Molecular cloning of POEM: a novel adhesion molecule that interacts with alpha8beta1 integrin

Cell adhesion molecules are involved in a number of biological functions, such as cell survival, cell differentiation, tissue repair, and development. A novel molecule, POEM (preosteoblast epidermal growth factor-like repeat protein with meprin, A5 protein, and receptor protein-tyrosine phosphatase mu domain), was isolated by reverse transcription-polymerase chain reaction using a set of degenerate primers designed after other known epidermal growth factor (EGF)-like motifs. From its structure, POEM was suggested to be a novel adhesion molecule with five EGF-like domains, an Arg-Gly-Asp (RGD) cell binding motif, and a meprin, A5 protein, and receptor protein-tyrosine phosphatase mu (MAM) domain. By in situ hybridization using embryonic day 16.5 (E16.5) mouse embryos, strong expression of POEM mRNA was observed in developing kidney renal tubules, parathyroid and thyroid glands, developing bone, tooth germ, and endocrine organs of the brain. The inner ear, skeletal muscle, smooth muscle (except for the vascular system), and skin were also positive for POEM expression. Bacterial recombinant POEM protein containing the RGD sequence and MAM domain showed strong cell adhesion, spreading, and survival-promoting activities. By mutating the RGD sequence to RGE, the cell spreading and survival activities were significantly decreased, but the MAM domain was shown to contribute only to cell adhesion and not to cell spreading and survival-promoting activities. The distribution of POEM in several tissues was close to that of alpha(8)beta(1) integrin. Therefore, we conducted cell adhesion assays using KA8 cells, a K562 leukemia clone stably expressing alpha(8) integrin. Parental K562 cells, which expressed alpha(5)beta(1) integrin, bound to fibronectin but not to POEM. On the other hand, KA8 cells showed strong binding and spreading on both fibronectin and POEM. These results suggest that POEM is a novel ligand for alpha(8)beta(1) integrin and that POEM may be involved in the development and function of various tissues, such as kidney, bone, muscles, and endocrine organs.

Epidemiological study on improving the QOL and oral conditions of the aged--Part 2: Relationship between tooth loss and lifestyle factors for adults men

Oral health in early- and mid-adulthood is essential for the improvement of one's QOL, this study was investigated to include an epidemiological analysis of the relationship between tooth loss and life style, such as smoking, regular exercise, and the food habits of approximately 2,000 employees. Compared with the group with mild or no periodontal disease (CPI of 0, 1, or 2), the frequency of tooth loss in the group with advanced periodontal disease (CPI of 4) was 2.00 times (odds ratio, 2.00; 95% confidence limit, 1.37 to 2.93). The probability of tooth loss showed statistical significance in relation to smoking, alcohol drinking, and frequency of meals. Compared with non-smokers, the probability that current smokers will lose teeth is 1.53 times greater (odds ratio, 1.53; 95% confidence limit, 1.20 to 1.96). It was concluded that periodontal disease and smoking must be averted for preventing tooth loss.

Epidemiological study on improving the QOL and oral conditions of the aged--Part 1: The relationship between the status of tooth preservation and QOL

In part 1 of this epidemiological study, a survey was conducted for all senior citizens aged 70 and over who resided in a mountainous village in the mid-section of Hyogo Prefecture. It focused on the relationship among the number of existing teeth, life environment, health status, and activities of daily living; and the correlation between oral status and QOL was analyzed. The daily activities of individuals were compared between those having one or more teeth and others who were totally edentulous. Subsequently, it was found that for both males and females, the odds ratio was significantly high for the dentulous individuals, in comparison with edentulous individuals, to exhibit a behavior indicative of a better QOL (such as "opportunity for conversation with family members or others)", "regular physical activities", and "attend meetings or group outings"). The result of this survey indicates that the presence of teeth is very closely related to one's daily activities. It was concluded that preventing tooth loss is vital for maintaining the masticatory function; so to prevent tooth loss, periodontal disease must be averted.

X-Serrate-1 is involved in primary neurogenesis in Xenopus laevis in a complementary manner with X-Delta-1

Notch, Delta and Serrate encode transmembrane proteins that function in cell fate specification in the Drosophila melanogaster embryo. Here we report gene expression patterns and functional characterization of a Xenopus Serrate homolog, X-Serrate-1. The isolated cDNA encoded a transmembrane protein with a Delta/Serrate/LAG-2 domain, 16 epidermal growth factor-like repeats and a cysteine-rich region. Expression of X-Serrate-1 was observed ubiquitously from unfertilized egg to tadpole, but an upregulation occurred in the tailbud stage embryo. Adult expression was found in eye, brain, kidney, heart, spleen and ovary. Whole-mount in situ hybridization revealed that the organ-related expression in eye, brain, heart and kidney occurred from an early stage of rudiment formation. Overexpression of X-Serrate-1 led to a reduction of primary neurons, whereas an intracellularly deleted form of X-Serrate-1 increased the number of primary neurons. Although the function of X-Serrate-1 in primary neurogenesis was quite similar to that of X-Delta-1, expression of X-Serrate-1 and X-Delta-1 did not affect each other. Co-injection experiments showed that wild-type X-Serrate-1 and X-Delta-1 suppressed overproduction of primary neurons induced by dominant-negative forms of X-Delta-1 and X-Serrate-1, respectively. These results suggest that X-Serrate-1 regulates the patterning of primary neurons in a complementary manner with X-Delta-1-mediated Notch signaling.

