[Analysis of whole blood cells and genetic influencing factors in medical radiation workers]

Objective: To explore the influencing factors of whole blood cells and genetics of medical radiation workers, and provide technical support for improving occupational health management and strengthening radiation protection. Methods: In January 2022, a total of 4180 medical radiation workers who underwent occupational health examination in Gansu Provincial Center for Disease Control and Prevention from January 2020 to December 2021 were collected as the research objects, and the results of demographic characteristics, whole blood cells, chromosome aberrations, lymphocyte micronucleus and other results were collected. The whole blood cells and genetic abnormalities of different demographic characteristics of medical radiation workers were compared. And the influencing factors of whole blood cells and genetic abnormalities were analyzed by multivariate logistic regression. Results: The rates of hemoglobin (HGB), chromosome aberration and lymphocyte micronucleus abnormality were the highest in the nuclear medicine group, and the rate of white blood cell (WBC) abnormality in the radiotherapy group was higher than those in other occupational groups, the differences were statistically significant (P<0.05). The abnormal rates of WBC, HGB and lymphocyte micronucleus in female radiation workers were significantly higher than those in male radiation workers (P<0.001). The abnormal rates of HGB and lymphocyte micronucleus were statistically different among different working years and different age radiation workers (P<0.001). And the abnormal rate of platelet (PLT) was statistically different among different working years radiation workers (P<0.05). The abnormal rate of HGB in radiation workers of different hospital levels was statistically different (P<0.001). Logistic regression analysis showed that the risk of abnormal WBC and HGB in females radiation workers were 3.048 times and 13.122 times of those in males, respectively (P<0.001). The abnormal risks of WBC in the 6-20 working years group and >20 working years group were 1.517 times and 1.874 times of that in the ≤5 working years group, respectively (P<0.05). The abnormal risk of PLT in the >20 working years group was 2.643 times of that in ≤5 working years group (P<0.05). The abnormal risk of WBC in radiotherapy group and intervention group were 2.407 times and 1.341 times of that in general radiotherapy group, respectively (P<0.05) . Conclusion: Ionizing radiation has different effects on the whole blood cells and genetic indexes of workers in the nuclear medicine, interventional group and radiotherapy group. The occupational health protection of female radiation workers should be paid attention to.

[Transcriptomic analysis of tuberculosis peptide-based vaccine MP3RT in humanized mice]

Objective: To identify the differentially expressed genes (DEGs) induced by tuberculosis peptide-based vaccine MP3RT in a humanized mouse model using transcriptomics technology. Methods: This study was conducted from August 2019 to February 2022. We used edgeR software to screen DEGs with a fold change greater than or equal to 1.5 and a P value less than 0.05 as screening conditions. Gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG), and protein interaction network analyses were performed on the screened DEGs. Then, these DEGs were verified by RT-qPCR and statistically analyzed by GraphPad Prism 8 software. Results: A total of 367 DEGs (214 up-regulated and 153 down-regulated) were identified by transcriptomics. Bioinformatics analysis showed that the GO enrichment of the DEGs mentioned above significantly focused on cell metabolism, growth, apoptosis, inflammation, and other terms. In contrast, the KEGG enrichment significantly focused on inflammatory pathways such as the MAPK signaling pathway. Protein interaction network analysis showed that protein Abl1 had the highest aggregation, the highest aggregation coefficient, and the best connectivity. RT-qPCR results showed that gene expressions of cpne4 (t=2.48, P=0.048 0), h2-q10 (t=2.95, P=0.025 6), mef2c (t=2.87, P=0.028 4), cr2 (t=3.23, P=0.178), ablim1 (t=2.91, P=0.033 5), dll1 (t=2.70, P=0.027 3) and ms4a2 (t=3.03, P=0.019 2) genes in the MP3RT group were significantly up-regulated than those in the PBS group, while gene expressions of cd163l1 (t=2.56, P=0.043 0), il1r1 (t=2.91, P=0.022 7) and cd34 (t=2.42, P=0.046 2) genes in the MP3RT group were significantly down-regulated than those in the PBS group. Conclusions: The MP3RT vaccine induced 367 DEGs in humanized mice, which were associated with metabolic and immune responses. Furthermore, we found that p38 MAPK and JNK/MAPK signaling pathways played an important role in the molecular mechanism of the MP3RT vaccine.

[Analysis of the efficacy and safety of low-dose aspirin in preventing renal artery stenosis in kidney transplantation]

Objective: To evaluate the clinical value of aspirin as a prophylactic for transplant renal artery stenosis (TRAS). Methods: From January 2017 to November 2019, clinical data of 307 patients who had undergone renal transplant in Zhengzhou University People's Hospital were collected. Patients were divided into two groups: the treatment group (124 recipients who had taken oral aspirin 100 mg/d after transplant) and the control group (183 recipients who had not taken aspirin after transplant). The general data, incidence of initially diagnosed and confirmed TRAS, type of renal artery anastomosis vessels, duration of stenosis, location of stenosis, and complications were compared between the two groups. The treatment group was further divided into two subgroups, the early group (92 recipients) and the delayed group (32 recipients), according to the time of starting aspirin after operation. Subgroup analysis was performed. Results: Among all 307 patients included, there were 241 males and 66 females, aged 19-64 years. There were no statistical difference between the treatment and control groups in terms of gender, age, comorbidities, number of arterial vessels, type of graft, and acute rejection all P>0.05. Among 46 initially diagnosed TRAS patients, 13 (10.5%) and 33 (18.0%) cases were in the treatment and control group respectively, with no statistically significant difference in stenosis rate (P>0.05). The number of confirmed TRAS patients was 1 (0.8%) and 24 (13.1%) in the treatment and control group respectively, with statistically significant difference in stenosis rate (P<0.001). The proportion of patients with bleeding disorders in the treatment group was slightly higher than that in the control group (13.7% vs 8.7%), and the proportion of infarct diseases was slightly lower than that in the control group (1.6% vs 4.9%). But there was no significant difference in aspirin-related complications between the two groups (P>0.05). Subgroup analysis showed that there was no significant difference in initially diagnosed and confirmed TRAS and aspirin-related complications between the early group and the delayed group (all P>0.05). Conclusions: Oral low-dose aspirin after kidney transplantation can effectively reduce the incidence of TRAS, without increasing the risk of aspirin-related complications.

