[Research advances on improving the therapeutic efficacy of mesenchymal stem cell-derived exosomes in wound repair].

How to promote high-quality wound healing is a common problem for plastic surgery and burn physicians. In recent years, numerous animal studies have demonstrated that mesenchymal stem cell-derived exosomes promote wound repair through multiple mechanisms and are promising cell-free therapeutic agents with broad prospect of application. How to enhance the therapeutic efficacy of exosomes, optimize their drug delivery strategy, and improve their biological properties are the challenges to be overcome in order to move from basic research to clinical application of exosome therapy for wound repair. This article focuses on methods to improve the wound repair potential of mesenchymal stem cell-derived exosomes, and reviews the recent research advances on improving the therapeutic efficacy of mesenchymal stem cell-derived exosomes in wound repair from three aspects, including pretreatment of parental mesenchymal stem cells, hydrogel bio-scaffold loaded with exosomes, and engineered exosomes, to provide a reference for further clinical studies.

Infestation and distribution of chigger mites on Brown rat (Rattus norvegicus) in Yunnan Province, Southwest China.

Chigger mites is a group of arthropods and some of them are vectors of scrub typhus. As a common synanthropic rodent species, the Brown rat (Rattus norvegicus) often harbors lots of ectoparasites including chigger mites. According to some "data mining" strategies, the present study took the advantage of the abundant original data from a long-term field ecological investigation between 2001 and 2015 to make a detailed analysis of chigger mites on R. norvegicus in Yunnan Province, Southwest of China. From 18 of 33 investigated counties, only 1414 chigger mites were collected from 1113 Brown rats with relatively low infestations. The 1414 individual chigger mites were identified as comprising 61 species, 11 genera and 2 subfamilies of the family Trombiculidae with a high species diversity (S=61, H'=3.13). Of 61 mite species, there were four main species, Walchia ewingi, Ascoschoengastia indica, W. koi and A. rattinorvegici, which accounted for 44.41% of the total mites. All the chigger mites were of aggregated distribution among different individuals of R. norvegicus. The Brown rats in the outdoor habitats harbored much more individuals and species of chigger mites with a higher mean abundance (MA=1.46) and mean intensity (MI=12.53) than in the indoor habitats (P<0.05). The overall infestation of the rats was significantly higher in the mountainous landscapes than in the flatland landscapes (P<0.001). The species similarity (Css) of the mites on the male and female rats reached 64.44% with sex biased infestations. The male rats harbored more species and individuals of the mites than the female rats. The adult rats harbored more species and individuals of the mites than the juvenile rats. The species abundance distribution of the mites was successfully fitted by Preston's lognormal model with s(R)=15e-[0.31(R-1)]2 (α=0.31, R2=0.95). On the basis of fitting the theoretical curve by Preston's model, the total mite species on R. norvegicus was estimated to be 86 species, and 25 rare mite species were missed in the sampling field investigation. The curve tendency of the species-plot relationship indicates that R. norvegicus have a great potential to harbor many species of chigger mites, and more species of the mites would be collected if more rats are sampled.

[The role and mechanism of human trophoblastic cell surface antigen 2 in the invasion and metastasis of ovarian cancer].

