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Biomedical subjects

C T Wang

Publications and source records attributed to C T Wang.

At least 37 records · Page 2Linked to original sources
PubMed1999

Predominant inhibition of ganodermic acid S on the thromboxane A2-dependent pathway in human platelets response to collagen.

Ganodermic acid S (GAS), a membrane acting agent, exerts multiple effects on human platelet function (C.N. Wang et al. (1991) Biochem. J. 277, 189-197). The study reported how GAS affected the response of human gel-filtered platelets (GFP) to collagen. The agent inhibited cell aggregation by prolonging lag and shape change periods and decreasing the initial cell aggregation rate. However, the inhibitory efficiency was less than its inhibition on GFP response to U46619, a thromboxane (TX) A2 mimetic. In the agent-effect on biochemical events, GAS effectively inhibited Ca2+ mobilization, phosphorylation of myosin light chain, dense granule secretion and TXB2 generation. The inhibitions might originate from blocking Ca2+ mobilization of the TXA2-dependent pathway. GAS partially decreased the phosphorylation of most phosphotyrosine proteins from early activation to the integrin alphaIIbbeta3-regulated steps. The agent did not affect the phosphorylation of three proteins at the steps regulated by integrin alphaIIbbeta3. The results suggest that GAS inhibits the collagen response predominantly on the TXA2-dependent signaling, and the tyrosine kinase-dependent pathway in collagen response plays a major role in aggregation.

Blood Platelets↗
PubMed1999

Cation permeability and cation-anion interactions in a mutant GABA-gated chloride channel from Drosophila.

To investigate the structural basis of anion selectivity of Drosophila GABA-gated Cl(-) channels, the permeation properties of wild-type and mutant channels were studied in Xenopus oocytes. This work focused on asparagine 319, which by homology is one amino acid away from a putative extracellular ring of charge that regulates cation permeation in nicotinic receptors. Mutation of this residue to aspartate reduced channel conductance, and mutation to lysine or arginine increased channel conductance. These results are consistent with an electrostatic interaction between this site and permeating anions. The lysine mutant, but not the arginine mutant, formed a channel that is permeable to cations, and this cannot be explained in terms of electrostatics. The lysine mutant had a 25-mV reversal potential in solutions with symmetrical Cl(-) and asymmetrical cations. The permeability ratio of K(+) to Cl(-) was determined as 0. 33 from reversal potential measurements in KCl gradients. Experiments with large organic cations and anions showed that cation permeation can only be seen in the presence of Cl(-), but Cl(-) permeation can be seen in the absence of permeant cations. Measurements of permeability ratios of organic anions indicated that the lysine mutant has an increased pore size. The cation permeability of the lysine-containing mutant channel cannot be accounted for by a simple electrostatic interaction with permeating ions. It is likely that lysine substitution causes a structural change that extends beyond this one residue to influence the positions of other channel-forming residues. Thus protein conformation plays an important role in enabling ion channels to distinguish between anions and cations.

Amino Acid Sequence↗
PubMed1999

Heritabilities and genetic correlations of body weights and feather length in growing Muscovy selected in Taiwan.

1. Heritabilities and genetic correlations in the base population of a closed strain of Muscovy duck, moderately selected for body weight at 10 weeks of age, have been estimated from the data of 9 successive generations for the following traits: male and female body weight at 10 and 18 weeks of age (BW10m, BW18m, BW10f, BW18f) and length of the 8th primary feather at 10 weeks of age (F110m, F110f). 2. Multivariate REML with an animal model was used, pooling data from the 9 generations (3283 and 3289 male and female offspring respectively). The same trait expressed in male and female was considered as 2 different traits. 3. The 8th primary feather was longer in females than in males by 6% to 22% at 10 weeks of age. Body weight was heavier in males than in females by 42% to 58% at 10 weeks of age and by 57% to 75% at 18 weeks of age. 3. The heritability estimates for body weight traits showed moderate values, being a little higher for females than for males at the same age, increasing with age from h2=0.24 at BW10m to h2=0.43 at BW18f. 4. The heritability estimates for feather length showed that a greater response would be obtained in selection for male feather length (h2=0.37) than for female length (h2=0.14). Both have high genetic correlations with body weight so they could be indirectly improved. 5. Heritabilities of the difference in body weights between males and females at 10 weeks (h2=0.07) and 18 weeks of age (h2=0.10) were small, as well as for feather length (h2=0.10). It would probably be difficult to modify sexual dimorphism in body weight through selection. 6. Genetic correlations between BW10m, BW18m and BW10f, BW18f were respectively r(g)=0.77 and r(g)=0.80. They were larger for body weight at the same ages between males and females, r(g)=0.90 (r(g)=0.88 between F110m and F110f). Body weight in males and females at the same age should be better considered as 2 different traits in a selection programme. 7. The cumulated predicted genetic gains expressed per unity of the genetic standard deviation (sigma(g)) over the 8 generations of selection were 1.3 sigma(g) and 1.4 sigma(g) respectively for the BW10m and BW10f. The predicted correlated responses were 1.2 sigma(g) for body weights at 18 weeks of age, 0.9 sigma(g) and 0.7 sigma(g) for F110f and F110m respectively.

