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Biomedical subjects

Jun Zhang

Publications and source records attributed to Jun Zhang.

At least 271 records · Page 15Linked to original sources
PubMed2004

Bmx, a member of the Tec family of nonreceptor tyrosine kinases, is a novel participant in pharmacological cardioprotection.

Previous studies have indicated that PKC-epsilon is a central regulator of protective signal transduction in the heart. However, the signaling modules through which PKC-epsilon exerts its protective effects have only begun to be understood. We have identified a novel participant in the PKC-epsilon signaling system in cardioprotection, the nonreceptor tyrosine kinase Bmx. Functional proteomic analyses of PKC-epsilon signaling complexes identified Bmx as a member of these complexes. Subsequent studies in rabbits have indicated that Bmx is activated by nitric oxide (NO) in the heart, concomitant with the late phase of NO donor-induced protection, and provide the first analysis of Bmx expression/distribution in the setting of cardioprotection. In addition, increased expression of Bmx induced by NO donors was blocked by the same mechanism that blocked cardioprotection: inhibition of PKC with chelerythrine. These findings indicate that a novel type of PKC-tyrosine kinase module (involving Bmx) is formed in the heart and may be involved in pharmacological cardioprotection by NO donors.

Alkaloids↗
PubMed2004

Selection of a peptide mimicking neutralization epitope of hepatitis E virus with phage peptide display technology.

AIM: To select the peptide mimicking the neutralization epitope of hepatitis E virus which bound to non-type-specific and conformational monoclonal antibodies (mAbs) 8C11 and 8H3 fromed 7-peptide phage display library, and expressed the peptide recombinant with HBcAg in E.coli, and to observe whether the recombinant HBcAg could still form virus like particle (VLP) and to test the activation of the recombinant polyprotein and chemo-synthesized peptide that was selected by mAb 8H3. METHODS: 8C11 and 8H3 were used to screen for binding peptides through a 7-peptide phage display library. After 4 rounds of panning, monoclonal phages were selected and sequenced. The obtained dominant peptide coding sequences was then synthesized and inserted into amino acid 78 to 83 of hepatitis B core antigen (HBcAg), and then expressed in E.coli. Activity of the recombinant proteins was detected by Western blotting, VLPs of the recombinant polyproteins were tested by transmission electron microscopy and binding activity of the chemo-synthesized peptide was confirmed by BIAcore biosensor. RESULTS: Twenty-one positive monoclonal phages (10 for 8C11, and 11 for 8H3) were selected and the inserted fragments were sequenced. The DNA sequence coding for the obtained dominant peptides 8C11 (N'-His-Pro-Thr-Leu-Leu-Arg-Ile-C', named 8C11A) and 8H3 (N'-Ser-Ile-Leu-Pro- Tyr-Pro-Tyr-C', named 8H3A) were then synthesized and cloned to the HBcAg vector, then expressed in E.coli. The recombinant proteins aggregated into homodimer or polymer on SDS-PAGE, and could bind to mAb 8C11 and 8H3 in Western blotting. At the same time, the recombinant polyprotein could form virus like particles (VLPs), which could be visualized on electron micrograph. The dominant peptide 8H3A selected by mAb 8H3 was further chemo-synthesized, and its binding to mAb 8H3 could be detected by BIAcore biosensor. CONCLUSION: These results implicate that conformational neutralizing epitope can be partially modeled by a short peptide, which provides a feasible route for subunit vaccine development.

Amino Acid Sequence↗
PubMed2004

A rapid and efficient method to express target genes in mammalian cells by baculovirus.

