Direct sequencing of tobacco chloroplast genome by the polymerase chain reaction

We have developed a polymerase chain reaction (PCR) method for sequencing of tobacco chloroplast genome. In a mixture containing chloroplast DNA, 5'-end-labeled oligonucleotide primer, Taq DNA polymerase and reaction buffer, we were able to sequence a segment of chloroplast 16S rRNA gene. The results showed that the 750 bp of DNA sequenced were identical to the sequence reported, indicating that direct sequencing method that we have developed is useful for the sequencing of chloroplast genome. To analyze the chloroplast genome more rapidly in those in vitro grown plantlets, we also developed a simple method which is applicable for the amplifications and sequencing of chloroplast 16S rRNA fragment from either 0.15 g of tobacco leaf or stem tissue. The readable sequences obtained from the presented methods were consistent with the published sequence.

Cigarette smoking and other risk factors for progression of precancerous stomach lesions

BACKGROUND

Stomach cancer is generally thought to evolve through a series of gastric mucosal changes, but the determinants of the precancerous lesions are not well understood.

PURPOSE

Our purpose was to assess risk factors for intestinal metaplasia and gastric dysplasia arising from chronic atrophic gastritis in a general population at high risk for stomach cancer.

METHODS

A population-based gastroscopic screening of more than 3000 residents was conducted in a county in China with one of the world's highest rates of stomach cancer. Information on the lifestyle and other characteristics of the participants was obtained by interview, and responses were compared between those in whom the most advanced gastric lesion was dysplasia or intestinal metaplasia versus those with chronic atrophic gastritis.

RESULTS

Cigarette smoking was found to nearly double the risk of transition to dysplasia and to be a mild risk factor for intestinal metaplasia. Smoking accounted almost entirely for the 55% higher prevalence of dysplasia among men than among women. Risk of transition to dysplasia had a weak association with several dietary factors and was increased among those participants with a family history of stomach cancer and with blood type A.

CONCLUSIONS

The findings provide strong evidence for a role of tobacco consumption and offer clues to other environmental and genetic factors involved in the process of gastric carcinogenesis.

Estimating the potential of sugarcane families to produce elite genotypes using univariate cross prediction methods

A quick, accurate method to determine the potential of a sugarcane (Saccharum spp.) cross to produce elite progeny is needed for maximizing genetic gain. Development of a practical cross appraisal method was initiated by evaluating 1,800 progeny from 15 crosses among 23 parents at two intrarow plant spacings (41 cm and 82 cm). Plant spacing was examined for its affect on stool weight variability. The goals were to identify the most reliable and/or easily obtained cross appraisal statistic and to determine the earliest breeding program stage and crop to collect these statistics. Three tests, on plant cane (PC) and first ratoon (FR) single stool seedlings and clonal plant cane plots, were conducted. Four statistics, the family mean, the estimated elite proportion (PROB), the observed elite proportion, and the best linear unbiased predictor (BLUP) were estimated and examined for each cross. These statistics were strongly correlated within each test (0.69≤r≤1.00). Family worth estimates based on single stool data were moderately correlated (ca. range 0.5≤r≤0.7) to the family worth estimates based on clonal plots.The research suggested that the potential of a cross to produce elite progeny for a trait could be accurately predicted by the cross mean of that trait. Data for the mean were the most easily obtained and, hence, would be the most practical family appraisal statistic to use in a breeding program. Correlations of statistics among the PC and FR seedlings and the clonal plots showed that the PC estimates of Brix, stalk weight, and its components, stalk length and stalk diameter, could be used for cross appraisal. Genotypic selection by the Louisiana Sugarcane Variety Development Program (LSVDP) occurs among the FR seedlings. FR stalk number and PC Brix and stalk weight data could be used to perform family selection prior to the currently practiced individual plant selection. The benefits of family selection to the LSVDP were demonstrated by the expected genetic gains for two selection scenarios. The gains were consistently larger for an initial 50% family selection and subsequent 20% individual selection than they were for simple individual selection at a 10% selection intensity. Our research also suggests that the use of a wider intrarow spacing may improve the ability to discern among seedlings due to its enhancement of stool weight variability.