A machine learning model for predicting the ballistic impact resistance of unidirectional fiber-reinforced composite plate

It has been a vital issue to ensure both the accuracy and efficiency of computational models for analyzing the ballistic impact response of fiber-reinforced composite plates (FRCP). In this paper, a machine learning (ML) model is established in an effort to bridge the ballistic impact protective performance and the characteristics of microstructure for unidirectional FRCP (UD-FRCP), where the microstructure of the UD-FRCP is characterized by the two-point correlation function. The results showed that the ML model, after trained by 175 cases, could reasonably predict the ballistic impact energy absorption of the UD-FRCP with a maximum error of 13%, indicating that the model can ensure both computational accuracy and efficiency. Besides, the model's critical parameter sensitivities are investigated, and three typical ML algorithms are analyzed, showing that the gradient boosting regression algorithm has the highest accuracy among these algorithms for the ballistic impact problem of UD-FRCP. The study proposes an effective solution for the traditional difficulty of the ballistic impact simulation of composites with both high efficiency and accuracy.

MicroRNA-1274a serves as a prognostic biomarker in patients with osteosarcoma and is involved in tumor progression via targeting ADAM9

Osteosarcoma (OS) is the most frequent primary malignancy in bone, and commonly occurs in children and adolescents. The aim of this study was to assess the aberrant expression of miR-1274a in OS patients, and to evaluate the role of miR-1274a as a prognostic biomarker and tumor suppressor in OS progression. miR-1274a expression was estimated using quantitative real-time polymerase chain reaction. The Kaplan-Meier method and Cox regression analysis were used to evaluate the prognostic value of miR-1274a in OS. Gain- and loss-of-function in vitro experiments were used to explore the functional role of miR-1274a in OS progression. A target gene of miR-1274a was analyzed using a dual-luciferase reporter assay. miR-1274a expression was decreased in OS tissues and associated with distant metastasis and clinical stages in OS patients. Low miR-1274a could predict poor overall survival and disease-free survival in OS. The overexpression of miR-1274a could inhibit OS cell proliferation, migration and invasion. Additionally, ADAM9 was demonstrated to serve as a direct target of miR-1274a in OS cells. In conclusion, reduced miR-1274a predicts poor prognosis and serves as a potential tumor suppressor in OS. ADAM9 is a target of miR-1274a, which may mediate the functional role of miR-1274a in OS progression.

First Evidence of Local E×B Drift in the Divertor Influencing the Structure and Stability of Confined Plasma near the Edge of Fusion Devices

The structure of the edge plasma in a magnetic confinement system has a strong impact on the overall plasma performance. We uncover for the first time a magnetic-field-direction dependent density shelf, i.e., local flattening of the density radial profile near the magnetic separatrix, in high confinement plasmas with low edge collisionality in the DIII-D tokamak. The density shelf is correlated with a doubly peaked density profile near the divertor target plate, which tends to occur for operation with the ion B×∇B drift direction away from the X-point, as currently employed for DIII-D advanced tokamak scenarios. This double-peaked divertor plasma profile is connected via the E×B drifts, arising from a strong radial electric field induced by the radial electron temperature gradient near the divertor target. The drifts lead to the reversal of the poloidal flow above the divertor target, resulting in the formation of the density shelf. The edge density shelf can be further enhanced at higher heating power, preventing large, periodic bursts of the plasma, i.e., edge-localized modes, in the edge region, consistent with ideal magnetohydrodynamics calculations.

[Occupational health status about radiation workers from township hospitals in Gansu, China]

Objective: To investigate occupational health status about radiation workers from township hospitals in Gansu, China, and to explore the dose-effect relationship of exposure dose of radiation workers. Methods: A total of 390 X-ray workers from township hospitals in Gansu Province and 450 X-ray workers from the county/district-level hospitals in the county/district where the township hospitals were located were divided into research group and control group. Their workload, radiation protection condition, and occupational health monitoring data were used for impact assessment and risk estimation. Results: The annual workload of radiation workers from township hospitals was 845.33±361.622 people, and that of radiation workers from county/district-level hospitals was 1967.74±762.055 people; there was a significant difference in annual workload between the two groups of subjects (P<0.05) . Indices such as detection rate of lens opacity, detection rate of abnormal platelet count, red blood cell count, and hemoglobin count, micronucleated lymphocyte rate, and chromosome aberration rate were significantly different between the two groups (P<0.05) . Conclusion: Radiation workers from township hospitals suffer from certain radiation damage.

[Study on the relationship between age-related hearing loss and cognitive impairment]

Objective: To investigate the correlation between age-related hearing loss and cognitive impairment. Methods: 201 elderly patients, who were admitted to the Department of Otorhinolaryngology of Peking University People's Hospital from March 1, 2017 to March 31, 2017, were evaluated with hearing screening and the Montreal Cognitive Assessment Scale. Among them, 101 were female and 100 were male, aged 60-90 years old. Taking the cognitive level as the dependent variable, and taking the age, sex, education, occupation, marital status, residence, and average hearing loss (average hearing threshold of 500, 1 000, 2 000, and 4 000 Hz), as well as the length of conscious hearing loss as the independent variables, the single factor analysis and multivariate linear regression analysis were used to screen the main factors affecting the cognitive level of the elderly. Results: Of the 201 elderly patients, 39 had normal hearing, 65 had mild hearing loss, 80 had moderate hearing loss, 16 had severe hearing loss, and 1 had profound hearing loss. The average degree of hearing loss was the influencing factor of cognitive impairment, and it mainly affected the directional force and abstract ability in the cognitive domains (P<0.05); The age, self-reported hearing loss, years of education, marital status, past ear diseases, and hypertension were relatively independent factors that affected the cognitive level(P<0.05). Conclusions: Age-related hearing loss is the risk factor for the cognitive impairment, especially for abstraction and orientation, in the elderly. The self-reported hearing loss is an independent risk factor for cognitive impairment.

