[Mental health problems among female staff in a provincial maternal and child health hospital: an investigation of 647 individuals].

Objective: To investigate the current status of depression and anxiety among female staff in a maternal and child health hospital, and to provide a basis for developing related prevention and intervention measures and promoting the mental health of female staff. Methods: The female staff from a provincial maternal and child health hospital completed a psycho-health questionnaire survey on Internet from June to October, 2016. The questionnaires used in the survey consisted of Patient Health Questionnaire (PHQ-9) , Generalized Anxiety Disorder Scale (GAD-7) , and Symptom Checklist-90 (SCL-90) . The distribution features of mental health problems such as depression and anxiety were analyzed according to the results: of the questionnaire survey. Results Of all female staff surveyed, 42.04% showed depression symptoms, 28.90% showed anxiety symptoms, and 26.12% showed comorbid symptoms of depression and anxiety. Moderate or severe depression (anxiety) was mainly distributed among the female staff with comorbid symptoms (90.63% and 97.01%, respectively) . There were significant differences in the distribution of moderate or severe anxiety symptoms between the medical staff and nursing staff (χ(2)= 5.81, P=0.05) and between those with intermediate and junior professional titles (χ(2)=7.99, P=0.018) . As for SCL-90 results, the total score, total average score, and scores on factors of somatization, compulsion, interpersonal sensitivity, depression, and anxiety in the female staff with comorbid symptoms, moderate or severe depression, and moderate or severe anxiety were significantly higher than the national norm (P<0.01) , while the scores on paranoid and psychotic factors were significantly lower than the national norm (P<0.01) . The numbers of cases of positive factors were significantly higher in the female staff with comorbid symptoms than in the female staff with a single symptom and asymptomatic female staff (both P<0.01) , and positive cases were mainly distributed in depression, interpersonal sensitivity, compulsion, anxiety, and somatic factors. Conclusion: The prevalence of depression and anxiety is high among female staff in the maternal and child health hospital, mainly characterized by comorbid symptoms of moderate or severe depression and anxiety. Comorbidity is accompanied by mental health problems such as interpersonal sensitivity, obsessive compulsion, and physical discomfort. Corresponding measures are needed for the prevention and intervention of mental health problems among female staff in the maternal and child health hospital.

[Current status of reproductive health and its occupational influencing factors among female medical staff in a provincial maternal and child health hospital].

Objective: To investigate the current status of reproductive health among the female medical staff in a provincial maternal and child health hospital and analyze the occupational influencing factors for reproductive health, particularly the effects of high-intensity work, work shift, chemical poisons, and physical and biological factors on reproductive health, and to provide a scientific basis for developing related intervention measures and promoting the reproductive health of professional females. Methods: A reproductive health questionnaire was designed in terms of age, type of work, professional title, education level, working hours, working strength, and the reproductive health of female staff to analyze the current status of reproductive health, working strength, and occupational hazardous factors. The female medical staff in the provincial maternal and child health hospital completed the questionnaire on the internal network of the hospital voluntarily. Results: Of all respondents, 19.46% had a history of miscarriage, 5.90% visited the hospital due to infertility, 21.31% had irregular menstruation within the last 3 months, and 30.57% had reproductive system disease; 72.28% of the investigated medical staff often worked at night, 47.25% often worked overtime (more than 3 days a week) , and 22.27% worked over 8 hours daily. The respondents who often worked overtime had a significantly higher prevalence of reproductive system disease than those who did not often work overtime (χ(2)= 58.65, P<0.01) . The respondents who often worked at night had a significantly higher rate of miscarriage than those who did not work at night (χ(2)=41.57, P<0.01) . In all respondents, 87.08% were often exposed to chemical injuries such as disinfectants, and 78.15% had contact with noise, radiation, and other physical injuries; the medical staff exposed to chemical and physical injuries had a significantly higher proportion of individuals with a history of miscarriage than the unexposed staff (χ(2)=10.04, P<0.01; χ(2)=13.30, P<0.01) . Conclusion: Much attention should be paid to the reproductive health of female medical staff in the provincial maternal and child health hospital, who have high working strength. The occupational hazard factors can be avoided by reasonably arranging the work schedule and creating a supportive environment to improve the reproductive health of female medical staff.