Notch signaling suppresses IgH gene expression in chicken B cells: implication in spatially restricted expression of Serrate2/Notch1 in the bursa of Fabricius

The bursa of Fabricius is a central organ for chicken B cell development and provides an essential microenvironment for expansion of the B cell pool and for generation of a diversified B cell repertoire. We report here that genes encoding the Notch family of transmembrane proteins, key regulators of cell fate determination in development, are differentially expressed in the bursa of Fabricius: Notch1 is expressed in medullary B cells located close to the basement membrane-associated epithelium (BMAE). In contrast, a Notch ligand, Serrate2, is expressed exclusively in the BMAE, which surrounds bursal medulla. A basic helix-loop-helix-type transcription factor, Hairy1, a downstream target of Notch signaling, is expressed in the bursa coordinately with Notch1 and Serrate2 and an immature B cell line, TLT1, which expresses both Notch1 and Serrate2. Furthermore, stable expression of a constitutively active form of chicken Notch1 or Notch2 in a B cell line results in a down-regulation of surface IgM expression, which is accompanied by the reduction of IgH gene transcripts. Transient reporter assay with the human IgH gene intronic enhancer reveals that an active form of Notch1 inhibits the IgH enhancer activity in chicken B cells, suggesting that Notch-mediated signals suppress the IgH gene expression via influencing the IgH intronic enhancer. These findings raise the possibility that the local activation of Notch1 in a subset of B cells by Serrate2 expressed in BMAE may influence the cell fate decision that is involved in B cell differentiation and selection inside the bursa.

Molecular cloning of delta-4, a new mouse and human Notch ligand

Complementary DNAs encoding a previously unidentified mouse Notch ligand and its human ortholog were isolated. The new Notch ligand contains a signal sequence, a DSL domain, eight epidermal growth factor-like repeats, a transmembrane domain, and an intracellular region, all of which are characteristics of members of the Delta protein family. The new protein was therefore designated Delta-4. Several previously unidentified sequences in both the extracellular and intracellular regions were shown to be conserved among vertebrate Delta proteins. The tissue distribution of Delta-4 mRNA resembles that previously described for Notch-4 (Int-3) transcripts. However, in situ hybridization with mouse lung revealed that Delta-4 mRNA is abundant in squamous alveolar cells that neighbor endothelial cells; Notch-4 expression is largely restricted to the latter cell type. Soluble forms of the extracellular portion of Delta-4 inhibit the apparent proliferation of human aortic endothelial cells, but not human pulmonary arterial endothelial cells.

Xerl: a novel secretory protein expressed in eye and brain of Xenopus embryo

A novel gene, Xerl (Xenopus EGF-like repeat with laminin-G domain protein) was isolated from a Xenopus head cDNA library prepared from tailbud. This gene encoded 779 amino acids including a potential signal sequence, twelve EGF-like repeats, a laminin-G domain, a RGD sequence and a VWF motif. In the EGF-like repeat and the laminin-G domain, Xerl showed similarity to those of Drosophila Crumbs, respectively. Zygotic expression of Xerl began at late gastrula, and increased through neurula up to the tailbud stage. In adult organs, Xerl was detected in brain and eye. Whole-mount in situ hybridization showed that Xerl expression occurred first in the anterior bilateral region of neurula and gradually localized to retina and forebrain and boundaries of midbrain and hindbrain.

Determining double-bond positions in monoenoic 2-hydroxy fatty acids of glucosylceramides by gas chromatography-mass spectrometry

We applied a gas chromatography-mass spectrometry (GC-MS) method using dimethyl disulfide (DMDS) adducts and were able to determine the double-bond positions in monounsaturated 2-hydroxy fatty acids (2-HFA). 2-HFA methyl esters, prepared from the hydrolysate of Arabidopsis thaliana leaf glucosylceramides, were acetylated and methylthiolated. GC-MS analysis of the resulting DMDS adducts showed simple mass spectra with recognizable molecular ions and a series of key fragment ions indicating the original double-bond positions in the aliphatic chain. Based on this GC-MS elucidation, we confirmed that Arabidopsis leaf glucosylceramides have C22, C23, C24, C25, and C26 chain length 2-HFA with monounsaturation, and all their double bonds are placed at the n-9 position. This procedure is simple, time efficient, and highly sensitive.