Molecular cloning of silver carp and bighead carp prolactin

The cDNAs encoding the prolactin of silver carp (scPRL) and bighead carp (bcPRL) have been cloned. Deduced from the nucleotide sequences, both scPRL and bcPRL are composed of 187 amino acid residues. Only one residue is different between scPRL and bcPRL. Homology analysis indicates that scPRL and bcPRL are highly homologous to carp PRL (97%), relatively conserved in relation to PRLs of salmon, trout, and tilapia (64-69%), and diversified from avian and mammalian PRL (30-35%). Similar to PRLs of other species of fish, scPRL and bcPRL lack the first 12 N-terminal residues of avian and mammalian PRLs.

Estimating the potential of sugarcane families to produce elite genotypes using bivariate prediction methods

Three bivariate statistical methods to predict the family potential to produce elite progeny were studied to improve the efficiency of a sugarcane (Saccharum spp.) breeding program. Progeny from 15 piparental crosses were evaluated in plant cane and first ratoon seedlings, and in clonal plant cane plots during 1989 and 1990. The bivariate predictions of Brix combined with cane yield components (stalk number, stalk weight, stalk diameter, stalk length, and stool weight) were investigated. The best linear unbiased predictors (BLUPs) and the sum of ranks based on family mean values of two traits (RANK) were repeatable among tests in the estimation of family potential. Bivariate normal probabilities (PROB) estimated with family means, phenotypic standard deviations, and genetic correlations generally demonstrated poor repeatability among tests. The three statistical predictions were compared with the progeny selection rate within the crosses through three selection stages. Predictions were not correlated to the selection rates of eight crosses with smaller initial progeny populations (< 500 progeny). However, when the predictions were compared with the 7 of 15 families over which 1,000 progeny for each cross had been evaluated, the rankings based on BLUP and RANK bivariate predictions of Brix and stool weight identified the better crosses. PROB was inconsistent in this regard. Early selection work is highly subjective. We speculate that near-random selection occurs for stalk number at the initial selection stage and that the high selection rate at this stage (≈5%) generates a first clonal population (10 to 25) that is too small to accurately base selection rates for stalk number. Larger initial progeny populations produce sufficiently large clonal populations (>50) to appraise crosses using selection rates. The study suggested that family evaluations for breeding programs can use bivariate predictions. The comparative ease of calculating the RANK estimate versus the BLUP along with the absence of any apparent loss of predictive value suggests that the RANK method would be the most suitable statistic to use for bivariate predictions.

Chromosomal assignments of mouse connexin genes, coding for gap junctional proteins, by somatic cell hybridization

The connexin genes Cx31 and Cx45 coding for proteins of gap junctional subunits have been assigned to mouse chromosomes 4 and 11 by Southern blot hybridization of specific gene probes to DNA from mouse x Chinese hamster somatic cell hybrids. In addition, our results confirm the recent assignment of mouse connexin genes Cx26, Cx32, Cx37, Cx40, Cx43, and Cx46 to mouse chromosomes 14, X, 4, 3, 10, and 14, respectively, by analysis of interspecific backcrosses and by somatic cell hybridization. Our assignment of the Cx31 gene to mouse chromosome 4 locates the fourth connexin gene on this mouse chromosome to which the genes for Cx31.1, Cx37, and Cx30.3 have previously been assigned. Interestingly three of them (coding for Cx31, Cx31.1, and Cx30.3) are preferentially expressed in skin. Possibly some of the connexin genes clustered on mouse chromosome 4 may be regulated coordinately.

Distribution of type A and type B EBV in normal individuals and patients with head and neck carcinomas in Taiwan

The subtypes of Epstein-Barr virus (EBV) according to the EBNA 2 gene were investigated in Taiwan by the polymerase chain reaction (PCR) and by Southern blot hybridization. The materials included 53 nasopharyngeal carcinoma (NPC) biopsies, 49 other head and neck cancers and 32 throat washings of normal individuals. EBV DNA was found in all NPC biopsies, 27 of 49 other head and neck carcinomas and 81% of normal individuals. Type A EBV was the predominant type of EBV in both normal individuals and patients with head and neck carcinomas in Taiwan. Type B EBV or coexistence of the A and B types comprised a small number of samples in this study.