Objective: To explore the role and molecular mechanism of trophoblastic cell surface antigen 2 (Trop2) in the invasion and migration of ovarian cancer. Methods: Through the data mining of Cancer Cell Line Encyclopedia and TCGA database, the clinical significance of Trop2 expression was analyzed. Western blot was used to detect Trop2 protein expression in ovarian cancer cell lines including A3O, A1780 and SKOV3. SKOV3 cells were used to construct Trop2-short hairpin RNA (shRNA) cell model. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to detect the SKOV3 mRNA expression in SKOV3-shRNA and SKOV3-NC cells. Cell counting kit-8 (CCK8) was used to detect the proliferation of SKOV3-shRNA cells and SKOV3-NC cells. Flow cytometry was used to detect cell cycle and apoptosis in two groups of cells. Transwell array was used to detecte the invasion and migration of SKOV3-shRNA cells and SKOV3-NC cells. Western blot was used to detect the protein expressions of AKT, p-AKT, ß-catenin, caspase3, bcl-2, E-cadherin and vimentin. Results: Trop2 mRNA highly expressed in ovarian cancer, and was related to the tumor stage and patient survival. Compared with A3O cells, Trop2 overexpressed in A1780 and SKOV3 cells (P<0.05). The relative expression levels of Trop2 mRNA in SKOV3-NC group and SKOV3-shRNA group were 1.18±0.24 and 0.42±0.08, with statistically significant difference (P<0.05). The results of CCK-8 array showed that the cell viability of SKOV3-NC group was significantly higher than that of SKOV3-shRNA group (P<0.05). The proportion of G(0)/G(1) cells in SKOV3-NC and SKOV3-shRNA groups were (38.67±4.22)% and (60.24±8.17)%, respectively. G(0)/G(1) arrest was observed in SKOV3-shRNA cells (P<0.05). The apoptosis rate of SKOV3-shRNA group was (26.32±1.81)%, significantly higher than (6.54±1.32)% of SKOV3-NC group (P<0.05). The number of migrating SKOV3 cells in the SKOV3-shRNA and SkOV3-NC groups were 1 255.83±108.44 and 1 679.71±213.92, while the number of invading cells were 242.49±52.09 and 473.54±73.11, respectively. Compared with the SKOV3-NC group, the number of migrating and invading SKOV3-shRNA group was significantly reduced (all P<0.05). The expressions of p-AKT2, Bcl-2, vimentin and ß-catenin were down-regulated, and the expressions of caspase 3 and E-cadherin were up-regulated in SKOV3-shRNA cells. There was no significant change in the total protein level of AKT. Conclusions: Trop2 expression is related to ovarian cancer stage and postoperative survival. Trop2 can promote ovarian cancer cell proliferation and metastasis by activating the AKT/ß-catenin signaling pathway and knockdown of Trop2 inhibits the progression of ovarian cancer.

[Progress of researches on serine protease inhibitors for zoonotic cestode family Taeniidae].

Serine protease inhibitor, a protein superfamily that inhibits the serine protease activity, protects hosts from parasitic infections. This review describes the spatial structure and classification of serine protease inhibitor, mechanisms underlying the interplay between serine protease inhibitor and host immune responses and current advances in serine protease inhibitor of zoonotic cestode family Taeniidae, so as to provide insights into the diagnosis of zoonotic tapeworm infections, discovery of therapeutic targets and screening of vaccine candidates.

Infestation and distribution of chigger mites on Brown rat (Rattus norvegicus) in Yunnan Province, Southwest China

@#Chigger mites is a group of arthropods and some of them are vectors of scrub typhus. As a common synanthropic rodent species, the Brown rat (Rattus norvegicus) often harbors lots of ectoparasites including chigger mites. According to some “data mining” strategies, the present study took the advantage of the abundant original data from a long-term field ecological investigation between 2001 and 2015 to make a detailed analysis of chigger mites on R. norvegicus in Yunnan Province, Southwest of China. From 18 of 33 investigated counties, only 1414 chigger mites were collected from 1113 Brown rats with relatively low infestations. The 1414 individual chigger mites were identified as comprising 61 species, 11 genera and 2 subfamilies of the family Trombiculidae with a high species diversity (S=61, H’=3.13). Of 61 mite species, there were four main species, Walchia ewingi, Ascoschoengastia indica, W. koi and A. rattinorvegici, which accounted for 44.41% of the total mites. All the chigger mites were of aggregated distribution among different individuals of R. norvegicus. The Brown rats in the outdoor habitats harbored much more individuals and species of chigger mites with a higher mean abundance (MA=1.46) and mean intensity (MI=12.53) than in the indoor habitats (P<0.05). The overall infestation of the rats was significantly higher in the mountainous landscapes than in the flatland landscapes (P<0.001). The species similarity (Css) of the mites on the male and female rats reached 64.44% with sex biased infestations. The male rats harbored more species and individuals of the mites than the female rats. The adult rats harbored more species and individuals of the mites than the juvenile rats. The species abundance distribution of the mites was successfully fitted by Preston’s lognormal model with S

[Construction of urban scale-free network model and its epidemiological significance in the prevention and control of COVID-19].

COVID-19 is a public health emergency currently. In this study, a scale-free network model is established based on the Spring Migration data in 2020.The cities is clustered into three different modules. The epidemic of the cities in the black module was the most serious, followed by the red and the cyan. The black module contains 9 cities in Zhejiang province and 8 cities in Guangdong province, most of them located in the southeast coastal economic belt. These cities should be the key cities for epidemic prevention and control.

[Effects of different ages and body mass index on embryo development time kinetic parameters and embryo development potential].