Animals↗
PubMed1999

Proximal tubular angiotensin II levels and renal functional responses to AT1 receptor blockade in nonclipped kidneys of Goldblatt hypertensive rats.

-Previous studies have shown that whereas the nonclipped kidney in two-kidney, one clip (2K1C) rats undergoes marked depletion of renin content and renin mRNA, intrarenal angiotensin II (Ang II) levels are not suppressed; however, the distribution and functional consequences of intrarenal Ang II remain unclear. The present study was performed to assess the plasma, kidney, and proximal tubular fluid levels of Ang II and the renal responses to intrarenal Ang II blockade in the nonclipped kidneys of rats clipped for 3 weeks. The Ang II concentrations in proximal tubular fluid averaged 9.19+/-1.06 pmol/mL, whereas plasma Ang II levels averaged 483+/-55 fmol/mL and kidney Ang II content averaged 650+/-66 fmol/g. Thus, as found in kidneys from normal rats with normal renin levels, proximal tubular fluid concentrations of Ang II are in the nanomolar range. To avoid the confounding effects of decreases in mean arterial pressure (MAP), we administered the nonsurmountable AT1 receptor antagonist candesartan directly into the renal artery of nonclipped kidneys (n=10). The dose of candesartan (0.5 microg) did not significantly decrease MAP in 2K1C rats (152+/-3 versus 148+/-3 mm Hg), but effectively prevented the renal vasoconstriction elicited by an intra-arterial bolus of Ang II (2 ng). Candesartan elicited significant increases in glomerular filtration rate (GFR) (0.65+/-0. 06 to 0.83+/-0.11 mL. min-1. g-1) and renal blood flow (6.3+/-0.7 to 7.3+/-0.9 mL. min-1. g-1), and proportionately greater increases in absolute sodium excretion (0.23+/-0.07 to 1.13+/-0.34 micromol. min-1. g-1) and fractional sodium excretion (0.38+/-0.1% to 1.22+/-0. 35%) in 2K1C hypertensive rats. These results show that proximal tubular fluid concentrations of Ang II are in the nanomolar range and are much higher than can be explained on the basis of plasma levels. Further, the data show that the intratubular levels of Ang II in the nonclipped kidneys of 2K1C rats remain at levels found in kidneys with normal renin content and could be exerting effects to suppress renal hemodynamic and glomerular function and to enhance tubular reabsorption rate.

Angiotensin I↗
PubMed1999

Intrarenal angiotensin II generation and renal effects of AT1 receptor blockade.

The intrarenal renin-angiotensin system plays a critical role in the paracrine regulation of renal function and the pathophysiology of hypertension. Angiotensin II (AngII) is formed intrarenally from systemically delivered angiotensin I (AngI) and intrarenally formed AngI. Intrarenal AngII content, which is greater than can be explained by the circulating AngII concentrations, is compartmentalized such that proximal tubule concentrations of AngI and AngII greatly exceed plasma concentrations. Proximal tubule cells are thought to secrete AngII or precursors of AngII into the tubular fluid to activate luminal AngII receptors. Recent immunohistochemical studies have demonstrated an abundance of AT1 receptors on the luminal surface of proximal and distal tubule cells and on afferent and efferent arteriolar vascular smooth muscle cells and mesangial cells of glomeruli. Activation of luminal AT1 receptors stimulates tubular sodium reabsorption rate. To evaluate the direct effects of AT1 receptor blockade on renal function in AngII-dependent hypertension, experiments were performed on two-kidney, one-clip (2K1C) Goldblatt hypertensive rats. Although the nonclipped kidney is renin-depleted, the intrarenal AngII levels are not suppressed, and AngII concentrations in proximal tubular fluid remain high (10(-8) M). Candesartan was administered into the renal artery of nonclipped kidneys to avoid the confounding consequences of decreases in arterial pressure. Blockade of intrarenal AT1 receptors elicited significant increases in GFR, renal blood flow, sodium excretion, and fractional sodium excretion, suggesting synergistic actions on tubular transport and vascular smooth muscle cells.

