A new mutation Rim3 resembling Re den is mapped close to retinoic acid receptor alpha (Rara) gene on mouse Chromosome 11

A new mouse mutation, recombination-induced mutation 3 (Rim3), arose spontaneously in our mouse facility. This mutation exhibits corneal opacity as well as abnormal skin and hair development resembling rex denuded (Re ^den ) and bareskin (Bsk). Large-scale linkage analysis with two kinds of intersubspecific backcrosses revealed that Rim3 is mapped to the distal portion of Chromosome (Chr) 11, in which Re ^den and Bsk have been located, and is very close to the retinoic acid receptor, alpha (Rara). The genes, keratin gene complex-1, acidic, gene 10, 12 (Krt1-10, 12), granulin (Grn), junctional plakoglobin (Jup) and Rara, all of which regulate growth and differentiation of epithelial cells, are genetically excluded as candidate genes for Rim3, but are clustered in the short segment on mouse Chr 11. Received: 3 July 1997 / Accepted: 26 August 1997     

Morphological evaluation of microvascular networks and angiogenic factors in the selective growth of oocytes and follicles in the ovaries of mouse fetuses and newborns

In the mammalian ovary, there is a striking difference in the distribution of blood vessels to individual follicles, suggesting that a microvascular network affects the selective growth of oocytes and follicles. In the present study the role of microvascular networks and angiogenic factors on the selective growth of oocytes and follicles was evaluated histologically in fetuses and newborns of ICR strain mice. Apparent selective growth of oocytes and follicles was observed in the ovaries of 1 day old newborns and, at this time, microvascular networks were recognized electronmicroscopically around the follicle that had completed the formation of its follicular structure and contained oocytes more than about 20 μm in diameter. In 3 day old newborns, oocytes more than 30 μm in diameter were detected where blood capillaries were well vascularized. Immunoreactivity to epidermal growth factor (EGF) and a strongly negative charged (colloidal iron-positive) substance (glycosaminoglycans; GAG), which have angiogenic activity, were detected in the ovaries of 3 day or older newborns and were identified more often around growing follicles containing oocytes more than 30 (GAG) and 40 (EGF) μm in diameter. Ovaries removed from 20 day old fetuses and cultured for 4 and 6 days in vitro showed a different distribution of growing follicles. A proportion of oocytes 20.0–24.9 μm in diameter increased during 4 and 6 days of incubation. However, the majority of oocytes did not grow further. These findings indicate that microvascular networks and angiogenic factors are deeply involved in selective oocyte growth beyond approximately 20–30 μm in diameter in mouse ovaries.     

Synthesis, intestinal absorption and metabolism of sarcosine conjugated ursodeoxycholic acid

Sarcosine conjugated ursodeoxycholic acid (SUDC) was synthesized and its intestinal absorption and metabolism were studied in rat and hamster. Intestinal absorption study using bile fistula rat shows that more than 90% of SUDC administered intraduodenally was excreted in the bile within 24 hr. No change of the administered bile acid was seen during the absorption from the intestine, the passage of the liver, and the excretion into the bile. When [24-14C]SUDC and [11,12-3H2]-ursodeoxycholic acid were administered orally to a hamster, more than 95% of both the administered 14C and 3H were recovered from the feces within 6 days. Most (77%) of the fecal 14C-labeled compound was SUDC, whereas 95% of the fecal 3H-labeled compound was unconjugated lithocholic acid. These results indicate that SUDC, unlike taurine or glycine conjugated bile acid, resists bacterial deconjugation and 7-dehydroxylation.     

Reconstruction of the skin in three-dimensional collagen gel matrix culture

Summary The skin comprises three layers: epidermis, dermis, and hypodermis. We report here on a skin, reconstructed in vitro, that is composed of all three layers. The topmost layer, epidermis, was exposed to air by a new method. The exposure induced an extensive proliferation, and differentiation, i.e. keratinization was eventually observed in the cultured epidermal cells. Skin thus cultured will be a useful graft of transplantation and provide an ideal model system in which to study diseases of the skin.     