Objective: To investigate the effects of age and body mass index (BMI) on embryo development time kinetic parameters, embryo development potential and clinical pregnancy outcomes. Methods: A retrospective study was conducted to analyze the data of 6 294 embryos from 832 patients who underwent in vitro fertilization and embryo transfer (IVF-ET) in the Reproductive Medicine Center of the First Affiliated Hospital of Zhengzhou University from September 2016 to November 2018. According to the age, they were divided into two groups:<35-year-old group (655 cases, 5 076 embryos), ≥35-year-old group (177 cases, 1 218 embryos). According to the BMI, they were divided into three groups: low body mass group (BMI<18.5 kg/m(2), 47 cases, 355 embryos), normal body recombination (18.5-23.9 kg/m(2), 517 cases, 3 813 embryos), hyperrecombination (BMI>23.9 kg/m(2), 268 cases, 2 126 embryos). Embryo development time kinetic parameters, embryo development potential and clinical pregnancy outcomes in each group were compared. Results: Embryo development to 3 cells, 4 cells were faster in <35-year-old group than in ≥35-year-old group. The blastocyst formation rate, high-quality blastocyst formation rate, pregnancy rate, implantation rate, delivery rate, live birth rate, and abortion rate were all statistically significant (all P<0.05). There were no significant differences in normal fertilization rate, cleavage rate, embryo utilization rate, high quality embryo rate, pregnancy rate, implantation rate, abortion rate, delivery rate, live birth rate between the three BMI groups (all P>0.05). Conclusions: The age has an effect on the partial embryo development time kinetic parameters, but BMI has a little effect on it.

[Prediction of clinical outcomes of patients with surplus cleavage-stage embryos for blastocyst culture after D3 embryo transfer].

Objective: To find the best strategy of embryo transfer, so as to provide theoretical basis for improving the clinical outcomes of in vitro fertilization-Embryo transfer (IVF-ET), we investigate the blastocyst culture of surplus cleavage-stage embryos after D3 embryo transfer and the prediction of clinical outcomes with or without blastocyst formation. Methods: A retrospective study was conducted on 3 568 patients who underwent IVF-ET in the Reproductive Medicine Center of the First Affiliated Hospital of Zhengzhou University from January 2016 to May 2018, whotransplanted two embryos in D3 with blastocyst culture of surplus cleavage-stage embryos, according to their age, they were divided into three groups: <35 years old group, 35-38 years old group, and>38 years old group.And according to the presence or absence of blastocyst formation, they were also divided into two subgroups: blastocyst formation group and non-blastocyst formation group. The embryo development and clinical outcomes in each group were compared. Results: (1) Comparisons of the embryo development in the three age groups with the first cycle. The total fertilization rate, cleavage rate and high quality embryo rate of the blastocyst formation group in the three groups were higher than those in the non-blastocyst formation group, P<0.05; In<35 years old group, the embryo utilization rate (75.0% vs 70.6%), pregnancy rate (74.9% vs 70.3%), planting rate (53.6% vs 48.6%), delivery rate (66.7% vs 61.1%) and live birth rate (66.5% vs 61.0%) of the blastocyst formation group were higher than those in the non-blastocyst formation group, P<0.05. (2) Comparisons of embryo development in the three age groups with multiple cycles (≥2 cycles). In<35 years old group, the total fertilization rate (75.0% vs 70.6%),delivery rate (62.7% vs 43.8%) and live birth rate (62.7% vs 43.8%) of the blastocyst formation group were significantly higher than those in the non-blastocyst formation group, P<0.05; In>38 years old group, the pregnancy rate (56.3% vs 25.8%), implantation rate (34.4% vs 14.5%), delivery rate (43.8% vs 11.3%), live birth rate (43.8% vs 11.3%) of the blastocyst formation group were higher than those in the non-blastocyst formation group, P<0.05. Conclusions: The results of blastocyst culture in different groups can predict the outcomes of embryo transfer in D3. For patients<35 years old with the first cycle, the clinical outcomes of the blastocyst formation group after D3 embryo transfer is better than that of the non-blastocyst formation group. For Patients with multiple cycles (≥2 cycles),the clinical outcomes of the embryo formation group is superior to that of the non-blastocyst formation group<35 years old or>38 years old.

Long-term outcome of telbivudine versus entecavir in treating higher viral load chronic hepatitis B patients without cirrhosis.