[Analysis of nystagmus and medical history of 121 patients positive with positional test]

Objective: To observe the characteristics of positional nystagmus and clinical profile of patients with positive positional test, and to explore its possible pathogenesis.Method: One hundred and twenty-one patients with positive positional test in the vestibular function examination were enrolled in the Peking University International Hospital from January to June in 2017. According to the 2017 BPPV guidelines, patients with test positive positional nystagmus were divided into two groups: definite BPPV and the controversial syndrome. Analyses of gender, age and characteristics of nystagmus, with or without recurrent dizziness, headache, and motion sickness were undertaken between the two groups, as well as response to the repositioning maneuver. Result: Of the total 121 cases, 49 cases were diagnosed as definite BPPV, accounting for 40.5%, 72 cases as controversial syndrome, accounting for 59.5%. The proportion of women in the two group was 76.2% and 78.9%, respectively. The average age of definite BPPV and the controversial syndrome was 51.2±16.8 and 51.3±15.7, respectively.There were significant differences in nystagmus duration, spontaneous nystagmus and nystagmus after headshaking between the two groups by chi square test(P<0.01). The mean intensity of horizontal and vertical nystagmus in posterior semicircular canal BPPV was(10.2±7.4) °/s and(36.6±17.5) °/respectively. And the mean intensity of nystagmus in the strong and weak side in horizontal semicircular canal BPPV was(40.8±25.1) °/s and(20.7±11.1) °/respectively. The intensity of horizontal and vertical nystagmus of the controversial syndrome group was(7.2±7.7) °/s and(7.2±4.3) °/s respectively. The incidence of headache in the controversial syndrome group was significantly higher than that in the BPPV group, P=0.013. According to the guidelines, patients were evaluated one day after the initial treatment. The cure rate and effective rate of the definite BPPV group was 75%(36/48) and 87.5%(42/48),and was 0 and 30.4% in the controversial syndrome group respectively. Conclusion: The patients in controversial syndrome group have a preponderance of exhibiting positive nystagmus during positional test. Nystagmus were usually of low velocity and sustained. Most of these cases presented spontaneous nystagmus and headshaking induced nystagmus, as well as headache and lacunar infarctions in history, and the response to the repositioning maneuver were often poor. It may be related to vestibular migraine and central nervous system. The diagnosis of BPPV must be prudent.Both characteristics of nystagmus and medical history should be carefully analyzed to avoid overdiagnosis.

[The investigation rate and influence factors of tinnitus with chronic suppurative otitis media]

Objective:To investigate the incidence of tinnitus and its influencing factors in patients with chronic suppurative otitis media, and to provide clinical data for the study of the pathogenesis of tinnitus.Method:The clinical data of 77 patients with chronic suppurative otitis media who underwent modified radical mastoidectomy and tympanoplasty were investigated. When tinnitus and otitis media happened in the same side,then the tinnitus is judged to be otitis media related. Patients were further divided into otitis media related tinnitus and the no tinnitus groups. The differences of tinnitus severity, sleep disturbance, migraine (migraine features), snoring and gastroesophageal reflux were compared between the two groups in tinnitus occurrence and classification.Result:The incidence of otitis media related tinnitus was 55.8%(43/77). Most of the tinnitus happened(33/43) later than the occurrence of otitis media for several years or even decades. There were 43 cases of tinnitus associated with otitis media, and 31 cases without tinnitus. Between the groups, significant differences were observed in migraine features, and the P value is 0.011, while no significant differences were noticed in the severity of hearing loss and sleep disorders, snoring, gastroesophageal reflux. Ranking of otitis media related tinnitus was positively related to the degree of hearing loss, especially the bone conduction threshold. With Spearman rank correlation test,P values of mean value(250Hz,500Hz,1kHz,2kHz,4kHz), middle frequency (1kHz, 2kHz)and high frequency (4kHz) of bone conduction threshold were 0.010,0.019 and 0.003, and the correlation coefficients were 0.391,0.356 and 0.443, respectively.Conclusion:The occurrence of tinnitus in patients with otitis media may not be consistent with the time of otitis media, and theoretically later than the occurrence of otitis media is more reasonable. Whether tinnitus occurs in patients with otitis media is not related to sleep disorders, the degree of air conduction and bone conduction hearing loss, but is related to migraine features. The severity of tinnitus associated with otitis media is associated with bone conduction hearing loss.

[Relevant factors of tinnitus in the elderly: an analysis of 150 volunteers]

Objective:To evaluate and characterize tinnitus in elderly volunteers，try to find out the relevant factors that can affect the incidence of tinnitus.Method:The study included 150 elderly volunteers. All volunteers had taken the otology examination and pure tone audiometry. They were interviewed by the investigators who were trained together, using the same questionnaire. The characteristics of tinnitus and the relationship between all relevant factors and tinnitus were analyzed.Result:Average age was 71.4 years. There are now 77 patients with tinnitus(51.3%), of which 31 cases have sustained tinnitus for more than 3 months, accounting for 40.3% of existing tinnitus volunteers. There was negative correlation between tinnitus and age. There was positive correlation between tinnitus and hearing loss. Tinnitus and headache had no correlation(P>0.05).Conclusion:After reach a certain age(70 years old), the incidence of tinnitus decreased. Hearing loss might be the most dangerous factor.If the hearing loss was more serious, the incidence of the tinnitus became higher. Tinnitus in the elderly may be the result of a combination of factors.

The Hierarchy of Proinflammatory Cytokines in Ocular Inflammation

PURPOSE

The concept of tissue-dependent cytokine hierarchy has been demonstrated in a number of diseases, but it has not been investigated in ophthalmic diseases. Here, we evaluated the functional hierarchy of interleukin-1β (IL-1β), IL-6, IL-17A, and tumor necrosis factor (TNF) in the induction of ocular inflammation.

MATERIALS AND METHODS

We delivered adeno-associated virus (AAV) vectors expressing IL-1β, IL-6, IL-17A, or TNF intravitreally in naïve C57/BL6 mice and compared and contrasted the inflammatory effects in the eye 5 weeks after AAV-mediated gene transfer. We also used an in vitro human system to test the effect of cytokines on barrier function.

RESULTS

We found that IL-1β had the highest ability to initiate ocular inflammation. The continuous overexpression of IL-1β resulted in a significant upregulation of additional proinflammatory mediators in the eye. Using scanning laser ophthalmoscope and optical coherence tomography imaging techniques, we showed that a low dose of AAVIL-1β was sufficient and was as pathogenic as a high dose of TNF in inducing vascular leakage, retinal degeneration, and cellular infiltration. Furthermore, only a marginal increase in IL-1β was enough to cause cellular infiltration, thus confirming the highly pathogenic nature of IL-1β in the eye. Contrary to our expectation, IL-6 or IL-17A had minimal or no effect in the eye. To examine the clinical relevance of our findings, we used an impedance assay to show that IL-1β alone or TNF alone was able to cause primary human retinal endothelial cell barrier dysfunction in vitro. Again, IL-6 alone or IL-17A alone had no effect on barrier function; however, in the presence of IL-1β or TNF, IL-17A but not IL-6 may provide additive proinflammatory effects.

CONCLUSIONS

Our studies demonstrate the existence of a functional hierarchy of proinflammatory cytokines in the eye, and we show that IL-1β is the most pathogenic when it is continuously expressed in the eye.