Correlation between Biosynthesis of Chlorogenic Acid and Flowering in Asparagus Seedlings Induced by Carbamate Compounds

The flowering of Asparagus seedlings induced by carbamate compoundswe had developed was triggered when the chemicals were appliedin such a way that they were active during the period of shootdifferentiation, i.e., 4 to 10 days after seeding. The rateof flowering was closely correlated to the decrease in the chlorogenicacid content of the bud primordium caused by the carbamate treatment.Cytokinins stimulated metabolism in the buds and decreased theinhibitory effect of the carbamates on it. The site of actionof the chemicals appears to be somewhere on the metabolic pathwaythat leads to the synthesis of chlorogenic acid. (Received August 2, 1990; Accepted February 14, 1991)     

Identification of rat cDNA encoding hck tyrosine kinase from megakaryocytes.

A rat homologue of hck tyrosine kinase cDNA from a rat megakaryocyte library contains 1911 nucleotides with an open reading frame encoding 503 amino acids. The rat hck had distinct amino acid residues from the mouse homologue exhibiting 97.6% identity. The sequence contains the SH2 and SH3 regions that interact with cytoplasmic signaling proteins, the kinase domain including the nucleotide binding site and the autophosphorylation site, and the C-terminal Tyr-499 known as a negative regulator.     

The fine structure of the bovine Descemet's membrane with special reference to biochemical nature

Summary A freeze-etch replica method combined with biochemical analyses was used to investigate the ultrastructural organization of the bovine Descemet's membrane.The freeze-etch replica observations revealed that the intact Descemet's membranes were composed of stacks of two-dimensionally arranged hexagonal lattices, in which four components were resolved; (1) round densities as nodes, (2) rod-like structures connecting the densities, (3) randomly oriented fine filaments within the lattices, and (4) amorphous materials covering the lattices.When the membranes were treated with sodium dodecyl sulfate (SDS) and mercaptoethanol, only the amorphous materials were solubilized. However, both the amorphous materials and rod-like structures disappeared in SDS-mercaptoethanol-urea-treated membranes. When the membranes were treated with a very low concentration (0.0005%) of collagenase, rod-like structures and round densities remained insoluble. If the concentration was raised to 0.01%, only the round densities persisted.Comparing these data with the amino acid analysis of each fraction, the following conclusions may be drawn: rod-like structures and fine filaments contain collagenous proteins of different solubility, while round densities and amorphous materials are non-collagenous in nature.     

Dark-field light microscopic study of the flexibility of F-actin complexes

The flexibility of F-actin complexed with saturating amounts of myosin subfragments has been measured by the use of a dark-field light microscope and a high-sensitivity television camera. When dilute solutions of F-actin complexes were observed in the microscope, single filaments in flexural thermal motion were visible to the eye. Images of the fluctuating filaments were recorded on videotapes using the high-sensitivity camera, and these records were used for the analysis of fluctuation to calculate flexibility in the framework of statistical mechanics of thermal fluctuation in semi-flexible rods. The analysis was carried out by two different methods. In method A, we selected many filaments (the entire length appeared near focus occasionally in the limited period of 10 to 100 seconds), measured the mean square end-to-end distance 〈R²〉 of each filament during the period and also its contour length L, and calculated a parameter λ representing flexibility by the equation given by Landau & Lifshitz (1958): $\text{〈R}{}^2\text{〉 =}\text{[2λL ? 1 +}\text{exp}\text{(?2λL)]}\text{2λ}{}^2$. Then, we obtained a value for λ = 0.040 ± 0.010 μm^?1 for the acto-heavy meromyosin filament at 24.0 °C ± 1.0 deg. C, and λ = 0.027 ± 0.005 μm^?1 for the acto-tropomyosin-heavy meromyosin filament at the same temperature.In method B, still photographs were taken of the video screen to collect a great number of filaments or parts of filaments which appeared just in focus over their length, and the contour length L of each filament and the angle θ(L) between the tangents at its two ends were measured, on the basis of the assumption that the whole length of each filament was in a plane perpendicular to the direction of view. The data were treated statistically and the results were approximated with 〈cosθ(L)〉 = exp(?λL), which holds for an ensemble of filaments with flexibility λ but in two-dimensional thermal motion (Landau & Lifshitz, 1958). The λ-values obtained by this method for acto-heavy meromyosin and acto-tropomyosin-heavy meromyosin filaments were both in good agreements with those obtained by method A, confirming the reliability of our measurement.F-actin complexed with a saturating amount of myosin subfragment-1 was examined by method B, and its flexibility was shown to be little different from that of acto-heavy meromyosin filaments.