Peptidoglycan composition of a highly methicillin-resistant Staphylococcus aureus strain. The role of penicillin binding protein 2A

All clinical isolates of methicillin-resistant Staphylococcus aureus contain an extra penicillin binding protein (PBP) 2A in addition to four PBPs present in all staphylococcal strains. This extra PBP is thought to be a transpeptidase essential for the continued cell wall synthesis and growth in the presence of beta-lactam antibiotics. As an approach of testing this hypothesis we compared the muropeptide composition of cell walls of a highly methicillin-resistant S. aureus strain containing PBP2A and its isogenic Tn551 derivative with reduced methicillin resistance, which contained no PBP2A because of the insertional inactivation of the PBP2A gene. Purified cell walls were hydrolyzed into muropeptides which were subsequently resolved by reversed-phase high-performance liquid chromatography and identified by chemical and mass spectrometric analysis. The peptidoglycan composition of the two strains were identical. Both peptidoglycans were highly cross-linked mainly through pentaglycine cross-bridges, although other, chemically distinct peptide cross-bridges were also present including mono-, tri-, and tetraglycine; alanine; and alanyl-tetraglycine. Our experiments provided no experimental data for a unique transpeptidase activity associated with PBP2A.

Peptidoglycan composition in heterogeneous Tn551 mutants of a methicillin-resistant Staphylococcus aureus strain

It was shown that Tn551 inactivation of two chromosomal (so-called auxiliary) loci other than the mec gene result in a dramatic reduction of methicillin resistance and decreased cell wall turnover and autolytic capacity in a methicillin-resistant Staphylococcus aureus strain (de Jonge, B. L. M., de Lencastre, H., and Tomasz, A. (1990) J. Bacteriol. 173, 1105-1110). To understand the mechanistic basis of these phenomena we have examined the status of the autolytic enzymes and the muropeptide composition of peptidoglycan using reversed-phase high-performance liquid chromatography and mass spectral analyses. While no differences could be detected in the number of autolytic hydrolases, the mutants showed major changes in peptidoglycan composition. Nine prominent muropeptides of the parental strain each carrying a pentaglycyl substituent were missing from the cell wall of one group of mutants. The second mutant lacked four parental muropeptides which were composed of the unsubstituted disaccharide pentapeptide and its alanyl-tetraglycine derivative. The auxiliary genes are genetic determinants involved with the biosynthesis of peptidoglycan precursors, the presence of which in the cell wall may be needed for optimal cell wall turnover.

Increased expression of alpha IIb beta 3 integrin in subpopulations of murine melanoma cells with high lung-colonizing ability

Four subpopulations of B16 amelanotic melanoma cells, possessing different abilities to induce platelet aggregation (TCIPA) and to form lung colonies, were isolated by centrifugal elutriation. The expression of alpha IIb beta 3, alpha v beta 3 and alpha 5 beta 1 integrins was examined in the 4 subpopulations in order to determine the relationship between integrin receptor expression and tumor-cell metastatic potential. The mRNA of alpha IIb, alpha 5, beta 1 and beta 3 was detectable in the 4 subpopulations by Northern blotting. A gradual increase in mRNAs and cell-surface immunoreactivity of the alpha IIb beta 3 receptor, but not in their gene copies, was observed from the low to the high metastatic subpopulations. The ability of tumor cells to adhere to fibronectin and subendothelial matrix (SEM) increased in parallel. In the high metastatic cells, the alpha IIb beta 3 receptors, but not the alpha 5 beta 1 receptors, were localized to focal adhesion plaques. Incubation of the high metastatic cells with alpha IIb beta 3-specific antibodies reduced their matrix adhesion, TCIPA and lung-colonizing abilities. In contrast, in the low met- astatic cells, SEM adhesion and lung-colony formation were not affected by anti-alpha IIb beta 3 antibody treatment. Incubation of either the low or the high metastatic subpopulation with an alpha 5 beta 1-specific antibody had no effect in vitro and showed a slight inhibition of lung colonization in vivo. Our results suggest that several phenotypic characteristics of the enhanced metastatic potential of B16a subpopulations may be mediated by increased expression of alpha IIb beta 3 receptors and that expression of these receptors may be regulated at the transcriptional level.

Isolation and sequence analysis of carp gonadotropin beta-subunit gene

Using the cDNA encoding the beta subunit of carp gonadotropin (cGTH-beta) as a probe, 14 clones containing cGTH-beta gene have been isolated from a carp genomic library. Nucleotide sequence analysis indicated that the transcriptional unit of the cGTH-beta gene is 1.2 Kb. Similar to mammalian GTH-beta genes, cGTH-beta gene contains three exons and two introns. The locations of the exon/intron junctions also correspond to those of mammalian GTH-beta gene. Using the primer extension assay, the start site of transcription was determined to be 35 or 37 bp upstream from the translation initiation codon. The TATAA box is present in the 5' flanking region of the gene, 21 bp upstream from the start site of transcription. Three polyadenylation signals, AATAAA, are located in the 3' noncoding region, 111, 430, and 442 bp downstream from the stop codon of translation, respectively.