AIM: To investigate the modification of baculovirus vector and the feasibility of delivering exogenous genes into mammalian cells with the culture supernatant of Spodoptera frugiperta (Sf9) cells infected by recombinant baculoviruses. METHODS: Two recombinant baculoviruses (BacV-CMV-EGFPA, BacV-CMV-EGFPB) containing CMV-EGFP expression cassette were constructed. HepG2 cells were directly incubated with the culture supernatant of Sf9 cells infected by recombinant baculoviruses, and reporter gene transfer and expression efficiencies were analyzed by flow cytometry (FCM). The optimal transduction conditions were investigated by FCM assay in HepG2 cells. Gene-transfer and expression efficiencies in HepG2 or CV1 cells by baculovirus vectors were compared with lipofectAMINE, recombinant retrovirus and vaccinia virus expression systems. Twenty different mammalian cell lines were used to investigate the feasibility of delivering exogenous genes into different mammalian cells with the culture supernatant of infected Sf9 cells. RESULTS: CMV promoter could directly express reporter genes in Sf9 cells with a relatively low efficiency. Target cells incubated with the 1:1 diluted culture supernatant (moi=50) for 12 h at 37 degrees C could achieve the highest transduction and expression efficiencies with least impairment to cell viability. Under similar conditions the baculovirus vector could achieve the highest gene-transfer and expression efficiency than lipofectAMINE, recombinant retrovirus and vaccinia virus expression systems. Most mammalian cell lines could be transduced with recombinant baculovirus. In primate adherent culture cells the recombinant baculovirus could arrive the highest infection and expression efficiencies, but it was not very satisfactory in the cell lines from mice and suspended culture cells. CONCLUSION: Mammalian cells incubated with the culture supernatant of infected Sf9 cells could serve as a very convenient way for rapid and efficient expression of foreign genes in mammalian cells, but it might be more suitable for primate adherent culture cells.

Animals↗
PubMed2004

Multiple signal transducers and activators of transcription are induced by EBV LMP-1.

Epstein-Barr virus (EBV) latent membrane protein 1 (LMP-1) is required for EBV immortalization of primary B cells in vitro. Signal transducers and activators of transcription (STATs) play a pivotal role in the initiation and maintenance of certain cancers. STAT proteins, especially STAT-1, -3, and -5, are persistently tyrosine phosphorylated or activated in many cancers. We show here that EBV-infected type III latency cells, in which the EBV oncoprotein, LMP-1 is expressed, express high levels of four STATs (STAT-1, -2, -3, and -5A) and that LMP-1 is responsible for the induction of three (STAT-1, -2, and -3). In addition, the C-terminal activator region 1 (CTAR-1) and CTAR-2 of LMP-1 cooperatively induced the expression of STAT-1. The cooperativity was evident when CTAR-1 and CTAR-2 were present in cis, but not in trans. Furthermore, NF-kappaB is an essential factor involved in the induction of STAT-1. Most of the induced STATs were not phosphorylated at the critical tyrosine residue activated by many cytokines. However, the induced STATs, at least STAT-1, were functional because it could be activated by interferon (IFN) and could upregulate an IFN-inducible gene. Finally, expression of STAT-1, but not STAT-2 and -3, is associated with EBV transformation. The association of the expression of STAT-1, -2, -3, and -5A with EBV type III latency and the expression of STAT-1 in the EBV transformation process may be part of the viral programming that regulates viral latency and cellular transformation.

B-Lymphocytes↗
PubMed2004

Emission direction of fast electrons in laser-solid interactions at intensities from the nonrelativistic to the relativistic.

The emission direction of outward-ejecting fast electrons generated in laser-solid interactions by 30 fs laser pulses is measured for laser intensities varying from the nonrelativistic to the relativistic. For an s-polarized incident laser beam at nonrelativistic intensities, the ejected electrons are close to the polarization direction of the laser beam. With the increase of the laser intensity, the ejected electrons are still mainly within the polarization plane, but turn away from the laser polarization direction towards the opposite direction of the incident laser beam. At relativistic intensities, electrons eject towards the direction of the reflected laser beam. The increasing ponderomotive force acceleration with the laser intensities might be responsible for the observed changes.

Journal Article↗
PubMed2004

Barrett's esophagus and its correlation with gastroesophageal reflux in Chinese.

AIM: To study the prevalence of Barrett's esophagus in Chinese and its correlation with gastroesophageal reflux. METHODS: This study was carried out in a large prospective series of 391 patients who had undergone upper endoscopy. The patients were divided into 3 groups according to the position of squamocolumnar junction (SCJ). Reflux esophagitis (RE) and its degree were recorded. Intestinal metaplasia (IM) in biopsy specimen was typed according to histochemistry and HE and alcian blue (pH2.5) staining separately. Results correlating with clinical, endoscopic, and pathological data were analysed. RESULTS: The prevalence of IM endoscopically appearing Long-segment Barrett's Esophagus (LSBE) was 26.53%, Short-segment Barrett's Esophagus (SSBE) was 33.85% and gastroesophageal junction (GEJ) was 34.00%. IM increased with age of above 40 years old and no difference was found between male and female. Twelve were diagnosed as dysplasia (7 low-grade, 5 high-grade), 16 were diagnosed as cardiac adenocarcinoma and 1 as esophageal adenocarcinoma. The more far away the SCJ moved upward above GEJ, the higher the prevalence and the more severe the RE were. CONCLUSION: There was no difference of the prevalence of IM in different places of SCJ, and IM increased with age of above 40 years old. It is important to pay attention to dysplasia in the distal esophagus and gastro-esophageal junction, and adenocarcinoma is more common in cardia than in esophagus. BE is a consequence of gastroesophageal reflux disease.