Angiotensin I↗
PubMed1999

The Ilizarov technique for treatment of sequelae of childhood-acquired bone and joint infection.

Bone and joint infections in childhood can result in various sequelae including deformity and limb length discrepancy (LLD). Management of these sequelae is difficult and must be individualized. In this study, we retrospectively examined the efficacy of treatment with Ilizarov techniques in 30 patients suffering from sequelae of bone and joint infections in childhood, treated from 1989 to 1994. These cases comprised 17 hip infections, two septic shoulders, and 11 cases of osteomyelitis (4 femurs, 5 tibiae, 1 humerus, and 1 forearm). All patients had some evidence of LLD. There were 13 cases of hip deformity and 10 cases of unstable hips. There were also 10 cases of angular deformity and five of nonunion of bone. The mean age at treatment was 21 years. Twenty-eight patients underwent Ilizarov lengthening procedures and 18 of them underwent deformity or instability correction simultaneously. Two patients underwent Ilizarov deformity correction only. Various techniques were used, including Schanz osteotomy plus mid-shaft femoral lengthening and distraction callotasis with and without an intramedullary nail. Postoperative complications included stiffness of joints in six patients, pin tract infection in six, fracture in five, malunion in five, nonunion in four, callus shortening in four, nerve palsy in two, and over-lengthening in one. The mean duration of follow-up was 72 months. The average length gain was 6.6 cm in shortened bones, with a mean external fixator index of 40.5 days/cm. All patients were satisfied with the functional and cosmetic results. We conclude that Ilizarov techniques are effective in treating sequelae of childhood infections of bones and joints.

Adult↗
PubMed1999

Sequence requirements for incorporation of human immunodeficiency virus gag-beta-galactosidase fusion proteins into virus-like particles.

The incorporation of human immunodeficiency virus type 1 (HIV-1) Gag-beta-galactosidase (Gag-beta-gal; GBG) fusion proteins into HIV virus-like particles in the presence of HIV Gag proteins was studied. HIV Gag-beta-gal fusion constructs were cotransfected individually into COS7 cells with or without an HIV Gag protein expression plasmid. Release of HIV GBG fusion proteins from the cells were measured by assay of the medium versus intracellular beta-gal activities. Analysis indicates that fusion proteins (constructs HIVGBG, GBG 1919 and 1877) retaining the C-terminal portion of the CA and the adjacent NC domains were efficiently assembled into virus-like particles. Fusion proteins with deleted sequences covering the N-terminal portions of the gag sequences (GBG 831, 1147, 1419, 1447, 1511, 1552, 1600, 1630, 1684, 1715, and 1752) were impaired in entry into virus-like particles. The presence of CA major homology region (MHR) in the fusion proteins had no significant effects on inducing fusion protein incorporation when the C-terminal CA sequences in the fusion proteins were truncated (GBG 1841 and 1801). Subcellular fractionation studies indicated that most fusion proteins including the nonmyristylated one were enriched in the crude membrane fraction. Exceptions to this rule were fusion proteins with intact MHR but truncated C-terminal CA sequences, which possessed low levels of membrane association. However, assembly of fusion proteins into HIV Gag particles did not correlate with their subcellular fractionation or immunofluorescence localization patterns. Overall, the studies suggest that the very C-terminal CA and adjacent NC sequences are the primary determinants for incorporation of HIV Gag-beta-gal fusion proteins into virus particles.

Animals↗
PubMed1999

Diagnosing and treating asymptomatic tuberculosis infection.