Thrombotic thrombocytopenic purpura-like syndrome associated with systemic lupus erythematosus--combined treatment with plasmapheresis and fresh frozen plasma infusion

We report on a patient with systemic lupus erythematosus, who, during the course of the illness, developed thrombotic thrombocytopenic purpura. In this case, the coexistence of these two conditions was confirmed by laboratory and pathologic findings. The infusion of fresh frozen plasma with plasmapheresis reversed the course of thrombotic thrombocytopenic purpura.

Organization and nucleotide sequence of carp gonadotropin α subunit genes

We have used PCR to amplify and align the sequence of two genes encoding cGTH alpha. Both genes comprise four exons and three introns. The organization of cGTH alpha genes is very similar to that of mammalian GTH alpha genes. However, the cGTH alpha genes only span a region of 1.2 kb which is much smaller than those mammalian GTH alpha genes.

Distribution of type A and type B EBV in patients with nasopharyngeal carcinoma

The subtypes of Epstein-Barr virus (EBV) according to EBNA 2 genes were investigated in 53 nasopharyngeal carcinoma (NPC) biopsies in Taiwan by polymerase chain reaction (PCR) and by Southern blot hybridization method. EBV DNA was found present in all NPC biopsies. Type A was the predominant type and comprised of 94.3% of the EBV of NPC. Type B or coinfection of type A and type B comprised of only 3.8% and 1.9% respectively.

Regioselective chloride ion loss from chlorine-37 enriched polychlorodibenzofurans by negative-ion mass spectrometry

Regiospecific chlorine-37 enriched dichloro-, trichloro-, tetrachloro-, and pentachlorodibenzofuran isomers were investigated under electron capture negative-ion mass spectrometry (ECNIMS) conditions. The relative chloride ion loss from the enriched positions was determined from the chloride-37 and chloride-35 ion abundances after correcting for the isotopic enrichment. Regioselective chloride anion losses were observed with the carbon 3-chlorine bond (beta-chlorine) generally found to be the most labile. The carbon-chlorine bond cleavages can be loosely associated with calculated carbon-chlorine bond residual charges.

Rapid detection of hog cholera virus in tissues by the polymerase chain reaction

A rapid method for the detection of hog cholera virus (HCV) in infected tissues, using polymerase chain reaction (PCR) was developed. Total RNA isolated from HCV-infected tissues was reverse transcribed with AMV reverse transcriptase and the resulting complementary DNA was amplified by Taq DNA polymerase in the presence of two HCV-specific primers. The amplified DNA fragment was detected by agarose gel electrophoresis. The sensitivity of this method was at 10(4) TCID50 of HCV. The sensitivity increased approximately 1000-fold when the DNA was reamplified with a set of nested primers. DNA sequencing analysis of the PCR products revealed that the HCV sequence amplified from a local field isolate was highly homologous to the HCV Alfort strain. This method may be useful for pathological and epidemiological studies of HCV in pigs.

Expression of perforin by natural killer cells within first trimester endometrium in humans

The lymphocyte pore-forming protein (PFP)--perforin, also named cytolysin--is a potent mediator of cytotoxicity found in the granules of cytotoxic T lymphocytes and natural killer (NK) cells. Granulated metrial gland (GMG) cells found in the pregnant mouse uterus express perforin and are thought to be highly activated cytolytic lymphocytes related to NK cells. Their role in pregnancy is unknown. Human endometrial granulocytes (EGs) are phenotypically similar to murine GMG cells and, like them, express NK cell markers. However, up to now it was not known whether EGs also express perforin. By means of immunohistochemical analysis, using antisera specific for perforin and monoclonal antibodies to CD56 (NKH-1), CD2 (T11), CD3 (Leu-4), CD4 (Leu-3a), and CD8 (OKT-8), we demonstrated that perforin is present in EGs in the decidualized endometrial stroma and decidual tissue of first-trimester gestational endometrium. In fact, double immunohistochemical labeling demonstrated the co-expression of perforin and NKH-1. This population also expressed some T-cell surface antigens (Leu-4 and T11), but not Leu-3a or OKT-8. Chorionic villi, in contrast, lack perforin+ cells. The presence of a potent cytolytic mediator in NK-like cells in both murine and human pregnant uterus raises the issue of the function of such cells in pregnancy.