Chronic hepatitis B (CHB) patients with higher hepatitis B virus (HBV) load (higher viral load [HVL], HBV DNA ≥1 × 107 copies/mL) require antiviral therapy, but data for evaluating the long-term outcome of this therapy with antiviral agents remain limited. We comparatively evaluated the efficacy and the safety of nucleoside analogues in 179 noncirrhotic CHB patients with HVL over 5 years. The HBeAg-positive (n = 104) or HBeAg-negative (n = 75) patients were treated consecutively with telbivudine (LdT, n = 88) or entecavir (ETV, n = 91) and evaluated for viral response, drug resistance and safety. HBV DNA, viral serology, biochemistries, HBV mutation and off-therapy relapse were determined. The cumulative rates of HBV DNA negativity were 86.4% and 94.5% for LdT and ETV at year 5, respectively. The rates of early viral response (EVR, HBV DNA <103 copies/mL at month 6) under LdT and ETV treatments were 58.0% and 34.1%, respectively (P < .05). Hepatitis B e antigen (HBeAg) and Hepatitis B surface antigen (HBsAg) loss-seroconversions were 47.7% and 18.2% on LdT and 16.5% and 2.2% on ETV (P < .01). Eighteen patients (age 28.2 ± 3.1) experienced HBsAg loss-seroconversion, followed by 33 ± 4.6 month off-therapy without a relapse. Viral mutations and serum creatine kinase elevation were 9.1% and 8.0% on LdT, but only 1.1% and 0% on ETV. Both LdT and ETV suppressed HBV replication in HVL CHB patients within 5 years. LdT therapy achieved a higher EVR, HBeAg and HBsAg seroconversion, especially in the younger patients, whereas ETV caused lower drug resistance and fewer adverse events. This finding might help to identify the optimal treatment for CHB patients with HVL.

MR-safe personal radiation dosimeters.

Magnetic resonance imaging (MRI) is being rapidly integrated for cancer treatments-such systems are referred to as MRI-guided radiation therapy (MRIgRT). As the magnet of an MRI scanner is always on, the presence of a strong static magnetic field from the MRI scanner during radiotherapy delivery presents new challenges. One of the challenges is that a personal radiation dosimeter used to estimate the radiation dose deposited in an individual wearing the device must be MR-safe. No such devices, however, are currently available. In this work we first modified an existing personal dosimeter (by removing a metal clip) to make it MR-safe and then investigated potential effects of magnetic field on dosimeter readings, i.e., optically stimulated luminescent dosimeter (OSLD) readings. We found that the effect of magnetic field on OSLD sensitivity was within radiation protection tolerance levels. OSLD personal dosimeters can be directly used in conjunction with MRIgRT radiation protection purposes.

Analysis of ectoparasites (chigger mites, gamasid mites, fleas and sucking lice) of the Yunnan red-backed vole (Eothenomys miletus) sampled throughout its range in southwest China.

The Yunnan red-backed vole Eothenomys miletus (Rodentia: Cricetidae) is an endemic rodent species and reservoir host of zoonoses in southwest China. Based on a large host sample (2463 voles collected from 39 localities between 2001 and 2013), a general analysis of four categories of ectoparasite (fleas, sucking lice, chigger mites and gamasid mites) on E. miletus across its entire range of distribution was made. This analysis identified a total of 71 895 ectoparasites belonging to 320 species (30 species of flea, 9 of sucking louse, 106 of gamasid mite and 175 of chigger mite) with a high prevalence (87%), mean abundance (29.19) and mean intensity (33.69). Of the 18 vector species of zoonoses found on E. miletus, the flea Ctenophthalmus quadratus (Siphonaptera: Hystrichopsyllidae) and chigger mite Leptotrombidium scutellare (Trombidiformes: Trombiculidae) were the dominant species; these are the main vectors of zoonoses in China. All of the dominant parasite species showed an aggregated distribution pattern. Male voles harboured more species of parasite than females. Chigger mites represented the most abundant species group on voles and their prevalence was positively correlated with mean abundance (r = 0.73; P < 0.05). As a single rodent species, E. miletus has a high potential to harbour abundant ectoparasites with high species diversity and high rates of infestation. The sex of the vole affects ectoparasite infestation.

Effects of early-cleavage embryo transfer on in vitro fertilization-embryo transfer pregnancy outcomes.