Asian People↗
PubMed2004

Markers for detergent-resistant lipid rafts occupy distinct and dynamic domains in native membranes.

Lipid rafts isolated by detergent extraction and sucrose gradient fractionation from mast cells are enriched for the glycosylphosphatidylinositol-linked protein Thy-1, the ganglioside GM1, palmitoylated LAT, and cross-linked IgE receptors, FcepsilonRI. This study addresses the relationship of fractionation data to the organization of raft markers in native membranes. Immunogold labeling and electron microscopy shows there is little or no colocalization of the raft markers Thy-1, GM1, and LAT with each other or with FcepsilonRI on native membrane sheets prepared from unstimulated cells. External cross-linking of Thy-1 promotes coclustering of Thy-1 with LAT, but not with GM1. Thy-1 and LAT clusters occur on membrane regions without distinctive features. In contrast, external cross-linking of FcepsilonRI and GM1 causes their redistribution to electron-dense membrane patches independently of each other and of Thy-1. The distinctive patches that accumulate cross-linked FcepsilonRI and GM1 also accumulate osmium, a stain for unsaturated lipids, and are sites for coated vesicle budding. Electron microscopy reveals a more complex and dynamic topographical organization of membrane microdomains than is predicted by biochemical analysis of detergent-resistant membranes.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Cystatin M suppresses the malignant phenotype of human MDA-MB-435S cells.

Proteases are involved in many aspects of tumor progression, including cell survival and proliferation, escape from immune surveillance, cell adhesion and migration, remodeling and invasion of the extracellular matrix. Several lysosomal cysteine proteases have been cloned and shown to be overexpressed in cancer; yet, despite the great potential for development of novel therapeutics, we still know little about the regulation of their proteolytic activity. Cystatins such as cystatin M are potent endogenous protein inhibitors of lysosomal cysteine proteases. Cystatin M is expressed in normal and premalignant human epithelial cells, but not in many cancer cell lines. Here, we examined the effects of cystatin M expression on malignant properties of human breast carcinoma MDA-MB-435S cells. Cystatin M was found to significantly reduce in vitro: cell proliferation, migration, Matrigel invasion, and adhesion to endothelial cells. Reduction of cell proliferation and adhesion to an endothelial cell monolayer were both independent of the inhibition of lysosomal cysteine proteases. In contrast, cell migration and matrix invasion seemed to rely on lysosomal cysteine proteases, as both recombinant cystatin M and E64 were able to block these processes. This study provides the first evidence that cystatin M may play important roles in safeguarding against human breast cancer.

Breast Neoplasms↗
PubMed2004

[Effects of intravenous and inhalational anesthetics on short-latency somatosensory evoked potentials].

OBJECTIVE: To choose suitable general anesthetics dosages when short-latency somatosensory evoked potentials (SLSEP) is monitored during operation. METHODS: 150 ASA I-II neurosurgical patients undergoing elective operations were randomly divided into intravenous anesthesia group of 90 patients and inhalation anesthesia group of 60 patients. The intravenous anesthesia group was further divided into 9 subgroups of 10 patients treated with different anesthetics of different dosages: propofol (1.5 mg/kg, 2 mg/kg, and 3 mg/kg), midazolam (0.2 mg/kg, 0.3 mg/kg, and 0.4 mg/kg), and etomidate (0.15 mg/kg, 0.3 mg/kg, and 0.4 mg/kg). The intravenous anesthetics were given and upper limb SLSEP was monitored continuously. The inhalation anesthesia group was further divided into enflurane, isoflurane and desflurane subgroups of 20 patients each. The inhalational anesthetics were given at the concentrations corresponding to the end-expiratory concentrations of 0 to 0.3, 0.5, 0.75, 1.0 and 1.5 MAC. The changes of N(14), N(20) and central conduction time (CCT) were recorded. In addition to SLSEP, EKG, NIBP, SpO(2), P(ET) CO(2) were monitored as well as end-tidal anesthetic concentration. During the experiment SpO(2) was maintained > 95% and P(ET) CO(2) was maintained at the range of 35 - 45 mmHg by mask oxygen or assisted ventilation. RESULTS: The intravenous anesthetic propofol significantly decreased N(20) amplitude and produced less effect on the latency of N(14), N(20) and CCT. Midazolam significantly decreased the N(20) amplitude and prolonged the latency of N(20) and CCT. Etomidate significantly increased the N(20) amplitude, and the change did not recover when the patients had opened their eyes 10 minutes after medication. All three inhalational anesthetics significantly decreased the N(20) amplitude and prolonged the N(20) latency and CCT. N(20) amplitude disappeared in some patients treated with enflurane when the end-expiratory concentration was 1.0 MAC, while disappeared in some patients treated with isoflurane and desflurane when the end-expiratory concentration was 1.5 MAC for these 2 drugs. CONCLUSION: When using SLSEP monitoring, the most suitable general anesthetic is etomidate during the induction stage and isoflurane and desflurane during the maintenance stage with the end-expiratory concentration below 1.0 MAC.