[A case of primary orbital chondrosarcoma]

The case of a twenty-year-old male with orbital chondrosarcoma is reported. He visited National Defense Medical College Hospital because of reduced vision in the right eye since two months previously. His corrected visual acuity was 8/20 in the right eye and 20/20 in the left eye. Fifteen degrees lateral displacement of the right globe and limitation of right ocular movement were recognized. Right fundus examination revealed optic disc edema and protuberant nasal fundus. Orbital computed tomography (CT) demonstrated a high density area between the inner part of the right orbit and the ethmoid sinus. Magnetic resonance imaging (MRI) showed a smoothly outlined and low intensity (T1) space occupying lesion. This lesion was irregularly enhanced by gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA). This orbital tumor was removed by an anterior approach. Histopathological examination revealed well-differentiated chondrosarcoma (grade 1) as determined by small prominent chondromatous cell projection into the collagen fibrous stroma, and existence of binucleate cells in the hypercellular region. After the operation the disc edema disappeared and his corrected right visual acuity improved to 20/20.

Antihypercholesterolemic effect of undigested fraction of soybean protein in young female volunteers

The significant antihypercholesterolemic effect of the undigested high molecular fraction (HMF) of soybean protein is known in rats, but such an effect has not been shown in humans. The present two experiments were designed to elucidate it in humans. Subjects were female university students who had relatively high serum cholesterol levels for their age. In Experiment 1, subjects took 8% of their total energy from casein, soybean protein isolate (SPI), or HMF daily for 14 days. Five basic menus and snacks were cycled. Energy intakes and daily activities were kept constant and body weight was maintained. The HMF group showed decreased low-density lipoprotein cholesterol (LDL-C) as compared to other groups. In Experiment 2, subjects took 4% of total energy from casein or HMF daily for a menstruation period. Five basic menus and snacks which contained two egg yolks (about 500 mg cholesterol) were cycled. Energy intakes and daily activities were kept constant and body weight was maintained. A decrease in LDL-C and an increase in high-density lipoprotein cholesterol (HDL-C) were observed in the HMF group as compared to the casein group. Fecal acidic steroid excretion was greater in the HMF group than in the casein group (p < 0.05). The results confirmed that HMF increases fecal steroid excretion and reduces serum cholesterol levels in humans.

Mouse alpha N-catenin: two isoforms, specific expression in the nervous system, and chromosomal localization of the gene

We isolated cDNAs encoding mouse homologues of chicken alpha N-catenin, a protein associated with the cadherin cell adhesion molecules, and identified two isoforms of this protein. One isoform (alpha N-catenin I) was identical to the chicken alpha N-catenin that had previously been identified, and the other (alpha N-catenin II) differed in having a 48-amino acid insertion in its C-terminal region. The ratio of the two isoforms changed during development; the isoform II was more abundant than the other in earlier embryonic stages, whereas isoform I was predominant in the adult stage. Immunostaining and in situ hybridization analyses revealed that the mouse alpha N-catenin was expressed almost exclusively in the nervous system. During embryogenesis, alpha N-catenin was first detected in nerve fibers of cranial and dorsal root ganglia and also in early neurons in the neural tube, including motor neurons. Thereafter, the expression of this protein occurred in various regions of the nervous system. Neurons, in general, strongly expressed alpha N-catenin, especially in their axonal fibers. On the other hand, the expression in glial cells varied with the region. For example, the ependymal layers of the neural tube generally expressed low levels of alpha N-catenin except at the inner limiting membrane facing the central canal, whereas the floor and roof plate exhibited strong expression of this protein at various portions of the central nervous system. The choroid plexus was devoid of alpha N-catenin. In the alpha N-catenin-negative regions, another subtype of alpha-catenin, alpha E-catenin, was expressed. Concerning nonneural tissues, alpha N-catenin was expressed only in some local mesenchymal cell clusters and the lens fibers. These results suggest that alpha N-catenin plays specific roles in neural cell-cell interactions. We also localized the mouse alpha N-catenin gene to chromosome 6.

Cell binding specificity of mouse R-cadherin and chromosomal mapping of the gene

R-cadherin was originally identified as a chicken cadherin expressed by the retina. Here, we describe the identification of a mouse homologue of R-cadherin. We isolated mouse cDNAs encoding a cadherin with 94% identity in amino acid sequence to the chicken R-cadherin, and defined this molecule as mouse R-cadherin. L cells transfected with the mouse R-cadherin cDNA acquired a cadherin-mediated cell-cell adhesiveness as found for other cadherins. To examine the binding specificity of mouse R-cadherin, L cells expressing this cadherin (mRL) were mixed with L cells expressing chicken R-cadherin (cRL), mouse N-cadherin (mNL), mouse E-cadherin (mEL) and mouse P-cadherin (mPL). While mRL cells randomly intermixed with cRL cells, those cells aggregated separately from mEL or mPL cells. Mixing of mRL with mNL cells gave an intermediate result; that is, they formed both separate and chimeric aggregates, suggesting that R- and N-cadherin can interact with each other although each has a preference to bind to its own type. Similar properties were previously found for chicken R-cadherin. Thus, the cell binding specificity of R-cadherin is entirely conserved between the two species, suggesting a conserved role for this protein in morphogenesis. We also located the mouse R-cadherin gene to chromosome 2.