OBJECTIVE: To summarize relevant parts of the guidelines recommended by the Canadian and American Thoracic Societies for diagnosis and management of asymptomatic tuberculosis (TB) infection. QUALITY OF EVIDENCE: The latest guidelines published by the Canadian and American Thoracic Societies were reviewed. Unfortunately, neither of these guidelines state explicitly how recommendations were derived. The references accompanying each set of guidelines, however, suggest that they were developed by extensive literature review of the subject and consensus among expert panels. MAIN MESSAGE: Only higher-risk patients should receive a TB screening test (Mantoux test) to minimize the possibility of false-positive test results. The cutoff points for positive tests vary to reflect the pretest likelihood of TB infection. An induration 5 mm or greater is considered positive in patients at highest risk of TB infection, that is, HIV-infected patients, close contacts of active TB cases, and patients with chest x-ray abnormalities suggestive of previous untreated TB. All other patients are considered positive if they have induration greater than 10 mm according to the Canadian guideline. A 15-mm cutoff point, however, is used for patients without risk factors in the American guideline. All patients with positive Mantoux test results should be considered infected with TB. Infected patients should be offered 6 to 12 months of isoniazid prophylaxis if they have HIV infection, if they have medical conditions that increase the risk of TB activation, or if they are younger than 35 years. CONCLUSIONS: Prophylactic treatment of infected individuals effectively prevents the spread of TB infection. Family physicians, who most often see patients in the asymptomatic stage of TB infection, are uniquely situated to prevent secondary cases of TB by offering appropriate patients prophylactic treatment. Patients should be counseled about the risk and benefit of prophylactic treatment so they give informed consent for it.

Adult↗
PubMed1999

[Effect of the number of splinted abutments on stress distribution of support tissue]

OBJECTIVE:This study applied an SJ-1 bolt attachment partial denture to restorate distal extension edentulous areas.Finite element analysis (FEA) was used to monitor induced around abutment supporting tissues under the different number of splinted abutments.METHODS:Finite element analysis. RESULTS:The result demonstrate that the reduction of the number of splinted unit from three to two resulted in an insignificant increase of stress records,whereas reduction of the number from two to one resulted in a significant increase of stress nine times greater than the three unit splint values.CONCLUSION:Hence,at least two teeth on each side should be splinted when SJ 1 bolt(extracoronal) distal extension attachment prostheses are used.

Journal Article↗
PubMed1999

[Effect of the abutments with reduced periodontal support on stress distribution of support tissue]

OBJECTIVE:This study applied finite element analysis (FEA) compared stress distribution characteristics of mandible,bilateral,SJ-1 bolt(extracoronal) distal extension attachment prostheses when the abutments were subject to eight different loss of periodontal support.METHODS:Finite element analysis.RESULTS:It was shown that periodontal support loss results in increased stress of the terminal abutment tooth without sudden changes.CONCLUSION:Compared favorable stress distribution result from splinted compromised abutment,and the first premolar periodontal support loss less than that of the second premolar and this loss below 30%.

Journal Article↗
PubMed1999

A human cell line constitutively expressing HIV-1 Gag and Gag-Pol gene products.

A human cell line constitutively expressing the HIV-1 gag and pol genes products was established. The cell line was established by stably transfecting 293 cells with a plasmid construct that expresses the HIV Gag and Pol and can confer the transfectants resistant to mycophenolic acid. Particles generated from transient expression of the plasmid construct were noninfectious when pseudotyped with HIV envelope or with amphotropic murine leukemia virus envelope proteins. However, virus-like Gag particles produced by the stable cell line were appropriately processed, exhibited a wild-type retrovirus particle density, and possessed significant reverse-transcriptase (RT) activities. Continuous passage of the cell line either in the presence or absence of mycophenolic acid had no major effects on the Gag processing efficiency, particle assembly, or RT activity release. It was also demonstrated that the proteolytic processing of the virus-like particles released from the cell line was inhibited by an HIV protease inhibitor, saquinavir. The establishment of a stable cell line producing noninfectious but proteolytically processed HIV Gag particles offers a safe, convenient tool for biochemical and immunological analysis of virus-like particle assembly and is very useful for the development of anti-HIV protease drugs.

Blotting, Western↗
PubMed1999

Concentrations and actions of intraluminal angiotensin II.