Adolescent↗
PubMed2004

Relationship of gastric Helicobacter pylori infection to Barrett's esophagus and gastro-esophageal reflux disease in Chinese.

AIM: To evaluate the relationship of Helicobacter pylori infection to reflux esophagitis (RE), Barrett's esophagus (BE) and gastric intestinal metaplasia (IM). METHODS: RE, BE and gastric IM were determined by upper endoscopy. Patients were divided into 2 groups; those with squamocolumnar junction (SCJ) beyond gastroesophageal junction (GEJ) > =3 cm (group A), and those with SCJ beyond GEJ <3 cm (group B). Biopsy specimens were obtained endoscopically from just below the SCJ, gastric antrum along the greater and lesser curvature. Pathological changes and H pylori infection were determined by HE staining, Alcian blue staining and Giemsa staining. RESULTS: The prevalence of H pylori infection was 46.93%. There was no difference in the prevalence between males and females. The prevalence of H pylori infection decreased stepwise significantly from RE grade I to III. There was no difference in the prevalence between the two groups, and between long-segment and short-segment BE. In distal stomach, prevalence of H pylori infection was significantly higher in patients with IM than those without IM. CONCLUSION: There is a protective role of H pylori infection to GERD. There may be no relationship between H pylori infection of stomach and BE. H pylori infection is associated with the development of IM in the distal stomach.

Barrett Esophagus↗
PubMed2004

Identification of a ZU5 and death domain-containing inhibitor of NF-kappaB.

The transcription factor NF-kappaB plays important roles in inflammation and cell survival. NF-kappaB is composed of homodimeric and heterodimeric complexes of Rel/NF-kappaB family members, including p65 (RelA), c-Rel (Rel), RelB, NF-kappaB1/p50, and NF-kappaB2/p52. Here we report the identification and characterization of a novel ZU5 and death domain-containing protein designated ZUD. In reporter gene assays, overexpression of ZUD inhibited NF-kappaB-dependent transcription induced by both tumor necrosis factor (TNF) and interleukin-1 and their downstream signaling proteins. Gel shift assays indicated that the overexpression of ZUD inhibited binding of NF-kappaB to its target sequence. ZUD is a cytoplasmic protein, and coimmunoprecipitation assays indicated that ZUD interacted with the NF-kappaB subunit p105 and transactivator p65. Consistent with its role in inhibition of NF-kappaB-dependent transcription, ZUD sensitized cells to apoptosis induced by TNF and the TNF-related apoptosis-inducing ligand (TRAIL). Our findings suggest that ZUD is an inhibitor of NF-kappaB activation and that this protein may provide an alternative regulatory mechanism for NF-kappaB-mediated transcription.

Apoptosis↗
PubMed2004

Mechanisms of the TRIF-induced interferon-stimulated response element and NF-kappaB activation and apoptosis pathways.