Genomic structure and chromosomal mapping of the mouse N-cadherin gene

N-cadherin is a member of the cadherin cell-cell adhesion receptor family that includes P-, E-, and R-cadherin and liver cell adhesion molecule (L-CAM). In this study, we determined the structure of the mouse N-cadherin gene by analyzing overlapping genomic clones obtained from a mouse genomic library. This gene consists of 16 exons that disperse over greater than 200 kilobases of genomic DNA. This large size of the N-cadherin gene, compared with its cDNA (4.3 kilobases), is ascribed to the fact that the first and second introns are 34.2 kilobases and greater than 100 kilobases long, respectively. When the N-cadherin gene was compared with that of L-CAM and P-cadherin, the exon-intron boundaries were found to be fully conserved between them, except that the P-cadherin first exon includes the first and second exons of the other two genes. Also, the second intron, which is equivalent to the first intron in P-cadherin, is exceptionally large and this structural feature is conserved in all of these genes. An interesting feature of the N-cadherin gene is that this gene has an extra 16th exon that is almost identical to the other exon, 100% in the coding region and 99% in the 3' untranslated region in the nucleotide level. We also determined the chromosomal localization of the N-cadherin gene by interspecific backcross analysis and found that this gene is localized in the proximal region of mouse chromosome 18. The E- and P-cadherin genes are tightly linked and located on chromosome 8 in this species. Thus, N-cadherin is unlinked to these other cadherin loci.

Genomic organization and chromosomal mapping of the mouse P-cadherin gene

Cadherins are a family of Ca(2+)-dependent cell adhesion molecules, that includes P-cadherin, E-cadherin, N-cadherin and L-CAM. In this study, the genomic organization of the mouse P-cadherin gene was determined by analyzing overlapping DNA clones obtained from a mouse genomic library. The results showed that this gene spans over 45 kb and consists of 15 exons. A marked feature of this gene is that the first intron is 23 kbp long accounting for half its length. Comparisons of this structure with that of L-CAM, a chicken cadherin, revealed that the exon-intron boundaries are conserved between the two genes except that the P-cadherin first exon includes the correspoding first and second exons of the L-CAM gene. This gene was also similar to the other in that the second intron, which corresponds to the P-cadherin first intron, is exceptionally longer than other introns. These results suggest that the exon-intron pattern conserved in these genes is of significance for generation of domain structure of cadherin molecules or for their transcriptional regulation. We also determined the chromosomal localization of the P-cadherin gene by interspecific backcross analysis, and found that this gene is located in the central region of mouse chromosome 8 and linked with the E-cadherin locus. This is the first evidence for the linkage of different cadherin genes.

R-cadherin: a novel Ca(2+)-dependent cell-cell adhesion molecule expressed in the retina

cDNAs encoding a novel member of the cadherin cell adhesion receptor family were cloned. This cadherin is expressed in the retina of the chicken and is termed R-cadherin. It is similar to other cadherins in its primary structure, but most resembles N-cadherin, showing 74% amino acid identity. Cells expressing R-cadherin can adhere to those expressing N-cadherin when mixed, but they form homotypic clusters within their chimeric aggregates. In the development of the neural retina, R-cadherin begins to be expressed around embryonic day 8 in both neuronal and glial cells, and this expression continues up to the hatching stage. The pattern of the expression of R-cadherin was different from that of N-cadherin, suggesting distinctive roles in retinal morphogenesis.

Ectopic expression of N-cadherin perturbs histogenesis in Xenopus embryos

Xenopus embryos express N-cadherin in a pattern similar to that observed in other species, and cells expressing Xenopus N-cadherin can bind to cells expressing chicken N-cadherin in vitro. To investigate the developmental role of this molecule, we injected mRNA encoding chicken N-cadherin into one blastomere of 2-cell-stage Xenopus embryos and examined the effect of its expression on their development. The ectopic expression of N-cadherin occurred in various regions of the injected embryos and induced abnormal histogenesis, such as thickening, clumping or fusion of cell layers. These results suggest that the precise quantitative and qualitative regulation of the expression of cadherins is essential to embryonic morphogenesis.

Neural cadherin: role in selective cell-cell adhesion

Cadherins are a family of Ca2+-dependent intercellular adhesion molecules. Complementary DNAs encoding mouse neural cadherin (N-cadherin) were cloned, and the cell binding specificity of this molecule was examined. Mouse N-cadherin shows 92 percent similarity in amino acid sequence to the chicken homolog, while it shows 49 percent and 43 percent similarity to epithelial cadherin and to placental cadherin of the same species, respectively. In cell binding assays, mouse N-cadherin did not cross-react with other mouse cadherins, but it did cross-react with chicken N-cadherin. The results indicate that each cadherin type confers distinct adhesive specificities on different cells, and also that the specificity of N-cadherin is conserved between mammalian and avian cells.