Although the presence of angiotensin II (AngII) receptors on the luminal membranes of proximal tubule cells has been recognized for many years, recent immunohistochemical studies using polyclonal and monoclonal antibodies to the AngII type 1 (AT1) receptor have demonstrated an abundance of the AT1 receptor not only on the luminal surface of proximal tubule cells but also on the luminal surfaces of distal nephron segments. An important role for these receptors in the regulation of tubular transport mechanisms was indicated by the recent findings of remarkably high proximal intratubular concentrations of AngII (in the range of 10(-9) to 10(-8) M). The high intratubular concentrations of AngII, as well as angiotensin I and angiotensinogen, are much greater than can be explained on the basis of delivery via glomerular filtration. When coupled with the findings demonstrating the presence of angiotensinogen and angiotensinogen mRNA in proximal tubule cells, the data indicate that AngII or precursors of AngII are secreted directly into the proximal tubule lumen by the epithelial cells. Although the mechanisms responsible for the regulation of intratubular AngII concentrations remain to be determined, micropuncture studies have provided direct evidence that activation of intraluminal AT1 receptors by AngII exerts a substantial stimulatory influence on sodium and bicarbonate transport by both proximal and distal tubules. Collectively, these data provide support for the hypothesis that activation of luminal AT1 receptors by AngII present in the tubular fluid contributes importantly to regulation of the tubular reabsorption rate.

Angiotensin II↗
PubMed1998

Analysis of minimal human immunodeficiency virus type 1 gag coding sequences capable of virus-like particle assembly and release.

We have constructed a series of human immunodeficiency virus (HIV) gag mutants by progressive truncation of the gag coding sequence from the C terminus and have combined these mutants with an assembly-competent matrix domain deletion mutation (DeltaMA). By using several methods, the particle-producing capabilities of each mutant were examined. Our analysis indicated that truncated Gag precursors lacking most of C-terminal gag gene products assembled and were released from 293T cells. Additionally, a mutant with a combined deletion of the MA (DeltaMA) and p6 domains even produced particles at levels comparable to that of the wild-type (wt) virus. However, most mutants derived from combination of the DeltaMA and the C-terminal truncation mutations did not release particles as well as the wt. Our smallest HIV gag gene product capable of virus-like particle formation was a 28-kDa protein which consists of a few MA amino acids and the CA-p2 domain. Sucrose density gradient fractionation analysis indicated that most mutants exhibited a wt retrovirus particle density. Exceptions to this rule were mutants with an intact MA domain but deleted downstream of the p2 domains. These C-terminal truncation mutants possessed particle densities of 1.13 to 1.15 g/ml, lower than that of the wt. The N-terminal portions of the CA domain, which have been shown to be dispensable for core assembly, became critical when most of the MA domain was deleted, suggesting a requirement for an intact CA domain to assemble and release particles.

Amino Acid Sequence↗
PubMed1998

Renoprotective effects of nitric oxide in angiotensin II-induced hypertension in the rat.

Experiments were performed in anesthetized male Sprague-Dawley rats to determine whether increased nitric oxide (NO) activity during the development of hypertension exerts a protective effect on renal cortical blood flow (CBF) and medullary blood flow (MBF). The effects of acute NO synthase inhibition on renal function and on CBF and MBF, measured by laser-Doppler flow probes, were evaluated in control and ANG II-infused hypertensive rats, prepared by the infusion of ANG II at a rate of 65 ng/min via osmotic minipumps implanted subcutaneously for 13 days. In normotensive rats (n = 8), intravenous infusion of N omega-nitro-L-arginine (NLA; 20 micrograms.100 g-1.min-1) decreased CBF by 21 +/- 4% and MBF by 49 +/- 8% and increased blood pressure from 118 +/- 1 to 140 +/- 2 mmHg. In ANG II-infused rats (n = 7), CBF and MBF decreased by 46 +/- 5% and 25 +/- 6%, respectively, during infusion of NLA. Arterial pressure increased from 160 +/- 5 to 197 +/- 7 mmHg, which was a greater absolute increase than in normotensive controls. Basal renal blood flow (RBF), estimated from p-aminohippurate clearance and hematocrit, was similar in both the control (6.0 +/- 0.5 ml.min-1.g-1) and hypertensive (6.0 +/- 0.6 ml.min-1.g-1) rats. However, NLA-induced reductions in RBF averaged 60 +/- 5% in the hypertensive rats, compared with 31 +/- 9% observed in control rats. GFR in control (0.97 +/- 0.03 ml.min-1.g-1) and hypertensive rats (0.78 +/- 0.12 ml.min-1.g-1) decreased to a similar extent during the first 30-min period of NLA infusion. GFR returned toward control levels in control rats; in contrast, GFR remained significantly decreased in the ANG II-infused rats (0.58 +/- 0.11 ml.min-1.g-1). Basal urinary sodium excretion (0.2 +/- 0.08 mueq.min-1.g-1), fractional excretion of sodium (0.3 +/- 0.13%), and urine flow (4.9 +/- 0.39 microliters.min-1.g-1) in hypertensive rats did not increase significantly after NLA treatment as occurred in normotensive controls. These data suggest that a compensatory increase in nitric oxide activity partially counteracts the vasoconstrictor influence of elevated ANG II levels to regulate renal hemodynamics and maintain cortical perfusion in the renal circulation.