Factors associated with Staphylococcus aureus nasal carriage and molecular characteristics among the general population at a Medical College Campus in Guangzhou, South China

BACKGROUND

The nasal cavity is the main colonization site of Staphylococcus aureus (S. aureus) in human body. Nasal carriage may be a strong risk factor for some serious infection. There was still limited information about the nasal carriage for S. aureus in south China.

METHODS

Sought to determine the prevalence and molecular characteristics of S. aureus nasal carriage, 295 volunteers residing on a medicine campus were investigated and sampled the nasal cavity swab. Selected S. aureus isolates were carried through molecular analysis, including pulsed-field gel electrophoresis (PFGE), multilocus sequence analysis, staphylococcal cassette chromosome mec (SCCmec) and virulence gene detection.

RESULTS

A total of 73 S. aureus isolates were recovered from separate subjects (24.7%, 73/295), with one methicillin-resistant S. aureus (MRSA) isolate (0.3%, 1/295). Among the 73 isolates, 71 isolates were successfully grouped into 13 pulsotypes by PFGE analysis, with profiles A and L the most prevalent; 12 sequence types (STs) were found among the 23 isolates which had similar drug resistant spectrum. ST59, ST188 and ST1 were the most prevalent, accounting for 17.4, 13.0 and 13.0% of all isolates, respectively. The MRSA isolate presented ST8-SCCmec III. 56.5% of isolates carried both the staphylococcal enterotoxin A (sea) and enterotoxin B (seb) genes. 83.6% of the S. aureus isolates were resistant to penicillin, all isolates were susceptible to quinupristin/dalfopristin, levofloxacin, teicoplanin and vancomycin. The most common risk factors for S. aureus carriage were being male, age ≤30 years, and nasal cavity cleaning habits.

CONCLUSIONS

Colonization by S. aureus was greater among male and young age (20-30 years) students and those with irregularity nasal cleaning. The S. aureus isolates selected were revealed into various sequence types and pulsotypes, indicating molecular heterogeneity among S. aureus isolates from the populations in the medical college in Guangzhou.

A critical study of the generality of the two step two electron pathway for water splitting by application of a C3N4/MnO2 photocatalyst

A novel C3N4-CDot composite photocatalyst was very recently shown to be highly efficient and very stable in water splitting by solar radiation without using any sacrificial reagent (J. Liu, et al., Science, 2015, 347(6225), 970). This photocatalyst utilizes a two-electron/two-step process in which the production of H2O2 and H2 is photocatalyzed by using C3N4 in the first step and H2O2 is decomposed by using CDots in the second step. The present work is a study on the generality of this approach by application of a C3N4/MnO2 catalyst. This new catalyst indeed splits water by a two step process in a stable way, without any sacrificial agent. It was however found that though the absorbance of the new catalyst in the visible range of 500-600 nm is much larger than that of the C3N4-CDot catalyst, its water splitting efficiency is much lower. These findings add insight into and assist in the further optimization of this new class of photocatalysts to meet the requirements of commercial water splitting systems.

Graphene-clad microfibre saturable absorber for ultrafast fibre lasers

Graphene, whose absorbance is approximately independent of wavelength, allows broadband light–matter interactions with ultrafast responses. The interband optical absorption of graphene can be saturated readily under strong excitation, thereby enabling scientists to exploit the photonic properties of graphene to realize ultrafast lasers. The evanescent field interaction scheme of the propagating light with graphene covered on a D-shaped fibre or microfibre has been employed extensively because of the nonblocking configuration. Obviously, most of the fibre surface is unused in these techniques. Here, we exploit a graphene-clad microfibre (GCM) saturable absorber in a mode-locked fibre laser for the generation of ultrafast pulses. The proposed all-surface technique can guarantee a higher efficiency of light–graphene interactions than the aforementioned techniques. Our GCM-based saturable absorber can generate ultrafast optical pulses within 1.5 μm. This saturable absorber is compatible with current fibre lasers and has many merits such as low saturation intensities, ultrafast recovery times, and wide wavelength ranges. The proposed saturable absorber will pave the way for graphene-based wideband photonics.

Low-to-High Confinement Transition Mediated by Turbulence Radial Wave Number Spectral Shift in a Fusion Plasma

A new model for the low-to-high (L-H) confinement transition has been developed based on a new paradigm for turbulence suppression by velocity shear [G. M. Staebler et al., Phys. Rev. Lett. 110, 055003 (2013)]. The model indicates that the L-H transition can be mediated by a shift in the radial wave number spectrum of turbulence, as evidenced here, for the first time, by the direct observation of a turbulence radial wave number spectral shift and turbulence structure tilting prior to the L-H transition at tokamak edge by direct probing. This new mechanism does not require a pretransition overshoot in the turbulent Reynolds stress, shunting turbulence energy to zonal flows for turbulence suppression as demonstrated in the experiment.

Analysis of the drug-resistant characteristics of Klebsiella pneumoniae isolated from the respiratory tract and CTX-M ESBL genes

The main aim of this study was to understand the relationship between the drug-resistant characteristics of Klebsiella pneumoniae and CTX-M-type extended spectrum β-lactamases (ESBLs), and to detect the distributions of CTX-M-type ESBLs in clinically isolated strains. CTX-M ESBL genes isolated from the clinical samples were amplified by polymerase chain reaction and identified by sequence analysis; the antibiotic susceptibility of the samples was determined using the Kirby-Bauer disc-diffusion method. One hundred and five strains among the 246 isolated strains of K. pneumoniae tested positive for ESBL production (42.68%); 92 of these produced CTX-M ESBLs. Of the 92 CTX-M ESBL strains, 81 produced CTX-M-1 ESBLs and 11 produced CTX-M-25 ESBLs. Fifty-seven of the CTX-M-1 ESBL- and six of the CTX-M-25 ESBL-producing bacteria had CTX-M ESBL genes that coexisted in the plasmid and chromosome. The Kirby-Bauer antibiotic susceptibility method revealed that CTX-M ESBL-positive strains showed a higher rate of resistance to cefazolin, cefoxitin, cefuroxime, ceftazidime, cefotaxime, aztreonam, levofloxacin, and cotrimoxazole, compared to the CTX-M ESBL-negative strains (P < 0.05). The CTX-M ESBL genes were commonly observed in the K. pneumoniae isolated from respiratory tract samples; these were significantly associated with the drug-resistant characteristics of K. pneumoniae to β-lactam antibiotics.