The fission yeast dis2+ gene required for chromosome disjoining encodes one of two putative type 1 protein phosphatases

S. pombe dis mutants block mitotic chromosome disjunction in a manner reminiscent of aneuploidy formation, and belong to three distinct genes, dis1-dis3. We cloned two independent genomic DNAs that complemented both the cold-sensitive and caffeine-hypersensitive phenotype of dis2-11. These genes, dis2+ and a suppressor sds21+, encode proteins (calculated MW 37,000) with similar predicted amino acid sequences. dis2+ and sds21+ have overlapping functions, and disruptants are lethal only when both genes are disrupted. The gene products identified by anti-dis2 serum are enriched in nuclei. By hybridization, we obtained two cDNA clones from mouse and one genomic clone from S. cerevisiae; the latter complements S. pombe dis2-11. These dis2+ and similar polypeptides of yeasts and mouse are found to be highly homologous (75%-90% identical) to rabbit protein phosphatase 1. The implications of these findings are discussed with regard to mitotic control.

Effects of low protein intake on protein metabolism of Papua New Guinea highlanders studied with [15N]glycine

The effects of low protein intake on protein metabolism, including the size of pools and the protein synthesis rates, were studied by use of [15N]glycine in Papua New Guinea highlanders. Studies were made on 9 men between October and December in 1982. In experiment 1, two subjects were given a protein-free diet (PFD) containing 49.1 kcal/kg of energy. In experiment 2, subjects were given a sweet-potato diet (SPD) containing 45.4 kcal/kg of energy and 0.507 g/kg of protein for 8 days, and then were given a low-protein sweet-potato diet (LPSPD) containing 50.0 kcal/kg of energy and 0.265 g/kg of protein. During the SPD period, the sizes of the metabolic and active protein pools (mean +/- SD) were 270 +/- 134 mgN/kg and 362 +/- 107 mgN/kg, respectively, and the rates of active and inactive protein synthesis were 463 +/- 161 mgN/kg/day and 299 +/- 38 mgN/kg/day, respectively. During the LPSPD period, the sizes of the metabolic pool and active protein pool were 131 +/- 64 mgN/kg and 378 +/- 106 mgN/kg, respectively, and the rates of active and inactive protein synthesis were 490 +/- 206 mgN/kg/day and 280 +/- 26 mgN/kg/day, respectively. The protein metabolism in the LPSPD showed no significant difference from the SPD. The results suggest that, when the energy levels were approximately the same, protein metabolism in Papua New Guinea highlanders was maintained in spite of the decrease in protein intake.

Responses of sodium balance, blood pressure, and other variables to sodium loading in Papua New Guinea highlanders

For determination of the responses of sodium balance, blood pressure, and other relevant variables to Na loading in people with a low intake of Na, 10 male Papua New Guinea highland subjects were given additional Na at two levels (128 and 256 mmol/d) for 10 d after a 3-d control period of low-Na diet. Na loading caused a marked positive balance of Na, decreases of aldosterone concentration and renin activity in the plasma, and a decrease of urinary aldosterone excretion. The blood pressure, particularly that measured at noon, increased in the latter half of the Na-loading period, the increase being significant in the group given 256 mmol of sodium daily: the systolic and diastolic blood pressure increased from 92 +/- 8 over 56 +/- 7 mm Hg in the control period to 102 +/- 7 over 60 +/- 4 mm Hg in the latter half of the test period (p less than 0.05).

Synthesis and degradation of collagens in skin of healthy and protein-malnourished rats in vivo, studied by 18O2 labelling

To explore the effects of growth retardation, caused by restricted protein intake, on collagen turnover in the whole skin, Sprague-Dawley rats (n = 20) were labelled with 18O2 and fed on either an adequate (18%) or a low (3%) lactalbumin diet. Skin biopsies were obtained at intervals during the following 6 months. Independent groups of animals (n = 186) were used to determine the size of the 0.5 M-acetic acid-soluble and -insoluble collagen pools in the entire skin of healthy and malnourished rats. Collagen was estimated by measurement of hydroxyproline. Soluble-collagen synthesis rates were equivalent to 99 +/- 8 mumol of hydroxyproline/day in healthy animals and 11 +/- 2 mumol/day in malnourished rats. Insoluble-collagen synthesis rates were 32 and 5 mumol of hydroxyproline/day in the healthy and protein-depleted rats respectively. The degradation of soluble collagen amounted to 37 +/- 8 and 6 +/- 2 mumol of hydroxyproline/day in the healthy and malnourished groups respectively. Efflux of collagen from the soluble collagen, defined as the sum of the rate of soluble collagen that is degraded plus that which matures into insoluble collagen, was 70 +/- 8 and 11 +/- 2 mumol of hydroxyproline/day in the healthy and malnourished groups respectively. Insoluble collagen was not degraded in either group. The fraction of soluble collagen leaving the pool that was converted into insoluble collagen was 0.46 in both diet groups. It is concluded that the turnover of soluble collagen is markedly decreased with malnutrition, but degradation and conversion into insoluble collagen account for the same proportions of efflux from the soluble-collagen pool as in rapidly growing rats.