Angiotensin II↗
PubMed1998

Effects of acute AT1 receptor blockade by candesartan on arterial pressure and renal function in rats.

Experiments were performed on normal anesthetized rats to determine the effects of candesartan, a novel AT1 receptor antagonist, on the arterial pressure and renal hemodynamic responses to bolus doses of angiotensin II (ANG II) and on renal hemodynamics and sodium excretion. Control arterial pressure responses to bolus ANG II doses of 10, 50, 100 and 1,000 ng were 26 +/- 6, 54 +/- 7, 57 +/- 7, and 79 +/- 7 mmHg; the decreases in cortical renal blood flow (CRBF), measured with laser-Doppler flowmetry, were 47 +/- 9, 64 +/- 8, 71 +/- 6, and 82 +/- 6%. The vasoconstrictor responses to ANG II up to 1,000 ng were completely blocked by candesartan doses of 1 and 0.1 mg/kg, whereas treatment with 0.01 mg/kg candesartan attenuated the arterial pressure and CRBF responses. The higher doses of candesartan (1 and 0.1 mg/kg) elicited rapid decreases in arterial pressure, leading to associated decreases in sodium excretion. Renal blood flow (RBF), glomerular filtration rate (GFR), and urine flow also decreased following treatment with candesartan at 1 mg/kg. In contrast, when candesartan was given at 0.01 mg/kg, which did not decrease arterial pressure significantly, there were significant increases in GFR (16 +/- 4), RBF (9 +/- 2), urine flow (11 +/- 2), sodium excretion (35 +/- 7), and fractional sodium excretion (39 +/- 8%). The inability to overcome blockade, even with very high ANG II doses, indicates that candesartan is a potent noncompetitive blocker of ANG II pressor and renal vasoconstrictor effects. The lower candesartan dose that did not cause significant hypotension elicited substantial increases in RBF, GFR, and sodium excretion, revealing the direct renal vasodilator and natriuretic effects of AT1 receptor blockade.

Angiotensin II↗
PubMed1998

Survey of Theileria parasite infection in cattle in Taiwan.

An survey of Theileria parasite infection in cattle in Taiwan was carried out by polymerase chain reaction (PCR). A total of 491 blood samples, 105 from southern area and 386 from northern area, were collected from bovine in 16 different farms. From northern area, Theileria piroplasms could be seen in only 4 of 105 blood samples microscopically. However, when p32/34 genes (encoding immunodominant piroplasm surface proteins) were amplified by PCR, 15 blood samples were detected positive. They were analyzed by using allele-specific primers of 3 allelic forms of p32/34 and all contained C type of T. sergenti. Four blood samples were found infected with both C and B (T. buffeli) type parasites. Examination of 386 blood samples from southern area of Taiwan did not reveal any Theileria parasite microscopically, as well as by PCR amplification.

Animals↗
PubMed1997

Two tandemly repeated telomere-associated sequences in Nicotiana plumbaginifolia.

Two tandemly repeated telomere-associated sequences, NP3R and NP4R, have been isolated from Nicotiana plumbaginifolia. The length of a repeating unit for NP3R and NP4R is 165 and 180 nucleotides respectively. The abundance of NP3R, NP4R and telomeric repeats is, respectively, 8.4 x 10(4), 6 x 10(3) and 1.5 x 10(6) copies per haploid genome of N. plumbaginifolia. Fluorescence in situ hybridization revealed that NP3R is located at the ends and/or in interstitial regions of all 10 chromosomes and NP4R on the terminal regions of three chromosomes in the haploid genome of N. plumbaginifolia. Sequence homology search revealed that not only are NP3R and NP4R homologous to HRS60 and GRS, respectively, two tandem repeats isolated from N. tabacum, but that NP3R and NP4R are also related to each other, suggesting that they originated from a common ancestral sequence. The role of these repeated sequences in chromosome healing is discussed based on the observation that two to three copies of a telomere-similar sequence were present in each repeating unit of NP3R and NP4R.

Base Sequence↗