Toll-like receptor-3 is critically involved in host defense against viruses through induction of type I interferons (IFNs). Recent studies suggest that a Toll/interleukin-1 receptor domain-containing adapter protein (TRIF) and two protein kinases (TANK-binding kinase-1 (TBK1) and IkappaB kinase (IKK)-epsilon) are critically involved in Toll-like receptor-3-mediated IFN-beta production through activation of IFN regulatory factor (IRF)-3 and IRF-7. In this study, we demonstrate that TRIF interacts with both IRF-7 and IRF-3. In addition to TBK1 and IKKepsilon, our results indicate that IKKbeta can also phosphorylate IRF-3 and activate the IFN-stimulated response element. TRIF-induced IRF-3 and IRF-7 activation was mediated by TBK1 and its downstream kinases IKKbeta and IKKepsilon. TRIF induced NF-kappaB activation through an IKKbeta- and tumor necrosis factor receptor-associated factor-6-dependent (but not TBK1- and IKKepsilon-dependent) pathway. In addition, TRIF also induced apoptosis through a RIP/FADD/caspase-8-dependent and mitochondrion-independent pathway. Furthermore, our results suggest that the TRIF-induced IFN-stimulated response element and NF-kappaB activation and apoptosis pathways are uncoupled and provide a molecular explanation for the divergent effects induced by the adapter protein TRIF.

Adaptor Proteins, Vesicular Transport↗
PubMed2004

Long-term outcome of esophageal myotomy for achalasia.

AIM: Modified Heller's myotomy is still the first choice for achalasia and the assessment of surgical outcomes is usually made based on the subjective sensation of patients. This study was to objectively assess the long-term outcomes of esophageal myotomy for achalasia using esophageal manometry, 24-hour pH monitoring, esophageal scintigraphy and fiberoptic esophagoscopy. METHODS: From February 1979 to October 2000, 176 patients with achalasia underwent modified Heller's myotomy, including esophageal myotomy alone in 146 patients, myotomy in combination with Gallone or Dor antireflux procedure in 22 and 8 patients, respectively. Clinical score, pressure of the lower esophageal sphincter (LES), esophageal clearance rate and gastroesophageal reflux were determined before and 1 to 22 years after surgery. RESULTS: After a median follow-up of 14 years, 84.5% of patients had a good or excellent relief of symptoms, and clinical scores as well as resting pressures of the esophageal body and LES were reduced compared with preoperative values (P<0.001). However, there was no significant difference in DeMeester score between pre- and postoperative patients (P=0.51). Esophageal transit was improved in postoperative patients, but still slower than that in normal controls. The incidence of gastroesophageal reflux in patients who underwent esophageal myotomy alone was 63.6% compared to 27.3% in those who underwent myotomy and antireflux procedure (P=0.087). Three (1.7%) patients were complicated with esophageal cancer after surgery. CONCLUSION: Esophageal myotomy for achalasia can reduce the resting pressures of the esophageal body and LES and improve esophageal transit and dysphagia. Myotomy in combination with antireflux procedure can prevent gastroesophageal reflux to a certain extent, but further randomized studies should be carried out to demonstrate its efficacy.

Adolescent↗
PubMed2004

Efficacy of Venlafaxine ER in patients with social anxiety disorder: a double-blind, placebo-controlled, parallel-group comparison with paroxetine.

This study evaluated the anxiolytic efficacy, safety and tolerability of a flexible dose of venlafaxine extended release (ER) compared with placebo and paroxetine in the short-term treatment of generalized social anxiety disorder (SAD). Adult outpatients with generalized SAD (n = 434) were randomized to receive capsules of venlafaxine ER 75 mg to 225 mg/day, paroxetine 20 mg to 50 mg/day, or placebo for 12 weeks. The primary efficacy variable was the Liebowitz social anxiety scale total score. Secondary efficacy variables included the patient-rated social phobia inventory and the proportion of responders in each group (a responder was defined as having a clinical global impression-improvement score of 1 or 2). Treatment with venlafaxine ER was associated with significantly greater improvement than treatment with placebo for all primary and secondary efficacy variables (p < 0.05). No significant differences in primary or secondary efficacy variables were observed between the venlafaxine ER and paroxetine groups. The week 12 response rates were 69%, 66% and 36% for the venlafaxine ER, paroxetine and placebo groups, respectively. Both active treatments were generally well tolerated and were associated with a similar incidence of adverse events. This study shows that venlafaxine ER is an effective, safe and well-tolerated drug treatment for SAD.

Adult↗
PubMed2004

Feasibility study of normal and septic tracheal imaging using optical coherence tomography.