Swine leukocyte antigen class II genes (SLA-DRA, SLA-DRB1, SLA-DQA, SLA-DQB1) polymorphism and genotyping in Guizhou minipigs.

The swine leukocyte antigen (SLA) complex harbors highly polymorphic gene clusters encoding glycoproteins that are involved in responses to vaccines, infectious disease, and production performance. Pigs with well-defined SLA class II genes are useful for the study of disease, immunology, and vaccines. In this study, we analyzed four SLA class II genes (SLA-DRA, SLA-DRB1, SLA-DQA, SLA-DQB1) in 22 founder Guizhou minipigs using a sequence-based typing method. Twelve alleles were detected, compared with the SLA class II allele sequences in the GenBank, and one of twelve alleles was found to be novel in Guizhou minipigs. There are four SLA II haplotypes, and one of them has been previously reported in Meishan pigs. Furthermore, based on sequence information of these alleles, we developed a simple SLA typing method implemented to SLA-typing for unknown offspring of Guizhou minipigs, relying on designed twelve sequence specific primers that could discriminate between each other. According to the combination of sequence-based typing and PCR-SSP, we were able to rapidly check SLA typing of Guizhou breeding stock and identified four SLA haplotypes in the herd. Therefore, SLA-defined Guizhou minipigs will be useful as animal models for xenotransplantation and immunological research.

[Epidemiological characteristics and drug resistance of diarrheagenic Escherichia coli infection in diarrhea patients in Shanghai, 2016-2022].

Objective: To understand the infection status, epidemiological characteristics and drug resistance of Diarrheagenic Escherichia coli (DEC) in Shanghai and provide evidence for the disease surveillance. Methods: The epidemiological data of diarrhea cases in Shanghai from 2016 to 2022 were collected from Shanghai Diarrhea Comprehensive Surveillance System, and stool samples were collected from the cases for DEC detection. The drug resistance data was obtained from Chinese Pathogen Identification Network. Statistical analysis was conducted by using χ2 and fisher test. Results: In 24 883 diarrhea cases detected during 2016-2022, the DEC positive rate was 9.13% (2 271/24 883), the single DEC positive rate was 8.83% (2 197/24 883) and the mixed DEC positive rate was 0.30% (74/24 883). The main type of DEC was Enterotoxigenic Escherichia coli (ETEC) [4.33% (1 077/24 883)]. The DEC positive rate was highest in people aged ≤5 years 18.48% (22/119). The annual peak of DEC positive rate was observed during July - September [5.91% (1 470/24 883)]. The DEC positive rate were 9.47% (554/5 847) and 9.02% (1 717/19 036) in urban area and in suburbs, respectively, Enteroaggregative Escherichia coli (EAEC) [3.98% (233/5 847)] and ETEC [4.56% (868/19 036)] were mainly detected. From 2016 to 2019, the DEC positive rate was 9.42% (1 821/19 330), while it was 8.10% (450/5 553) from 2020 to 2022, the main DEC types were ETEC (4.87%, 941/19 330) and EAEC (4.70%, 261/5 553). The multi-drug resistance rate was 40.21% (618/1 537). The top three antibiotics with high drug resistance rates were ampicillin [64.74% (995/1 537)], nalidixic acid [58.49% (899/1 537)] and tetracycline [45.09% (693/1 537)]. Conclusions: Compared with 2016- 2019, a decrease in DEC detection rate was observed during 2020-2022, and the main type of DEC detected shifted from ETEC to EAEC. The prevalence of multi-drug resistance was severe. Therefore, it is necessary to further strengthen the surveillance for DEC drug resistance and standardize the use of clinical antibiotics.

