled myotoxin a with an IC50 value of 4.5 microM. [125I]Myotoxin a binding was markedly reduced by treatment of microsomes with trypsin, suggesting that the binding site of [125I]myotoxin a is partially proteins. The binding was significantly inhibited by Mg2+ at concentrations above 1 mM. Having looked at several drugs, we noted that [125I]myotoxin a binding was noncompetitively inhibited by spermine, whereas it was enhanced by heparin. On the other hand, the i.c.v. injection of myotoxin a in mice induced potent convulsive effects at 0.05 nmol/mouse or more. This paper is the first to show that the specific binding site of myotoxin a is present in mouse brain and that myotoxin a is a novel peptidic convulsant in mice.

How Drosophila species acquire cold tolerance--qualitative changes of phospholipids

Phospholipids of many cold-tolerant organisms have been reported to contain more unsaturated fatty acids than cold-susceptible organisms, a phenomenon known to maintain membrane fluidity at low temperature. However, we have obtained results to the contrary through a comparison of the membrane phospholipids of six temperate and subtropical species belonging to the Drosophila melanogaster species group. With enhancement of cold tolerance, the percentages of monoenoic acids increased but the percentages of dienoic acids decreased, that is, the number of double bonds in the phospholipid decreased without a marked variation in the percentages of unsaturated fatty acids. Concomitantly, the percentage of fatty acids containing 16 carbon atoms increased, while that of fatty acids with 18 carbon atoms decreased. Since phosphatidylethanolamine is a dominant phospholipid in Drosophila, these changes probably contribute to keeping the homeoviscosity of the cellular membranes in a manner different to that in phosphatidylcholine-rich membranes, thereby increasing cold tolerance.

The histone binding protein nucleoplasmin does not facilitate binding of transcription factor IIIA to nucleosomal Xenopus laevis 5S rRNA genes

In an attempt to understand the mechanism by which transcription factors compete with histone octamers for cognate binding sites in chromatin, the effect of the histone binding protein nucleoplasmin on the binding of TFIIIA to nucleosomal 5S rRNA genes was tested. In this study, it was shown that, despite the previously reported nucleosome remodeling ability of nucleoplasmin, the binding of TFIIIA to nucleosomal DNA cannot be facilitated by this protein. Furthermore, it was demonstrated that nucleoplasmin cannot overcome nucleosome mediated repression of transcription of reconstituted 5S rRNA genes. In contrast to earlier work, this study used a homologous system composed of the 5S rRNA gene, nucleoplasmin, and TFIIIA from Xenopus laevis.

A major glycoprotein of Xenopus egg vitelline envelope, gp41, is a frog homolog of mammalian ZP3

A predominant glycoprotein in the vitelline envelope (VE) of the anuran Xenopus laevis is gp41, known to be proteolytically converted from gp43 of the coelomic egg envelope concomitant with the acquisition of egg fertilizability. To characterize the protein core of gp41, purified gp41 from VE was digested with lysyl endopeptidase, and peptides isolated from the digests were sequenced for amino acids to design degenerate primers for polymerase chain reaction. By reverse transcription-polymerase chain reaction with a poly(A)+ RNA from the ovary of an ovulated female Xenopus, a specifically amplified band was obtained and sequenced. The upstream and downstream sequences of the sequenced region were completed by 5'- and 3'-rapid amplification of cDNA ends, respectively. The cDNA, referred to as gp43 cDNA, comprises 1423 base pairs and contains one open reading frame with a sequence for 460 amino acids. The predicted amino acid sequence of gp43 cDNA has a close similarity with that of mammalian ZP3. Northern blot and in situ hybridization studies indicated that gp43 mRNA is expressed in oocytes, particularly in the previtellogenic oocytes. A comparison of the N-terminal sequences of gp41 and gp43 strongly suggested that gp41 is generated at least by processing of the N-terminal portion of gp43 with oviductin.