Expression of two forms of carp gonadotropin alpha subunit in insect cells by recombinant baculovirus

There are two types of cDNA clones (designated alpha 1 and alpha 2) encoding the alpha subunit of carp gonadotropin. These two cDNAs are derived from different genes and encode proteins that differ by seven amino acid residues (three in the signal peptide and four in the mature polypeptide). Expression of these two cDNAs in insect cells by recombinant baculovirus revealed that the alpha 1 subunit, after noncovalent association with the beta subunit, has the same potency as the native alpha subunit purified from the pituitary. In contrast, the alpha 2 subunit can associate with the beta subunit, but only to form an inactive gonadotropin. Competition of the alpha 2 subunit with the alpha 1 subunit for association with the beta subunit decreases the gonadotropin activity of the alpha/beta complex. In addition, both alpha 1 and alpha 2 subunits are secreted into the culture medium by insect cells and have an apparent molecular mass approximately 5 kDa higher than that of the native alpha subunit. These results indicate that the insect cell-derived alpha 1 subunit is biologically active and that those four amino acid changes in the mature of alpha 2 protein affect the biological activity and thus provide valuable clues for the study of the structure-function relationship of the alpha subunit of glycoprotein hormones.

Human aortic proteoglycans of subjects from districts of high and low prevalence of atherosclerosis in China

The contents of three species of proteoglycans (PGs), heparan sulfate PG(HSPG), chondroitin sulfate PG(CSPG) and dermatan sulfate chondroitin sulfate PG(DSCSPG), in human thoracic aortas of subjects from districts of high (Beijin, in North China) and low (Nanning, in South China) prevalence of atherosclerosis in China were quantitated. Higher aortic HSPG and DSCSPG (but lower DS) in samples from Nanning than those from Beijing might be implicated in the lower prevalence of atherosclerosis in the former.

The efficacy of a combination administration of gonadotropin-releasing hormone agonist and gonadotropins for controlled ovarian hyperstimulation in IVF program

In 105 patients with the past history of poor response to the previous controlled ovarian hyperstimulation (COH) due to poor follicular growth or premature LH surge, the efficacy of pituitary suppression with gonadotropin-releasing hormone agonist (GnRHa) in IVF/GIFT program was evaluated in 112 cycles of COH using a combination regimen of leuprolide acetate (Lupron) and FSH/hMG or pure FSH from May to December, 1989. After suppression phase, serum E2 and progesterone levels decreased significantly, but there was no change in serum LH and FSH levels. There was no occurrence of premature LH surge during COH. Eleven cycles (9.8%) were cancelled, and 3 cycles (3.0%) failed in the transvaginal oocytes retrieval. The 7.00 +/- 3.32 follicles (FD greater than or equal to 12 mm) were observed, and 6.11 +/- 4.15 oocytes were retrieved. The 3.59 +/- 2.57 oocytes were fertilized and cleaved with the cleavage rate of 55.7%. In 83 IVF patients, 4.08 +/- 2.39 embryos were transferred, and 16 pregnancies were obtained with the pregnancy rate per ET of 19.3%. In 6 GIFT patients, 7.83 +/- 3.31 oocytes were available for transfer. When compared with the previous 108 cycles, the cancellation rate during COH was decreased and all the parameters of the outcome of COH including the pregnancy rate were increased. These data suggest that GnRHa therapy for pituitary suppression is an effective adjunct to the current gonadotropin regimens for COH in IVF/GIFT and can increase the probability of oocytes retrieval and pregnancy, especially in the previous poor responders.

Detection of Epstein-Barr virus DNA sequences in nasopharyngeal carcinoma cells by enzymatic DNA amplification

The presence of Epstein-Barr virus (EBV) DNA sequences was examined by the polymerase chain reaction in 50 nasopharyngeal carcinoma (NPC) biopsy specimens and in two primary epithelial tumor cell cultures derived from patients with NPC. The detection limit was a single EBV genome equivalent by agarose gel electrophoresis followed by Southern blot analysis of the amplified products. EBV DNA sequences were detected in all 41 undifferentiated NPC cell specimens, in 2 of 4 moderately differentiated NPC cell specimens, and in 3 of 5 keratinized NPC cell specimens. Undifferentiated NPC cells were also found to contain higher copy numbers of EBV than cells of the other two types of NPC. Our data suggest that EBV replication may be closely associated with the differentiation of NPC tumor cells. The results also demonstrated a sensitive and specific method for the detection of EBV DNA sequences in NPC tumor cells.