FSHR gene Thr307Ala and Asn680Ser polymorphisms in infertile men: an association study in North China and meta-analysis

Male infertility is a complex multifactorial and polygenic disease, and genetic factors play an important role in its formation and development. Recently, the association between follicle stimulating hormone receptor (FSHR) gene polymorphisms and male infertility risk has attracted widespread attention due to the unique biological functions of FSH. The aim of this study was to further explore the associations between the Thr307Ala and Asn680Ser polymorphisms of the FSHR gene and male infertility. A case-control study of 212 infertile and 164 fertile men from North China was performed. FSHR polymorphism genotypes were obtained through direct DNA sequencing. A meta-analysis was also performed. In the single-site association analysis, no significant associations were identified between FSHR Thr307Ala and Asn680Ser polymorphisms and male infertility (P > 0.05). However, we found that the combined genotypic frequency of Thr/Ala + Asn/Asn was higher in infertile patients than in controls (6.6 vs 1.8%; odds ratio (OR) = 3.795; 95% confidence interval (CI): 1.072-13.434, P = 0.027). In the meta-analysis, there was also no evidence of FSHR polymorphism (rs 6165 and rs 6168) association with male infertility (P > 0.05). However, we found that the combined genotypes Thr/Thr + Asn/Asn had an increased risk of male infertility (OR = 1.238; 95%CI: 1.001-1.537, P = 0.049). Our studies further confirmed reports that there were no significant associations between the FSHR Thr307Ala and Asn680Ser polymorphisms and male infertility risk. However, a combined FSHR genotype showed significant association with male infertility.

Neonatal lipopolysaccharide exposure delays puberty and alters hypothalamic Kiss1 and Kiss1r mRNA expression in the female rat

Immunological challenge experienced in early life can have long-term programming effects on the hypothalamic-pituitary-adrenal axis that permanently influence the stress response. Similarly, neonatal exposure to immunological stress enhances stress-induced suppression of the hypothalamic-pituitary gonadal (HPG) axis in adulthood, but may also affect earlier development, including the timing of puberty. To investigate the timing of the critical window for this programming of the HPG axis, neonatal female rats were injected with lipopolysaccharide (LPS; 50 microg/kg i.p.) or saline on postnatal days 3 + 5, 7 + 9, or 14 + 16 and monitored for vaginal opening and first vaginal oestrus as markers of puberty. We also investigated the effects of neonatal programming on the development of the expression patterns of kisspeptin (Kiss1) and its receptor (Kiss1r) in hypothalamic sites known to contain kisspeptin-expressing neuronal populations critical to reproductive function: the medial preoptic area (mPOA) and the arcuate nucleus in neonatally-stressed animals. We determined that the critical period for a significant delay in puberty as a result of neonatal LPS exposure is before 7 days of age in the female rat, and demonstrated that Kiss1, but not Kiss1r mRNA, expression in the mPOA is down-regulated in pre-pubertal females. These data suggest that the mPOA population of kisspeptin neurones play a pivotal role in controlling the onset of puberty, and that their function can be affected by neonatal stress.

Molecular analysis of hormone-regulated petal regeneration in Petunia

The petal is an important floral organ of higher plants. To study the mechanism of petal development, the in vitro regeneration system of petals was established in Petunia. High-frequency induction of petals occurred directly from explants on the media containing the combination of N6-benzyladenine (6-BA) and indole-3-acetic acid (IAA). Expression analysis of genes involved in flower development indicated that these genes were classified into three types. ABERRANT LEAF AND FLOWER (ALF) gene was induced during petal regeneration. Whereas, B-class and E-class genes, and genes involved in cell division were constitutively upregulated. In contrast, C-class and D-class genes were not expressed in explants and regenerated tissues. Further, in situ hybridization analysis showed that both ALF and GREEN PETAL (GP) expression were spatially regulated. The results suggest that differential regulation of gene expression occurs in the presence of hormones during petal regeneration, and hormone-regulated gene expression might be required for petal regeneration. This study provides the preliminary information to understand the mechanism of petal regeneration.

Neonatal lipopolysaccharide exposure exacerbates stress-induced suppression of luteinizing hormone pulse frequency in adulthood

Early life exposure to immunological challenge has programming effects on the adult hypothalamo-pituitary-adrenocortical axis stress responsivity, and stress is known to suppress GnRH pulse generator activity, especially LH pulses. We investigated the effects of neonatal exposure to endotoxin on stress-induced suppression of pulsatile LH secretion and the involvement of corticotropin-releasing factor (CRF) receptor mechanisms in adult rats. Pups at 3 and 5 d of age were administered lipopolysaccharide (LPS, 50 microg/kg, ip). At 12 wk of age, they were ovariectomized and implanted with sc 17beta-estradiol capsules and i.v. cannulas. Blood samples (25 microl) were collected every 5 min for 5 h for LH measurement. After 2 h of sampling, rats were given LPS (25 microg/kg, iv). CRF and CRF-R1 and CRF-R2 receptor mRNA was determined by RT-PCR in medial preoptic area (mPOA) micropunches collected at 3 h after LPS administration. There was no difference in basal LH pulse frequency between neonatal LPS- and neonatal saline-treated controls. However, neonatal endotoxin-treated rats exhibited a significantly greater LPS stress-induced suppression of LH pulse frequency. Basal mPOA CRF-R1 expression was unchanged in neonatal LPS- and neonatal saline-treated rats. However, CRF-R1 expression was significantly increased in response to LPS stress in neonatal LPS-treated animals but not in neonatal saline-treated controls. CRF and CRF-R2 expression was unchanged in all treatment groups. These data demonstrate that exposure to bacterial endotoxin in early neonatal life programs long-term sensitization of the GnRH pulse generator to the inhibitory influence of stress in adulthood, an effect that might involve up-regulation of CRF-R1 expression in the mPOA.

Hypercholesterolemia accelerates vascular calcification induced by excessive vitamin D via oxidative stress

Hypercholesterolemia plays an important role in the initiation and progression of atherosclerosis and has a positive correlation with cardiovascular disease. Calcification is a common feature of atherosclerotic lesions and contributes to cardiovascular dysfunctions. The present study investigated the role of hypercholesterolemia in vascular calcification and its potential mechanism. Models of vascular calcification were established by administering vitamin D2 (VD) to rats alone or combined with a high-cholesterol diet (HCD) and by treating rat aorta smooth muscle cells (RASMCs) with beta-glycerophosphate (GP) alone or combined with oxidized low-density lipoprotein (oxLDL) in vitro. In rats, the combination of VD with HCD significantly enhanced vessel calcium deposition and the activity and mRNA expression of vessel alkaline phosphatase (ALP) compared to treatment with VD alone. This combination also enhanced serum levels of total cholesterol, oxLDL, and malondialdehyde as well as vascular production of superoxide anion, while it reduced the vascular activity of superoxide dismutase. Both simvastatin, a cholesterol-lowering agent, and antioxidant vitamin E antagonized the effects of the above combination. In RASMCs, oxLDL accumulation dependently accelerated calcium deposition in cell layers initiated by GP alone. Also, oxLDL stimulated ALP activity and mRNA expression in RASMCs in a concentration-dependent manner. Taken together, these results suggest that acceleration of vascular calcification by hypercholesterolemia might be attributed to oxidative stress and such calcification may be another target of statin or antioxidant action in antiatherosclerosis.