Stage-specific keratins in Xenopus laevis embryos and tadpoles: the XK81 gene family

This report describes the isolation and characterization of genomic and cDNA clones which define a subfamily of type I keratins in Xenopus laevis whose expression is restricted to embryonic and larval stages. The XK81 subfamily, named after the prototype cDNA clone DG81, contains four members arranged in two pairs of closely homologous loci; they were named 81A1, A2, B1, and B2. Genomic clones were obtained representing all of these regions. The A1 gene has been completely sequenced together with approximately 1 kb of flanking sequences at each end; this gene corresponds to the previously reported cDNA clone 8128 (Jonas, E., T. D. Sargent, and I. B. Dawid, 1985, Proc. Natl. Acad. Sci. USA, 82:5413-5417). The B2 gene is represented by a partial cDNA clone, DG118. Upstream sequences and about half of the coding regions have been sequenced for the B1 and B2 genes, whereas the A2 locus has been identified on the basis of hybridization data and could be a gene or pseudogene. Genomic Southern blotting indicates that all members of the subfamily have been isolated. The keratin proteins encoded by the B1 and B2 genes are 96% homologous in the central rod domain, whereas A/B gene homology in this region is 81%. During development mRNAs derived from A and B genes accumulate coordinately during gastrula and neurula stages; in the tadpole, 81A mRNA decays rapidly, whereas 81B mRNA shows a second abundance peak, persists for most of tadpole life, and decays by metamorphosis. RNAs derived from the XK81 keratin subfamily are undetectable in the adult, where different type I keratin genes are expressed.

Closed-circuit metabolic system with multiple applications

A closed-circuit metabolic system has been designed and tested for multiple applications. Air pressure within a closed chamber is regulated electronically while allowing for respiratory gas exchange. Compared with a previously reported standard indirect calorimetry system, the new device had by virtue of longer duration of measurement improved precision (coefficient of variation 3% vs. 14%) during studies of O2 consumption both at room temperature and at 5 degrees C. In addition, a more physiological atmospheric environment is maintained. This system has also been utilized for simultaneously labeling groups of up to 20 weanling rats with 18O2 over a 2-day period and for exposure of rats to a hyperoxic (84% O2), normobaric environment for 4-day periods. Potential applications include maintenance of pressure (hypobaric through hyperbaric) and O2 (hypoxic through hyperoxic) controlled environments, exposure to toxic gases, study of diurnal variations in metabolic rate, measurement of metabolic expenditure with activity, and adaptation to other species including humans.

Studies of nitrogen balance in male highlanders in Papua New Guinea

Nitrogen metabolism in Papua New Guinea highlanders was studied by examining their nitrogen balance when they ate their usual diet (experiment 1) or an experimental diet (experiment 2). Studies were made on 39 male highlanders between October and December in 1980 and 1982. In experiment 1, the average protein and energy intakes (mean +/- SD) for three consecutive days of usual diets were 116.2 +/- 31.2 mg N/kg body weight and 46.9 +/- 8.9 kcal/kg body weight in 1980 and 143.5 +/- 54.8 mg N/kg body weight and 47.3 +/- 10.5 kcal/kg body weight in 1982, and thus the nitrogen balances were 27.7 +/- 28.3 and 18.4 +/- 24.2 mg N/kg body weight, respectively. Most dietary protein and energy was derived from sweet potatoes and other vegetable foods, but between 1980 and 1982 the diet changed slightly with increased consumption of imported foods such as rice and canned fish. In the second experiment, when 10 highlanders were given adequate protein diet (about 200 mg N/kg body weight and about 44 kcal total energy/kg body weight for 13 d, much of the dietary nitrogen was retained in their bodies (45.1 +/- 19.3 mg N/kg body weight). When another group of men were fed a sweet-potato diet (81.1 mg N/kg body weight for 8 d followed by a low protein sweet-potato diet containing only 42 mg N/kg body weight with 50 kcal/kg body weight for 14 d, nitrogen true digestibility and net protein utilization increased and their nitrogen balance showed no significant change (-11.0 +/- 5.6 mg N/kg body weight).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary protein levels on urea utilization in Papua New Guinea highlanders

Ability to utilize urea nitrogen for body protein synthesis was examined with Papua New Guinea (PNG) highlanders and Japanese (JPN). Eight male PNG highlanders and 8 male JPN were fed on a low protein diet containing 0.55 g protein/kg or an adequate protein diet containing 1.34 g protein/kg for 1 or 2 weeks. The fate of 15N was measured after oral administration of 15N-labelled urea. There was no difference in 15N incorporation into serum protein between PNG highlanders and JPN receiving low protein diets. On the other hand, on the adequate protein diet, 15N incorporation in PNG highlanders was similar to that on the low protein diet, in contrast to that in JPN which was hardly detected in the adequate protein diet. When PNG highlanders take more protein than protein in their usual diet, they effectively incorporate ingested protein into their body protein and urea nitrogen is utilized for synthesis of body protein.