BACKGROUND AND OBJECTIVES: Optical coherence tomography (OCT) is an imaging technology that may be adapted for use with flexible fiberoptic bronchoscopy, potentially allowing it to play an important role in pulmonary diagnostics. The goal of this study was to evaluate the feasibility of OCT to image tracheal pathology. STUDY DESIGN/MATERIALS AND METHODS: Tracheas were harvested from normal and septic New Zealand White rabbits and imaged using OCT. Two delivery devices were employed. One was a moving stage with an objective lens and collimator, the other a linear scanning flexible fiberoptic catheter using a GRIN lens and prism for endoscopic OCT. After OCT images were obtained from normal and septic tracheas, the excised tissues were prepared for standard histologic examination. Areas imaged by OCT were compared with corresponding histology slides. RESULTS: OCT images demonstrated in detail tracheal sub-surface structures such as the epithelium, lamina propria, submucosa, and cartilage. The appearance of structures imaged by OCT corresponded very well with histologic pictures obtained by light microscopy. The OCT images from septic tracheas showed marked swelling of the mucosal and submucosal layers. Such pathology was equally imaged by either the moving stage or fiberoptic catheter for endoscopic OCT. CONCLUSIONS: OCT images of the trachea can distinguish many sub-surface structural features usually requiring biopsy and light microscopy for visualization. Marked differences between normal and septic trachea were apparent in OCT images. In the future, OCT may be a valuable tool for evaluating tracheal pathology in situ with high image resolution.

Animals↗
PubMed2004

Method development for the quantitation of ABT-578 in rabbit artery tissue by 96-well liquid-liquid extraction and liquid chromatography/tandem mass spectrometric detection.

Quantitative determination of drug concentrations in tissue samples can provide critical information for drug metabolism, kinetics, and toxicity evaluations. For analysis of tissue samples using liquid chromatography/tandem mass spectrometric (LC/MS/MS) detection, homogenization is a critical step in achieving good assay performance. Assay performance can be closely evaluated by spiking the drug directly into tissue samples prior to homogenization. It is especially important to include this assay evaluation for the analysis of artery tissue samples because artery tissue is very elastic, making it quite a challenge to develop an effective procedure for homogenization. An LC/MS/MS assay in 96-well format using liquid-liquid extraction was developed for analyzing ABT-578 in rabbit artery samples. Tissue quality control samples were prepared by spiking ABT-578 stock solutions directly into the tissue before homogenization. The usage of the tissue control samples gives a thorough evaluation of the sample preparation process that includes both homogenization and sample extraction. A 20% blood in saline solution was used as a homogenization solution. Calibration standards were made by spiking ABT-578 into rabbit whole blood. Blood quality control samples were also prepared by spiking ABT-578 into rabbit whole blood. These blood QC samples were used to confirm the validity of the calibration curve. A lower limit of quantitation of 0.050 ng/mL was achieved. The linear dynamic range of blood standards was from 0.050-30.3 ng/mL with the correlation coefficient (r) ranging from 0.9969-0.9996. Overall %CV was between 1.3 and 7.0%, and analytical recovery was between 98.2 and 105.8% for blood QC samples. The %CVs for tissue QC samples were between 6.7 and 13.0%, and analytical recovery after correction was between 93.5 and 114.3%.

Algorithms↗
PubMed2004

Robust simple sequence repeat markers for spruce (Picea spp.) from expressed sequence tags.

Traditionally, simple sequence repeat (SSR)markers have been developed from libraries of genomic DNA. However, the large, repetitive nature of conifer genomes makes development of robust, single-copy SSR markers from genomic DNA difficult. Expressed sequence tags (ESTs), or sequences of messenger RNA, offer the opportunity to exploit single, low-copy, conserved sequence motifs for SSR development. From a 20,275-unigene spruce EST set, we identified 44 candidate EST-SSR markers. Of these, 25 amplified and were polymorphic in white, Sitka, and black spruce; 20 amplified in all 3 spruce species tested; the remaining five amplified in all except one species. In addition, 101 previously described spruce SSRs (mostly developed from genomic DNA), were tested. Of these, 17 amplified across white,Sitka, and black spruce. The 25 EST-SSRs had approximately 9% less heterozygosity than the 17 genomic-derived SSRs (mean H=0.65 vs 0.72), but appeared to have less null alleles, as evidenced by much lower apparent inbreeding (mean F=0.046 vs 0.126). These robust SSRs are of particular use in comparative studies,and as the EST-SSRs are within the expressed portion of the genome, they are more likely to be associated with a particular gene of interest, improving their utility for quantitative trait loci mapping and allowing detection of selective sweeps at specific genes.

Base Sequence↗