Rapid analysis of CGG repeat length in the FMR1 gene

The number of trinucleotide CGG repeats at the 5' untranslated region of the FMR1 gene is associated with the fragile X syndrome of mental retardation. We screened for the CGG repeat length in the FMR1 gene of the X-chromosomes from unrelated normal Chinese subjects recruited in Hong Kong and Dalian, a southern and a northern Chinese city respectively. These cities are about 3000 km apart and the residents have few historical interactions. Genomic DNA was analysed by PCR and detected by Southern hybridisation with a radiolabelled (CGG)5 probe for the CGG repeat number. A different distribution pattern of CGG allele size from the Caucasians is observed. It is a bimodal pattern with the most common CGG repeats allele at 29 against 30 in the Caucasians. Among the Hong Kong subjects, five alleles of more than 50 CGG repeats were detected, and four of those were in heterozygous females. There was no difference in the repeat patterns in subjects from the two cities, suggesting no genotypic variation in FMR1 between northern and southern Chinese.

Mouse testis brain ribonucleic acid-binding protein/translin colocalizes with microtubules and is immunoprecipitated with messenger ribonucleic acids encoding myelin basic protein, alpha calmodulin kinase II, and protamines 1 and 2

Testis brain RNA-binding protein (TB-RBP) is a sequence-dependent RNA-binding protein that binds to conserved Y and H sequence elements present in many brain and testis mRNAs. Using recombinant TB-RBP and a highly enriched tubulin fraction, we demonstrate here that recombinant TB-RBP binds to microtubules assembled in vitro. The interaction between recombinant TB-RBP and microtubules was inhibited by high salt and by the microtubule disassembling agents colcemid and calcium, but not by the microfilament-disassembling agent cytochalasin D. Confocal microscopy confirmed colocalization of TB-RBP and tubulin in the cytoplasm of male germ cells. An affinity-purified antibody prepared against recombinant TB-RBP specifically precipitated mRNAs encoding myelin basic protein and alpha calmodulin-dependent kinase II-two transported mRNAs, and protamines 1 and 2-two translationally regulated testicular mRNAs. These data indicate an intracellular association between TB-RBP and specific target mRNAs and suggest an involvement of TB-RBP in microtubule-dependent mRNA transport in the cytoplasm of cells.

Protein-protein interactions between the testis brain RNA-binding protein and the transitional endoplasmic reticulum ATPase, a cytoskeletal gamma actin and Trax in male germ cells and the brain

Numerous functions have been proposed for the testis brain RNA-binding protein (TB-RBP) and its human homologue, Translin, ranging from mRNA transport and translational regulation to DNA rearrangement and repair. To gain insight into the likely functions of this 26 kDa protein, immunoprecipitation was used to identify proteins that interact with TB-RBP in mouse cytosolic extracts. Three proteins, the transitional endoplasmic reticulum ATPase, a cytoskeletal gamma actin, and Trax, were specifically immunoprecipitated with an affinity-purified antibody to recombinant mouse TB-RBP. In vitro binding assays with recombinant proteins and EM immunocytochemistry confirm that TB-RBP interacts with the TER ATPase in vitro and in vivo. Confocal microscopy has demonstrated that TB-RBP colocalizes with actin in the cytoplasm of male germ cells. The immunoprecipitation of Trax with TB-RBP confirms a published report demonstrating protein interactions between the two proteins in a yeast two-hybrid assay. These data support the hypothesis that TB-RBP serves as a link in attaching specific mRNAs to cytoskeletal structures and suggests an involvement for the ubiquitously expressed TER ATPase in intracellular and/or intercellular mRNA transport.

Testis-brain RNA-binding protein (Translin) is primarily expressed in neurons of the mouse brain

The subcellular location(s) of the DNA- and RNA-binding protein, Testis-Brain RNA-Binding Protein (TB-RBP)/Translin in mouse brain has been determined in paraffin sections by immunocytochemistry with an affinity purified antibody to mouse recombinant TB-RBP. Nuclear staining was frequently seen in neurons throughout the brain, but no TB-RBP/Translin was detected in many of the neurons in superficial layers of the cerebral cortex and in some cells of the cerebellum. Cytoplasmic staining extending into the dendrites was seen in large neurons such as pyramidal neurons in Layer 5 of the cortex and magnocellular neurons of the hypothalamus or the brainstem raphe.

Study on the direct electron transfer process of superoxide dismutase

The electron transfer process of biological important species, superoxide dismutase (SOD), was studied using cyclic voltammetric method at different conditions. The rate of electron transfer process of SOD at conventional bare gold electrode was very low. Different methods were used to enhance the rate of this process. Gold microdisk electrode and gold minigrid electrode were used to replace the used conventional size gold electrode and the electron transfer rate was enhanced obviously. Different promoters, such as bis(4-pyridyl)disulfide, histidine and arginine, were used to promote the electron transfer process also. Promising results were observed with the help of those promoters. The rate enhancement through the participation of amino acids might be more interesting for the exploration of the real process of SOD-related reaction inside the human body.

The DNA/RNA-binding protein, TB-RBP, moves from the nucleus to the cytoplasm and through intercellular bridges in male germ cells

The genetically haploid spermatids are functionally diploid as a result of the sharing of gene products through their intercellular bridges. This movement of molecules among haploid cells is crucial for the production of spermatozoa since numerous essential proteins are encoded on sex chromosomes. Testis-brain RNA-binding protein (TB-RBP) is a single-stranded DNA- and RNA-binding protein prominent in the nuclei and cytoplasm of specific stages of differentiating male germ cells. Here we present evidence that TB-RBP moves from the nucleus to the cytoplasm and through intercellular bridges of male germ cells. Based on its RNA-binding capabilities, we propose a role for TB-RBP in the distribution of equal amounts of mRNAs in haploid male germ cells.