Mutations in the gene encoding gap junction protein beta-3 associated with autosomal dominant hearing impairment.

Hearing impairment is the most commonly occurring condition that affects the ability of humans to communicate. More than 50% of the cases of profound early-onset deafness are caused by genetic factors. Over 40 loci for non-syndromic deafness have been genetically mapped, and mutations in several genes have been shown to cause hearing loss. Mutations in the gene encoding connexin 26 (GJB2) cause both autosomal recessive and dominant forms of hearing impairment. To study the possible involvement of other members of the connexin family in hereditary hearing impairment, we cloned the gene (GJB3) encoding human gap junction protein beta-3 using homologous EST searching and nested PCR. GJB3 was mapped to human chromosome 1p33-p35. Mutation analysis revealed that a missense mutation and a nonsense mutation of GJB3 were associated with high-frequency hearing loss in two families. Moreover, expression of Gjb3 was identified in rat inner ear tissue by RT-PCR. These findings suggest that mutations in GJB3 may be responsible for bilateral high-frequency hearing impairment.

Significant associations of polymorphisms in the prolactin gene with growth traits in Asian seabass (Lates calcarifer).

Prolactin (encoded by PRL) is a multifunctional hormone involved in osmoregulation, reproduction, growth, development, immunomodulation, endocrine and metabolic regulation. We cloned the full-length cDNA of Asian seabass PRL, searched for polymorphism in the DNA sequence, and conducted association analyses. Twelve SNPs and one 4-bp deletion were identified in PRL. The SNP c.264+127C>G was used for linkage mapping, and this gene was mapped to linkage group 11. The c.264+980_983delTTGT, c.264+127C>G, c.264+138T>G, c.264+269T>C and c.330C>G polymorphisms were genotyped in 521 individuals with growth trait records. Association analyses between single markers and growth traits revealed that the c.264+269T>C SNP was significantly associated with body weight (BW), total length (TL), standard length (SL) and Fulton's condition factor (KTL and KSL), while the other four were not. Analysis of haplotypes showed that there were 10 haplotypes and 22 haplotype combinations in the population. The differences of BW, TL, KTL and KSL among different haplotype combinations were significant.

Interleukin-6 is essential for Staphylococcal exotoxin B-induced T regulatory cell insufficiency in nasal polyps.

BACKGROUND: The pathogenesis of nasal polyps is still unclear. There is increasing evidence indicating that Staphylococcal aureus (S. aureus) is associated with the formation of nasal polyps, but the mechanism has not been well documented to date. METHODS: We stimulated cultured nasal polyps and turbinate tissues with Staphylococcal exotoxin B (SEB), detected the expression of pro-inflammatory cytokines (IL-2, IL-6, and IL-8) and T cell cytokines (IFN-gamma, IL-4, IL-5, IL-10, and IL-17) in the supernatants, and evaluated mRNA expression (T-bet, GATA-3, Foxp3, and RORgammat) and frequencies of CD4+CD25+ T regulatory cells (Tregs) in nasal tissues. We also evaluated the effects of blocking IL-6 with monoclonal antibodies to T cell profiles in cultured nasal tissues stimulated by SEB. RESULTS: Levels of IL-6, IFN-gamma and IL-4 increased significantly in SEB-stimulated nasal polyps. Meanwhile, mRNA expressions of T-bet and GATA-3 were significantly up-regulated, while Foxp3 was inhibited and the frequencies of CD4+CD25+ Tregs were decreased after SEB stimulation. After blocking IL-6, the levels of IL-10 and Foxp3 mRNA, as well as the frequencies of CD4+CD25+ Tregs, were significantly increased, while IFN-gamma and IL-4 production and the mRNA expression of T-bet and GATA-3 were significantly inhibited. CONCLUSIONS: SEB is able to modulate pro-inflammatory factors, T-helper type 1/Th2 profiles and suppress Treg activity in cultured nasal polyps, which were rescued by blocking IL-6 activity. Therefore, IL-6 is essential for SEB-induced Treg insufficiency in nasal polyps.