Cathepsin B to cysteine proteinase inhibitor balance in metastatic cell subpopulations isolated from murine tumors

Our laboratories have previously demonstrated that the malignancy of human and animal tumors is associated with increases in cathepsin B activity, due in part to increases in cathepsin B-specific RNA transcripts and in part to decreased regulation by the endogenous low molecular weight cysteine proteinase inhibitors (CPIs). In this study we have extended these observations to tumor cell subpopulations of B16 amelanotic melanoma (B16a) and Lewis lung carcinoma (3LL) isolated by centrifugal elutriation. B16a subpopulations exhibited a 10-fold differential in lung colonization potential, whereas 3LL subpopulations exhibited no differential. In the B16a subpopulations, cathepsin B activities, total cellular and plasma membrane-associated, corresponded positively (4- and 10-fold increase, respectively) with their lung colonization potentials. CPI activities, total cellular and plasma membrane-associated, corresponded inversely (2- and 5-fold decrease, respectively) with the lung colonization potential of the B16a subpopulations. In the 3LL subpopulations, neither cathepsin B nor CPI activities changed. In the plasma membrane fractions of all 3LL subpopulations the ratio of cathepsin B activity to CPI activity was less than 1, whereas in the plasma membrane fractions of all B16a subpopulations the ratio was 1 or greater. In the plasma membrane fractions of the B16a subpopulations of higher lung colonization potential the ratios were 2.5 and 7, indicating that the levels of endogenous CPIs in these fractions may not be sufficient to regulate cathepsin B activity. Cathepsin B mRNA levels were not increased in the B16a subpopulations expressing increased cathepsin B activity. Thus increased cathepsin B activity in these subpopulations was apparently due not to increased synthesis but to decreased regulation by the endogenous CPIs. These results suggest that membrane-associated cathepsin B and CPIs may both play a role in the expression of the experimental metastatic phenotype.

Oocyte donation program using a simplified hormonal regimen

It has been well recognized that both the synchronization of luteinizing hormone (LH) surge between the donor and the recipient for normally cycling women and the complex steroid replacement regimen given on a sequential and incremental basis for women with primary or secondary ovarian failure are two important aspects in oocyte donation. In oocyte donation program at SNUH, a simplified hormonal regimen applicable both to normally cycling women and to those with ovarian failure which consisted of administering 2 mg estradiol (E2) valerate orally 3 times a day augmented with 100 mg progesterone (P) in oil intramuscularly daily starting on the day preceding the oocyte retrieval from the donor was utilized. From July 1988 to December 1989 at SNUH, 11 cycles of oocyte donation program in 10 infertile patients were undertaken and 5 patients succeeded in pregnancy.

Purification, characterization, and molecular cloning of gonadotropin subunits of silver carp (Hypophthalmichthys molitrix)

The alpha and beta subunit of silver carp gonadotropin (scGTH-alpha and scGTH-beta) were isolated by high-performance liquid chromatography. Heterogeneity of N-terminal amino acid sequence was observed in scGTH-alpha but not in scGTH-beta. For determining the complete primary structures of scGTH-alpha and scGTH-beta, their cDNAs were cloned. Combining the data of N- and C-terminal sequences determined from proteins and the amino acid sequences deduced from cDNAs, we infer that scGTH-alpha consists of 95 and/or 93 residues and scGTH-beta consists of 115 residues. Both scGTH-alpha and scGTH-beta are glycoprotein. Their carbohydrate content is about 20 g per 100 g protein. The molecular weights of scGTH-alpha and scGTH-beta were calculated to be 12,700 and 15,700 Da, respectively. The amino acid sequences of scGTH-alpha and scGTH-beta are very similar to those of the corresponding subunit of carp GTH, different in only 2 and 4 residues, respectively. In addition, a high extent of homology (70%) was also observed between the alpha subunits of fish and mammalian GTHs. In the case of beta subunit, homology among various species of fish (75 to 98%) is much higher than that between fish and mammal (40%). These data suggest that the alpha subunit is conserved while the beta subunit is diversified during the molecular evolution of vertebrate GTH.