Dimerization of the testis brain RNA-binding protein (translin) is mediated through its C-terminus and is required for DNA- and RNA-binding

Testis brain-RNA-binding protein (TB-RBP) is a single-stranded DNA- and RNA-binding protein that is involved in chromosomal translocations, mRNA transport and translational regulation. Here we show from in vitro and in vivo protein binding studies that TB-RBP dimers are the minimum structural unit needed for DNA- and RNA-binding. Truncation studies demonstrate that the C-terminus of 55 amino acids of TB-RBP is essential, but not sufficient for DNA- or RNA-binding, and deletion of the leucine zipper motif in the C-terminus abolishes DNA- and RNA-binding. Changing cysteine 225 in the C-terminus to alanine does not significantly reduce DNA- or RNA-binding, but reduces the stability of the dimer. We conclude that the leucine zipper motif is required to maintain two molecules of TB-RBP as a dimer which is stabilized by a disulfide bond involving cysteine 225.

The RNA- and DNA-binding protein TB-RBP is spatially and developmentally regulated during spermatogenesis

Testis brain RNA-binding protein (TB-RBP) suppresses translation in vitro and attaches mRNAs to microtubules by binding to conserved elements in the 3' untranslated regions (UTRs) of specific testis and brain mRNAs. Purification of TB-RBP from testicular and brain cytoplasmic extracts has revealed that mouse TB-RBP is 99% identical to the human protein translin, a recombination "hot spot" binding protein associated with chromosomal translocations. Using a cDNA encoding TB-RBP, the gene copy number and the developmental expression of TB-RBP have been analyzed by Southern blotting, Northern blotting, and in situ hybridization. In the mouse, TB-RBP is encoded by a single copy gene. In mouse testes, three TB-RBP mRNAs of about 1.2, 1.7, and 3.0 kb are developmentally regulated with high levels of expression in meiotic and postmeiotic germ cells. A fourth TB-RBP transcript of about 3.2 kb is seen in the brain. In situ hybridization confirms high levels of testicular TB-RBP mRNAs in meiotic and postmeiotic cells, with the highest levels of TB-RBP mRNAs in pachytene spermatocytes and round spermatids of the mouse and in round spermatids of the rat. RNase H digestion assays reveal that the three TB-RBP mRNAs of mouse testes result from processing differences in their 3' untranslated regions. These data demonstrate that multiple TB-RBP mRNAs are primarily expressed in meiotic and postmeiotic germ cells in the mammalian testis, and although the specific RNA-binding ability of TB-RBP appears limited to brain and testis, TB-RBP mRNAs are widely expressed.

The RNA-binding protein, TB-RBP, is the mouse homologue of translin, a recombination protein associated with chromosomal translocations

The mouse RNA-binding protein, TB-RBP, suppresses translation in vitro and attaches mRNAs to microtubules by binding to conserved elements in the 3' untranslated regions of specific mRNAs. We have now purified TB-RBP from testicular and brain cytoplasmic extracts and cloned its cDNA. We find that the mouse TB-RBP cDNAs contain an open reading frame of 228 amino acids with a leucine zipper domain within its C terminus, a transmembrane helix, and a group of putative phosphorylation sites. TB-RBP shows 99% identity to the human protein, translin, a recombination hotspot-binding protein associated with chromosomal translocations [Aoki, K., Suzuki, K., Sugano, T., Tasaka, T., Nakahara, K., Kuge, O., Omori, A. & Kasai, M. (1995) Nat. Genet. 10, 167-174]. As shown for translin, TB-RBP also binds to single-stranded DNAs containing a broad range of consensus sequences, many of which are similar to the Y and H RNA-binding sequences. Recombinant TB-RBP was synthesized and an antiserum was prepared against the recombinant protein. The identity between translin and TB-RBP was confirmed by demonstrating that immunoprecipitation of TB-RBP from testicular extracts abolished formation of the RNA-TB-RBP complex. Based upon its DNA binding to target sequences in clustered breakpoint regions, we propose that TB-RBP may be involved in DNA recombination or DNA repair in male germ cells.

Effect of the amino acid attached to Escherichia coli initiator tRNA on its affinity for the initiation factor IF2 and on the IF2 dependence of its binding to the ribosome

We show that the nature of the amino acid in the formylaminoacyl-tRNA influences initiation factor (IF) 2 dependence of its ribosome binding and that this IF2 dependence reflects the relative affinity of the formylaminoacyl-tRNA for the initiation factor IF2. We compared the template-dependent ribosome binding activities, in the presence of initiation factors, of wild type and anticodon sequence mutants of Escherichia coli initiator tRNAs that carry formylmethionine (fMet), formylglutamine (fGln), or formylvaline (fVal). The fGln-tRNA bound less well than fMet-tRNA whereas the fVal-tRNA bound as well as fMet-tRNA. The rate and extent of binding of fGln-tRNA to the ribosome was significantly increased by further addition of purified initiation factor IF2. In contrast, the binding of fVal-tRNA or fMet-tRNA was not affected much by the addition of IF2. Using gel mobility shift assay, we have measured the apparent Kd values of the IF2.formylaminoacyl-tRNA binary complexes. These are 1.8, 3.5, and 10.5 microM for fMet-tRNA, fVal-tRNA, and fGln-tRNA, respectively.

Selenocysteine synthesis in mammalia: an identity switch from tRNA(Ser) to tRNA(Sec)

The mechanism of selenocysteine insertion into proteins is distinct from all other amino acids in all lines of descent in that it needs specific protein cofactors and a structurally unique tRNA(Sec). It is first aminoacylated with serine and further recognized among all other serylated serine isoacceptors by a selenocysteine synthase and is converted to selenocysteyl-tRNA(Sec). We present here the complete set of identity elements for selenylation of mammalian seryl-tRNA(Sec) and show that the transplantation of these elements into normal serine tRNA allows its selenylation. Four particular structural motifs differentiate eukaryotic tRNA(Sec) from normal tRNA(Ser): the orientation of the extra arm, the short 4 bp T psi C-stem, the extra long 9 bp acceptor-stem and the elongated 6 bp dihydrouridine-stem. Only the last two are essential and only together sufficient for selenocysteine synthesis, whereby the additional base-pairs of the acceptor-stem may be replaced by non-paired nucleotides. Each exchange of the first three structural motifs mentioned above between tRNA(Ser) and tRNA(Sec) resulted in a significant loss of serylation, indicating that the overall composition of particular structure elements is necessary to maintain normal functions of tRNA(Sec). Since we find that all seryl-tRNAs which are selenylated are also substrates for serine phosphorylation we propose that phosphoseryl-tRNA(Sec) is a storage form of seryl-tRNA(Sec).