Mutation L437P in the 2B domain of keratin 1 causes diffuse palmoplantar keratoderma in a Chinese pedigree.

Diffuse palmoplantar keratoderma (DPPK) is an autosomal dominant genodermatosis characterized by uniform hyperkeratosis of the palm and sole epidermis. This disorder can be caused by mutations in the genes keratin 1, keratin 9, keratin 16, desmoglein 1 and plakoglobin. Here we present a DPPK Chinese pedigree and identify the aetiology as a novel missense mutation, L437P, located in a highly conserved helix motif in domain 2B of KRT1. Functional analysis shows that overexpression of the L437P mutant in cultured cells leads to abnormal intermediate filament networks and filament aggregation. This gain-of-function mutation highlights the role of domain 2B in mediating filament assembly.

[Epidemiological characteristics of HIV infected pregnant women and exposed infants in Guangdong province, 2014-2017].

Objective: To analyze the epidemiological characteristics of HIV-infected pregnant women and exposed infant in Guangdong province and identify the factors associated with infant HIV infection through mother-to-child transmission. Methods: National Information System for Prevention of mother-to-child HIV Transmission and Early Infant Diagnosis Information Management Platform were used to collect the individual information about HIV-infected pregnant women and exposed infants who were delivered in Guangdong from January 1, 2014 to December 31 in 2017. The differences in pregnant women's demographic data, history of pregnancy and childbirth, the utilization of mother-to-child transmission prevention services and early infant diagnosis between the infected HIV exposed infants and uninfected HIV exposed infants were compared, and univariate and multivariate logistic regression analyses were conducted to identify the factors associated with mother-to-child HIV transmission. Results: Among 349 HIV infected pregnant women, the proportions of the pregnant women whose HIV infection status were confirmed before pregnancy, during pregnancy and at or after childbirth were 30.4% (106/349), 49.6% (173/349) and 20.0% (70/349) respectively. The proportions of those with sexual partners whose HIV infection status were unknown and those receiving no antiviral treatment were 39.5% (138/349) and 13.2% (46/349) respectively. Among the HIV exposed infants, the mother-to-child transmission rate was 4.2%(15/353), the HIV exposed infants had the first or second early diagnosis tests within 44 (P(25)-P(75): 42-50) days and 96 (P(25)-P(75): 92-106) days after birth, respectively. Univariate logistic regression analysis indicated that the risk for mother-to-child HIV transmission increased in those whose HIV infection status were confirmed at or after childbirth compared with before pregnancy (OR=5.72, 95%CI: 1.52-21.61) and in the group that antiviral treatment was given to either mothers or infants compared with the group that antiviral treatment was given to both mothers and infants (OR=33.56, 95%CI: 9.04-124.55), while there was lower mother-to-child HIV transmission risk in artificial feeding group compared with breast feeding group (OR=0.07, 95%CI: 0.01-0.76). Conclusion: The risk of mother-to-child HIV transmission in Guangdong can be effectively reduced by the measures of early diagnosis, antiviral treatment and artificial feeding as well as the improvement of mother-to-child transmission prevention service.

Foxp3+ T regulatory cells (Tregs) are increased in nasal polyps (NP) after treatment with intranasal steroid.