Gene expression in Xenopus embryogenesis

This article considers some aspects of the storage of macromolecules in the oocyte of Xenopus laevis and the activation of previously unexpressed genes during early embryogenesis. The large quantity and complex nature of poly(A)+ RNA accumulated in the egg provides the cleavage embryo with a supply of mRNA sufficient to sustain protein synthesis for several hours of development. Onset of gene activity at the midblastula transition (MBT) leads to the synthesis and accumulation of molecules of various RNA classes, including tRNAs, rRNAs, mRNAs and mitochondrial RNAs. At gastrulation the poly(A)+ RNA population is still qualitatively similar to that of the egg but some sequences not present in egg RNA have accumulated by this time. Through the use of a subtractive cDNA cloning procedure we have prepared a library of sequences that represent genes activated for the first time between MBT and gastrula. A study of several of these cDNA clones suggests that genes in this class are restricted in their activity to embryonic and tadpole stages.

Blood status and serum free amino acids in Papua New Guinea highlanders

Hematological values and serum amino-acid concentrations were measured in 17 healthy male adult Papua New Guinea highlanders who live on a sweet-potato staple diet. Hematological values were within the normal range, except for a low serum urea concentration. The concentrations of serum threonine, valine, isoleucine, leucine and tyrosine were significantly lower, and those of arginine, glutamate, glycine and alanine were significantly higher, than in Japanese controls. These amino acid patterns in the serum of Papua New Guinea highlanders are an indication of low protein nutrition and adequate energy supply. Some essential amino acid and urea concentrations in the serum of nine Papua New Guinea subjects fed on an adequate protein diet (1.3 g/kg body weight, about twice their habitual diet) for 13 days were significantly increased but were still significantly lower than those of Japanese subjects. Serum alanine decreased on an adequate protein diet. These results show that amino acid uptake and utilization by peripheral tissues may be accelerated on an adequate protein diet. Blood status and serum amino acid concentrations did not show any change except for urea and some amino acids, when five Papua New Guinea highlanders were fed on a low protein diet (0.6 g/kg) consecutively for 13 days.

Endogenous nitrogen excretion in male highlanders of Papua New Guinea

Endogenous nitrogen excretion was examined in highlanders of Papua New Guinea. Eight highlanders were fed a semisynthetic protein-free diet with about 49 kcal/kg of energy for 11 days. At the end of this period they excreted 29.2 +/- 4.0 mg N/kg of urinary nitrogen and 13.9 +/- 2.5 mg N/kg of fecal nitrogen per day. When the values were expressed per basal metabolic rate (BMR), they were 1.25 +/- 0.19 mg N/kcal BMR for urine and 0.59 +/- 0.08 mg N/kcal BMR for feces. The total amount was calculated as 43.1 +/- 4.3 mg N/kg (1.84 +/- 0.18 mg N/kcal BMR). Endogenous urinary nitrogen excretion in highlanders was the lowest so far reported; the effects of ethnic and nutritional backgrounds on obligatory urinary N loss were examined but no clear explanation was found for the highlanders' low value.

Structural analysis of antigen-specific Ia-bearing regulatory T-cell factors: gel electrophoretic analysis of the antigen-specific augmenting T -cell factor

An antigen-specific T-cell factor (TaF) that specifically augments the antibody response was purified and biochemically analyzed by NaDodSO4/polyacrylamide gel electrophoresis and isoelectric focusing. Biosynthetically labeled TaF was separated from the Nonidet P-40 extract of T-cell hybridoma FL10, which produces a keyhole limpet hemocyanin-specific TaF, by affinity chromatography either with antigen or with monoclonal anti-I-A antibodies. The material thus obtained was composed of two different types of molecules of molecular weights of 67,000 and 33,000 under nonreducing conditions. After reduction with dithiothreitol, all the molecules migrated to the position of molecular weight 33,000. The absorption studies with immunoadsorbents of antigen and antibodies revealed that the intact TaF is a heterodimer of two discrete polypeptide chains, one carrying a determinant detectable by a monoclonal anti-Tindd directed to an Igh-I -linked allotypic structure of T cells and being associated with the antigen-binding site and the other expressing a unique determinant controlled by the I-A subregion of murine H-2 major histocompatibility complex but being different from known class II polypeptide chains. The antigen-binding polypeptide has an isoelectric point of pH 5.6, and the I-A polypeptide has an isoelectric point of pH 6.3.

Unique T cell Ia antigen expressed on a hybrid cell line producing antigen-specific augmenting T cell factor

Hybrid cell lines were established by fusion between keyhole limpet hemocyanin(KLH) binding T cells of A/J mice and an AKR T cell tumor line, BW5147. Hybrids were selected for the presence of Ia antigen and KLH-specific augmenting activity of their extracts in the secondary antibody response. The detailed phenotypic and functional analysis of 1 of these clones, FL10, is reported here. The hybrid was positive for both Thy1.1 and Thy1.2 antigens and possessed the Lyt-1+,2-,3- phenotype. Both VH and Ia determinants were detected on their cell surface. The IA locus was mapped in the I-A subregion, but the Ia specificities were serologically distinct from those of B cell Ia antigen. This was demonstrated by the fact that anti-Ia antiserum preabsorbed with B cells could react with the hybrid cells, whereas none of the monoclonal anti-Ia specific for private and public determinations of Iak could. The extract from the cell line specifically augmented the in vitro secondary antibody response against dinitrophenylated KLH, and this activity was removed by absorption with antigen and conventional anti-Ia antisera. The results indicate that the cell line, FL10, carries Ia antigen unique to the T cell, which is associated with the antigen-specific augmenting molecule.