Histone H1 variants as sperm-specific nuclear proteins of Rana catesbeiana, and their role in maintaining a unique condensed state of sperm chromatin

Amino acid analyses of nuclear basic proteins of an anuran amphibian, Rana catesbeiana, revealed that they are comprised of a full set of core histones and three types of lysine-rich, sperm-specific proteins. On the basis of their amino-acid compositions and partial amino-acid sequences of their trypsin-resistant cores, the sperm-specific proteins could be defined as members of the histone H1 family. Both micrococcal nuclease digestion and electron microscopy indicated that sperm chromatin consists of nucleosomal and fibrillar DNA structures which are irregularly interspersed with each other. When sperm nuclei were incubated with nucleoplasmin, nuclei decondensed to some extent, and the sperm-specific H1s were removed, but not completely. The residual sperm-specific histone H1 variants were also found in reconstituted male pronuclear chromatin, comprising regularly spaced nucleosomes. We conclude that sperm-specific histone H1 variants are essential for chromatin condensation in the sperm nuclei, but that their complete removal is not necessary for the remodeling into somatic chromatin that takes place after fertilization.

Epidermal steroid sulfatase and cholesterol sulfotransferase are regulated during late gestation in the fetal rat

Lipids in the stratum corneum (SC) are organized into lamellar membrane unit structures that provide the permeability barrier. Cholesterol sulfate, a SC membrane lipid, is synthesized by cholesterol sulfotransferase (CSTase) in the lower epidermis and hydrolyzed to cholesterol by steroid sulfatase (SSase) in the SC. To determine whether these enzymes are induced during barrier ontogenesis, we examined their activity in epidermis of fetal rats before (gestational day 17), during (day 19), and after (day 21) barrier formation. CSTase activity increased approximately 10-fold between day 17 and day 19, then declined between day 19 and day 21. In contrast, SSase activity reached its peak activity on day 21, increasing >5-fold. Fetal rat skin explants develop a SC and barrier over the same time course in vitro as in utero. Likewise, CSTase and SSase activities during in vitro ontogenesis precisely mirrored those obtained in utero. Moreover, hormones that accelerate barrier ontogenesis (e.g. glucocorticoids, thyroid hormone, and estrogen) accelerated the increase in CSTase and SSase activities during in vitro ontogenesis. mRNA levels of SSase increased in parallel with enzymatic activity, suggesting that these developmental changes are regulated at the genomic level. Finally, addition of exogenous cholesterol sulfate to explants in vitro did not accelerate either SC development or barrier formation. These studies suggest that induction of the cholesterol sulfate cycle enzymes during SC ontogenesis is a component of the fetal epidermal differentiation program and that the synthetic and degradative enzymes of this pathway are differentially regulated.

Conformation of nucleoplasmin and its interaction with DNA-protamine complex as a simple model of fish sperm nuclei

Nucleoplasmin was isolated from Xenopus laevis eggs and purified by an improved method using an open column. Its conformation was investigated spectrophotometrically by UV, CD and fluorescence. It was shown that alpha-helix content of nucleoplasmin was 30-40%, and one of the two tryptophan residues in nucleoplasmin located in the hydrophobic surroundings and the other in the relatively hydrophilic surroundings. The isolated nucleoplasmin was found to decondense sperm nuclei of salmon also, suggesting a possibility of the existence of nucleoplasmin-like protein in fish as well. Collapse of the protamine (salmine)-DNA complex as a simple model for fish sperm nuclei by nucleoplasmin was directly observed by measuring OD320 of aqueous protamine-DNA mixtures. This is a molecular level observation for the removal of protamine from DNA-protamine complex.

Primary structures of sperm-specific basic nuclear proteins and gene expression in Japanese newt, Cynops pyrrhogaster

Electrophoretic analyses of acid extracts from mature sperm of newt, Cynops pyrrhogaster, on acid/urea/Triton X-100 polyacrylamide gel showed the exclusive occurrence of sperm-specific nuclear basic proteins (SBPs), which moved faster than somatic histones on the gel. These SBPs were eluted separately by reversed phase-high-performance liquid chromatography as two large peaks and a few small peaks. Of these, only the small peaks disappeared with treatment of the acid extracts with alkaline phosphatase before they were injected into the column, so that there were only two distinct components: NP1 and NP2. Determination of amino acid sequences by the Edman method as well as by sequencing of cDNA for both components indicated that each protein consisted of 43 (NP1) or 48 (NP2) amino acid residues, rich in arginine residues (53.5% in NP1; 47.9% in NP2), forming the clusters. They had molecular masses of 5,386 Da (NP1) and 5,748 Da (NP2), respectively. Northern blot analysis using cDNAs as probes indicated that mRNAs for both NP1 and NP2 occurred not in primary spermatocytes but in round spermatids. In situ hybridization analyses using antisense RNA for NP1 as a probe clearly showed the first appearance of NP1 mRNA at the late stage of round spermatid.