The pathogenesis of chronic rhinosinusitis (CRS) with nasal polyps(NP) is still poorly understood. To evaluate the role of Foxp3+ T regulatory cells (Tregs) in the pathogenesis and management of NP, we investigated the location and expression of Foxp3 in NP before and after treatment with intranasal steroid. NP specimens were obtained from 14 patients with NP before and after intranasal administration of mometasone (50 microg/day for 4 weeks). Foxp3 was detected by double immunofluorescence stain, quantitative reverse transcriptase polymerase chain reaction (RT-PCR), flow cytometry and western blot. The concentration of interleukin(IL)-10 in supernatants of homogenized tissue was measured by enzyme-linked immunosorbent assay (ELISA). We found that Foxp3 and IL-10 were downregulated in NP compared to the control mucosa (P<0.05). Foxp3 and IL-10 expression were increased significantly after intranasal steroid treatment (P<0.05). And Foxp3 was tightly correlated with IL-10 in NP (P<0.05) after treatment. These data suggest that Foxp3 is downregulated in NP and intranasal steroid attenuates the chronic inflammatory response by enhancing the expression and function of Foxp3 in NP.

Characterization of reflection intermittency in a composite granular chain.

The physical factors controlling the power-law behavior of impact energy in a composite granular chain remain elusive. Based on event-driven simulations and the on-off intermittency of wave reflections, we obtain the probability distribution functions of the waiting time tau and the energy leakage DeltaE . They exhibit lognormal distributions, which together with the relationship between DeltaE and tau allow one to explain directly the power-law behavior of the confined energy. This work may be extended to higher dimensions and help us understand the complex dynamics in granular materials.

LncRNA PCAT-1 regulates the proliferation, metastasis and invasion of cervical cancer cells.

OBJECTIVE: To investigate the effects of long non-coding RNA (lncRNA) PCAT-1 on the proliferation, metastasis, and invasion of cervical cancer cells. MATERIALS AND METHODS: LncRNA PCAT-1 small interfering RNA (siRNA) and negative siRNA were transfected into cervical cancer cell lines and the expression of lncRNA PCAT-1 in cells was confirmed by Real-time quantitative polymerase chain reaction (qPCR). Cell counting kit-8 (CCK-8) and colony formation assay were applied to detect the effect of lncRNA PCAT-1 on cell proliferation. The wound-healing assay was applied to test the effect of lncRNA PCAT-1 on cell metastasis. Matrigel cell invasion assay was performed to detect the impact of lncRNA PCAT-1 expression on invasion. RESULTS: After transfected with the long non-coding PCAT-1 siRNA into cervical cancer cell lines for 48 h, the lncRNA PCAT-1 cells were significantly down-regulated. The results of CCK-8, clonogenic and wound-healing assay showed that the decreased expression of lncRNA PCAT-1 attenuated the proliferation and metastasis of cells. The results of matrigel cell invasion assay manifested that the decreased expression of lncRNA PCAT-1 could reduce the invasion ability. The up-regulation of lncRNA PCAT-1 was associated with poor prognosis of patients with cervical cancer. CONCLUSIONS: LncRNA PCAT-1 siRNA transfected into cervical cancer cell lines can effectively lower the expression of lncRNA PCAT-1, while lncRNA PCAT-1 expression can inhibit the proliferation, metastasis and invasion abilities of cervical cancer cells.

Crossover in the power-law behavior of confined energy in a composite granular chain.

We present a numerical study of the impact energy decay in a composite granular chain containing two heavy and one light sections. We observe a marked crossover in the power-law behavior of the impact-energy decay. The average reflection frequency first increases with a decreasing acceleration, and arrives at its maximum at "crossing" time then decays almost exponentially. The analysis demonstrates that this phenomenon is related to the structural transition from compression to dilation state in both heavy-particle sections. The further calculations suggest the dependence relation of the power-law exponent (gammacb) in compression state on the mass ratio (m2/m1) and the Hertz law exponent (n) of the composite granular chain gammacb approximately (m2/m1)1/(n+1).

Risk factors associated with mortality from vascular thromboembolic events in patients diagnosed with non-small cell lung cancer: a population-based analysis.