Unique T cell Ia antigen expressed on a hybrid cell line producing antigen-specific augmenting T cell factor

Hybrid cell lines were established by fusion between keyhole limpet hemocyanin(KLH) binding T cells of A/J mice and an AKR T cell tumor line, BW5147. Hybrids were selected for the presence of Ia antigen and KLH-specific augmenting activity of their extracts in the secondary antibody response. The detailed phenotypic and functional analysis of 1 of these clones, FL10, is reported here. The hybrid was positive for both Thy1.1 and Thy1.2 antigens and possessed the Lyt-1+,2-,3- phenotype. Both VH and Ia determinants were detected on their cell surface. The IA locus was mapped in the I-A subregion, but the Ia specificities were serologically distinct from those of B cell Ia antigen. This was demonstrated by the fact that anti-Ia antiserum preabsorbed with B cells could react with the hybrid cells, whereas none of the monoclonal anti-Ia specific for private and public determinations of Iak could. The extract from the cell line specifically augmented the in vitro secondary antibody response against dinitrophenylated KLH, and this activity was removed by absorption with antigen and conventional anti-Ia antisera. The results indicate that the cell line, FL10, carries Ia antigen unique to the T cell, which is associated with the antigen-specific augmenting molecule.

Photochemical studies of 7-cis-rhodopsin at low temperatures. Nature and properties of the bathointermediate

The photoreaction of 7-cis-rhodopsin derived from 7-cis-retinal and cattle opsin was studied by low-temperature spectrophotometry. Upon irradiation of 7-cis-rhodopsin at liquid nitrogen temperature (-190 degrees C) with blue light, its spectrum shifted to the longer wavelengths, indicating the formation of a bathoproduct. The bathoproduct thus formed was found to be identical with bathorhodopsin formed from rhodopsin in their spectroscopic, photochemical, and thermal properties. Therefore, we believe that the bathoproduct is, in fact, bathorhodopsin. The fact that 7-cis-rhodopsin can be readily converted to rhodopsin and to 9-cis-rhodopsin shows that the identical retinal binding site of opsin is involved in the three isomeric rhodopsins. These results appear to be consistent with the notion that the chromophore of bathorhodopsin is a twisted all-trans isomer, which is readily obtainable from the 7-cis, 9-cis, and 11-cis isomers.

Requirement and utilization of egg protein by Japanese young men with marginal intakes of energy

The effect of marginal intakes of energy on the requirement and utilization of egg protein was evaluated in 46 Japanese young men. The subjects were given a standard diet for 1 week and then low protein diets for 2 weeks. These diets contained about 32, 64, and 80 mgN/kg with whole eggs as the protein source. In the first experiment with excess energy, the energy intakes of 31 subjects were kept constant during the 3 week experiment, the mean intakes being 48.2 +/- 1.5 kcal/kg. The body weight was affected by changing protein intakes while maintaining energy intakes at 48 kcal/kg. From regression analysis, the N requirement for apparent N equilibrium was estimated to be 82.0 +/- 8.0 mgN/kg, where NPU was calculated as 56. In the second experiment with submaintenance energy, 15 subjects received 40 kcal/kg. The N requirement was 124 +/- 21 mgN/kg, where NPU was calculated as 37. From these results and those of previous studies, it was concluded as follows: 1) N balance and NPU were remarkably affected by energy intake changed around maintenance level; and 2) the NPU for egg protein in young men for maintenance intakes of energy and N is about 50 to 55. For estimation of the protein requirement for Japanese adults, a correction factor of 100/55 (about 1.8) was used instead of 1.3 adopted by the 1973 FAO/WHO.

Nutritive efficiencies of lactalbumin and wheat gluten at very low levels of intake in adult rats

The nutritive values of proteins in relation to their intake levels were evaluated by feeding adult male rats weighing 250 g diets containing 0%, 0.39%, 0.78%, 1.56%, 2.34%, 3.90%, 7.79% and 15.58% lactalbumin or wheat gluten for three weeks. The biological values (BV) of both proteins were high at low levels of protein intake but decreased with increase in protein intake. The BV of wheat gluten was estimated to be about 100 at a level of intake of 1.56% but only 25 at a level of 15.58%. Similarly, the BV of lactalbumin decreased with increase in the protein level, being 67 at a level of 7.79%. The BVs of both proteins at low levels of dietary protein (below 2.34% of lactalbumin or 0.78% of wheat gluten) were apparently more than 100 because urinary N excretion was less than endogenous N. The BVs also decreased with time during the three-week test period. It is concluded that BV of a protein is not a fixed value but varies with the experimental conditions especially with changes in the amount of intake, and that differences in the qualities of various proteins cannot be compared quantitatively at a single level of protein. The results were briefly discussed in relation to protein requirements.