Ribosome-initiator tRNA complex as an intermediate in translation initiation in Escherichia coli revealed by use of mutant initiator tRNAs and specialized ribosomes

For functional studies of mutant Escherichia coli initiator tRNAs in vivo, we previously described a strategy based on the use of tRNA genes carrying an anticodon sequence change from CAU to CUA along with a mutant chloramphenicol acetyltransferase (CAT) gene carrying an initiation codon change from AUG to UAG. Surprisingly, under conditions where the mutant initiator tRNA is optimally active, the CAT gene with the UAG initiation codon produced more CAT protein (3- to 9-fold more depending on the conditions) than the wild-type CAT gene. Here we show that two new mutant CAT genes having GUC and AUC initiation codons also produce more of the CAT protein in the presence of the corresponding mutant initiator tRNAs. These results are most easily understood if assembly of the 30S ribosome-initiator tRNA-mRNA initiation complex in vivo proceeds with the 30S ribosome binding first to the initiator tRNA and then to the mRNA. In cells overproducing the mutant initiator tRNAs, most ribosomes would carry the mutant initiator tRNA and these ribosomes would select the mutant CAT mRNA over the other mRNAs.

Inactivation and conformation changes of the glycated and non-glycated D-glyceraldehyde-3-phosphate dehydrogenase during guanidine-HCl denaturation

The glycated D-glyceraldehyde-3-phosphate dehydrogenases have been isolated from rabbit muscle and erythrocytes (He et al. (1995) Biochem. J. 309, 133-139). The circular dichroism spectrum in the near-ultraviolet of gGAPDH was different from that of GAPDH. Changes in intrinsic protein fluorescence and in the 410 nm fluorescence of the NAD derivatives introduced at the active sites of both the glycated and non-glycated GAPDH from rabbit were compared on inactivation during denaturation in GuHCl. Complete inactivation for the non-glycated enzyme occurred in 0.5 M GuHCl solution, however, that for the glycated enzyme occurred in the 0.35 M solution. The kinetic inactivation of gGAPDH was a biphasic process (the fast and slow phases). The fast phase for gGAPDH was faster than that of GAPDH. The kinetic exposure of the fluorescent NAD derivatives at the active sites of both enzymes was also biphasic with fast phase rates which approach those of the inactivation. It appears that glycation of the enzyme may disturb the spatial geometry of the functional groups responsible for the catalytic mechanism and affect the activity.

Escherichia coli initiator tRNA: structure-function relationships and interactions with the translational machinery

We showed previously that the sequence and (or) structural elements important for specifying the many distinctive properties of Escherichia coli initiator tRNA are clustered in the acceptor stem and in the anticodon stem and loop. This paper briefly describes this and reviews the results of some recently published studies on the mutant initiator tRNAs generated during this work. First, we have studied the effect of overproduction of methionyl-tRNA transformylase (MTF) and initiation factors IF2 and IF3 on activity of mutant initiator tRNAs that are defective at specific steps in the initiation pathway. Overproduction of MTF rescued specifically the activity of mutant tRNAs defective in formylation but not mutants defective in binding to the P site. Overproduction of IF2 increased the activity of all mutant tRNAs having the CUA anticodon but not of mutant tRNA having the GAC anticodon. Overproduction of IF3 had no effect on the activity of any of the mutant tRNAs tested. Second, for functional studies of mutant initiator tRNA in vivo, we used a CAU --> CUA anticodon sequence mutant that can initiate protein synthesis from UAG instead of AUG. In contrast with the wild-type initiator tRNA, the mutant initiator tRNA has a 2-methylthio-N6-isopentenyl adenosine (ms2i6A) base modification next to the anticodon. Interestingly, this base modification is now important for activity of the mutant tRNA in initiation. In a miaA strain of E. coli deficient in biosynthesis of ms2i6A, the mutant initiator tRNA is much less active in initiation. The defect is specifically in binding to the ribosomal P site.

Eukaryotic selenocysteine inserting tRNA species support selenoprotein synthesis in Escherichia coli

Although the tRNA species directing selenocysteine insertion in prokaryotes differ greatly in their primary structure from that of their eukaryotic homologues they share very similar three-dimensional structures. To analyse whether this conservation of the overall shape of the molecules reflects a conservation of their functional interactions it was tested whether the selenocysteine inserting tRNA species from Homo sapiens supports selenoprotein synthesis in E. coli. It was found that the expression of the human tRNA(Sec) gene in E.coli can complement a lesion in the tRNA(Sec) gene of this organism. Transcripts of the Homo sapiens and Xenopus laevis tRNA(Sec) genes synthesised in vitro were amino-acylated by the E.coli seryl-tRNA ligase although at a very low rate and the resulting seryl-tRNA(Sec) was bound to and converted into selenocysteyl-tRNA(Sec) by the selenocysteine synthase of this organism. Selenocysteyl-tRNA(Sec) from both eukaryotes was able to form a complex with translation factor SELB from E.coli. Although the mechanism of selenocysteine incorporation into seleno-proteins appears to be rather different in E.coli and in vertebrates, we observe here a surprising conservation of functions over an enormous evolutionary distance.

Sexing bovine embryos using PCR amplification of bovine SRY sequence

This study analyses the bovine SRY DNA sequence by direct sequencing procedure, followed by the designation of the PCR primers specific for bovine SRY. Using PCR amplification of bovine SRY gene, the embryo sex was determined. The results of the embryo sex identification were confirmed after the embryo transfer and pregnancies.

The length and the secondary structure of the D-stem of human selenocysteine tRNA are the major identity determinants for serine phosphorylation

Selenocysteine tRNA [tRNA(Ser)Sec] has been shown to be serylated by tRNA(Ser) synthetase. The serine moiety of seryl-tRNA(Ser)Sec in vertebrates is further phosphorylated by a kinase, in addition to being converted into selenocysteine. Using site-directed mutagenesis we have introduced a number of mutations into T7 RNA polymerase transcripts of human tRNA(Ser)Sec. Our results show that most of the unique structural features of tRNA(Ser)(Sec), like the 5'-triphosphate, the 9 bp long acceptor stem and the anticodon, are not identity elements for phosphorylation of human seryl-tRNA(Ser)Sec. However, the length and secondary structure of the D-stem (6 bp in contrast with 4 bp in the canonical serine tRNA) of human tRNA(Ser)Sec, but not its sequence, are the major identity determinants which discriminate this tRNA from common tRNA(Ser) and identify it as the substrate for phosphorylation by seryl-tRNA(Ser)Sec kinase. This notion is confirmed by the fact that normal seryl-tRNA(Ser), which is not a substrate for serine phosphorylation, becomes a substrate if two additional base pairs are introduced into its D-stem.