PURPOSE: To observe the effects of early-cleavage embryo transfer (ET) on pregnancy outcomes in vitro fertilization-embryo transfer (IVF-ET). MATERIALS AND METHODS: The data of 6,548 two pro-nucleate (2PN) embryos and 968 patients who underwent IVF or intracytoplasmic sperm injection (ICSI) were analyzed. Of the 968 cycles, early-cleavage embryos were used in 432 cycles (early-cleavage group), late-cleavage embryos were used in 246 cycles (late-cleavage group), and both early and late-cleavage embryos were used in 290 cycles (mixed group). RESULTS: High-quality embryo rate was significantly higher in early-cleavage group than in late-cleavage group (82.74% vs 59.83%; p < 0.01). Both clinical pregnancy and implantation rates in IVF or ICSI were significantly higher in early-cleavage group than in late-cleavage group (all p < 0.01). In ICSI, both clinical pregnancy and implantation rates were significantly higher in mixed group than in late-cleavage group (all p < 0.05). CONCLUSION: Early-cleavage ET can improve pregnancy outcomes in IVF or ICSI.

SU-E-T-321: Dynamic Modulated Brachytherapy.

PURPOSE: We introduced the concept of Dynamic Modulated Brachytherapy (DMBT) for rectal cancer, last year. To continue our work, we studied different shield designs and investigated the system's tolerance against systematic setup errors. METHODS: As previously presented, our system uses a cylindrical tungsten shield to create a directional radiation profile, which is modulated through translation and rotation using a specialized robotic arm. We used Monte Carlo simulations and an in-house gradient projection optimization algorithm to look at key design parameters. First, we used ideal phantoms to study treatment quality from shield radii ranging 0.5-1.5 cm in 0.25 cm increments. Second, using 36 patient plans, the dependence on radial source position within the shield was studied. We also analyzed the tolerance of the system to systematic setup errors by simulating dose distributions from possible inaccuracies. These included translational and rotational errors as well as possible Ir-192 source misplacements by the afterloading system. RESULTS: Changes in shield radius followed steady patterns. Increasing the radius showed a consistent increase in dose conformality to the tumor volume and better sparing to surrounding tissues. However, there was also a linear increase in total dwell time. There was a trade off to changing the radial position of the source. As the source is brought away from the center, there is a decrease in conformality to the tumor volume, but sparing to healthy tissues was increased and there is a decrease in total dwell time. We found that any potential setup errors for our system, within anticipated margins, had negligible effects on the dose distributions (< 3% deviation). CONCLUSION: Various parameters for shield designs must be balanced for an effective DMBT application. It was found that the system is highly robust against systematic setup uncertainties.

Controllable dimension of ZnO nanowalls on GaN/c-Al2O3 substrate by vapor phase epitaxy method.

Vertically well-aligned ZnO nanowalls were successfully synthesized at 950-1050 degrees C. Ar gas was introduced into the furnace at a flow rate of 2000-2500 sccm. An Au thin film with a thickness of 3 nm was used as a catalyst. The ZnO nanowalls were successfully grown on the substrate and most of them had nearly the same thickness and were oriented perpendicular to the substrate. The morphology and chemical composition of the ZnO nanowalls were examined as a function of the growth conditions examined. It was found that the grown ZnO nanowalls have a single-crystalline hexagonal structure and preferred c-axis growth orientation based on the X-ray diffraction and high-resolution transmission electron microscope measurements. The room temperature photoluminescence showed a strong free-exciton emission band with negligible deep level emission, indicating the high optical property of our ZnO nanowall samples.

Expression of receptor-binding cancer antigen expressed on SiSo cells and estrogen receptor subtypes in the normal, hyperplastic, and carcinomatous endometrium.

The objectives were to study the expression of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) and estrogen receptor (ER) subtypes in the normal, hyperplastic, and carcinomatous endometrium and to explore their possible role in carcinogenesis and progression of endometrial carcinoma. Immunohistochemistry and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) were applied to detect protein and messenger RNA expression of RCAS1, ER-alpha, and ER-beta in normal, hyperplastic, and carcinomatous endometrium. Western blotting was also used to detect the RCAS1 protein expression. Immunohistochemistry showed that the high expressions of RCAS1 protein were 0% (0/20), 9.1% (2/22), 40% (8/20), and 68.0% (34/50) in normal, simple, and complex hyperplasia, atypical hyperplasia, and endometrial carcinoma, respectively. There was a significant difference between each group (P < 0.05). The high-level expression of RCAS1 was detected more frequently in endometrial cancer with deep myometrial invasion, vascular invasion, and positive ER-alpha (P < 0.05). Two staining patterns of RCAS1 were observed. All normal, simple, and complex hyperplastic endometrium showed P pattern, while all malignant endometrium were of the D pattern. In atypical endometrium, 25% (5/20) cases showed D pattern. The Western blotting and RT-PCR results correlated with the immunohistochemistry results. The expression and distribution of RCAS1 may be involved in the malignant transformation of endometrium, and RCAS1 coexpression with ER-alpha may be associated with development and metastasis of endometrial carcinoma.

The role of PDR13 in tolerance to high copper stress in budding yeast.

PDR13 in Saccharomyces cerevisiae contributes to drug resistance via sequential activation of PDR1 and PDR5. In this study, we found that a PDR13 deletion mutant was hypersensitive to Cu(2+) compared to the wild-type counterpart. The Cu(2+) tolerance mechanism mediated by Pdr13 does not seem to involve Pdr1 or Pdr5, since mutants harboring a deletion of either the PDR1 or PDR5 gene did not show elevated Cu(2+) sensitivity. Instead, we found that the PDR13 null mutant could not express CUP1 or CRS5 metallothionein at wild-type levels when subjected to high Cu(2+) stress. These results suggest that Pdr13 contributes to high Cu(2+) tolerance of S. cerevisiae, at least in part, via a mechanism involving metallothionein expression.

Identification of rice varieties with high tolerance or sensitivity to lead and characterization of the mechanism of tolerance.

Pb inhibits plant growth. To study Pb tolerance in rice (Oryza sativa), we screened 229 varieties for Pb tolerance or sensitivity. Three-day-old seedlings were treated for 12 d with 20 microM Pb solution. Based on the dry weight of the root, three Pb-tolerant (var CH-55, var KH-2J, var Kumnung) and three Pb-sensitive (var Aixueru, var C-9491, var Milyang23) rice varieties were selected. The root biomasses of the tolerant varieties were approximately 10-fold higher than those of the sensitive ones. The greatest morphological difference between the two groups was in the growth of the adventitious roots, as tolerant lines were able to develop adventitious roots after 6 d of Pb treatment, whereas sensitive ones did not develop any even after 15 d. The growth of adventitious roots in the tolerant varieties was dependent on a mechanism, whereby Pb was altered to a form that cannot be taken up by the tissue, because (a) the solution in which the tolerant varieties of rice had grown still contained Pb but nevertheless did not affect the root growth of new rice seedlings, and (b) the adventitious roots of tolerant seedlings developed in Pb solution contained little Pb. The oxalate content in the root and root exudate increased upon Pb treatment in the tolerant varieties, whereas the opposite was observed for the sensitive ones. Oxalate added to the growth solution ameliorated the inhibition of root growth by Pb. These results suggest that compounds such as oxalate secreted from the root may reduce the bio-availability of Pb, and that this may constitute an important Pb tolerance mechanism in the tolerant rice varieties studied here.

Expression of a gibberellin-induced leucine-rich repeat receptor-like protein kinase in deepwater rice and its interaction with kinase-associated protein phosphatase.

We identified in deepwater rice (Oryza sativa L.) a gene encoding a leucine-rich repeat receptor-like transmembrane protein kinase, OsTMK (O. sativa transmembrane kinase). The transcript levels of OsTMK increased in the rice internode in response to gibberellin. Expression of OsTMK was especially high in regions undergoing cell division and elongation. The kinase domain of OsTMK was enzymatically active, autophosphorylating on serine and threonine residues. A cDNA encoding a rice ortholog of a kinase-associated type 2C protein phosphatase (OsKAPP) was cloned. KAPPs are putative downstream components in kinase-mediated signal transduction pathways. The kinase interaction domain of OsKAPP was phosphorylated in vitro by the kinase domain of OsTMK. RNA gel-blot analysis indicated that the expression of OsTMK and OsKAPP was similar in different tissues of the rice plant. In protein-binding assays, OsKAPP interacted with a receptor-like protein kinase, RLK5 of Arabidopsis, but not with the protein kinase domains of the rice and maize receptor-like protein kinases Xa21 and ZmPK1, respectively.

Identification and characterization of 14 transposon-like elements in the noncoding regions of members of the Xa21 family of disease resistance genes in rice.

The rice disease resistance gene Xa21, which encodes a receptor-like kinase, is a member of a multigene family. Based on comparisons of genomic sequences of seven family members, seventeen transposon-like elements were identified in the 5' and 3' flanking regions and introns of these genes. Sequence characterization revealed that these elements are diverse, showing similarity to maize Ds, CACTA and miniature inverted repeat-like elements, as well as novel elements. Only two elements were located in presumed coding regions, indicating that integration of transposable elements at the Xa21 disease resistance locus occurred preferentially in noncoding regions.