BACKGROUND: Lung cancer patients are at increased risk for vascular events possibly due to cancer induced hypercoagulation. AIM: The purpose of this study was to evaluate risk factors associated with the mortality from vascular thromboembolic events in patients diagnosed with non-small cell lung cancer (NSCLC). DESIGN: Retrospective population-based analysis. METHODS: We used Surveillance, Epidemiology and End Results Program for 2004-13 and evaluated 199 337 patients with NSCLC. Univariate and multivariate subdistribution hazard regression models were used to identify potential risk factors for mortality from vascular thromboembolic events. Stratification analysis against clinical stage was performed to determine if the severity of the disease influenced the identified associations. RESULTS: Multivariate Cox regression analysis demonstrated that increased risk of mortality due to vascular thromboembolic events was associated with age, black race, non-adenocarcinoma histology, surgical treatment alone (all, P < 0.001) and north central region of SEER registry (P = 0.003). Female gender (P < 0.001), Asian or Pacific Islander race (P = 0.001), multiple co-existing primary cancers and late cancer stages (both, P < 0.001) were associated with significantly lower risk of mortality due to vascular thromboembolic events. The significant predictors of mortality from the vascular thromboembolic event were dependent on the stages of the disease. CONCLUSIONS: Risk factors associated with mortality from the vascular thromboembolic events in NSCLC patients identified in this study can promote awareness and may help to identify groups of patients that can benefit from anti-thrombotic prophylaxis measures.

The effects of MCA-MAO on cAMP pathway in rats with cerebral hemorrhage.

OBJECTIVE: To explore the effects of MCA-MAO on the cAMP pathway in rats with cerebral hemorrhage. MATERIALS AND METHODS: Forty SD male rats were randomly divided into four groups: the sham operation group (n=10), the model group (n=10), the negative control group (n=10) and the experimental group (n=10). To prepare rat models for cerebral hemorrhage, autogenous femoral arterial blood was injected into the caudate nucleus. In the case of rats in sham operation group, normal saline was injected into the caudate nucleus. Rats in the negative control group received a proper amount of saline via an injection into the abdominal cavity. Rats in the experimental group were injected with 500 µL/kg MCA-MAO into the abdominal cavity. Five rats from each group were executed after 1 to 3 days, the water contents of gray and white matters were detected using far infrared moisture analyzer, the MAO activity was measured by the histochemical method. The cAMP level was measured by radio-immunity method and the protein kinase A (PKA) level was measured by Western blot. cAMP response element binding (CREB) mRNA expression level was detected by RT-PCR. RESULTS: Water content, MAO activity, cAMP, PKA, and CREB mRNA expression levels in the model, and the negative control groups were significantly higher than those of the sham operation and the experimental groups, the differences were statistically significant (p<0.05). CONCLUSIONS: MAO may mediate the pathophysiological process of hemorrhage via cAMP signaling pathway.

Expressions of serum inflammatory cytokines and their relationship with cerebral edema in patients with acute basal ganglia hemorrhage.

OBJECTIVE: The aim of the present study is to investigate expressions of inflammatory cytokines and their relationship with cerebral edema in the patients with acute basal ganglia hemorrhage. PATIENTS AND METHODS: Between January 2015 and March 2016, 94 patients with acute basal ganglia hemorrhage admitted to our institution were included in the present study. Serum levels of interleukin (IL)-4, IL-6, IL-8 and IL-10 were measured using enzyme-linked immunosorbent assay (ELISA), and conditions of cerebral edema were evaluated using head CT upon admission, 1d after admission and 3d after admission, respectively. RESULTS: Serum levels of IL-4, IL-6 and IL-8 peaked 1d after admission and decreased 3d after admission with statistical significance (p <0.05); the IL-10 level was continuously increased after admission and peaked 3 days after admission with statistical significance (p<0.05). Cerebral edema was not observed in any of these patients upon admission, while occurred with a maximal edema volume 1 day after admission and the volume decreased 3 days after admission with statistical significance (p <0.05). Correlation analysis showed that levels of IL-4, IL-6 and IL-8 were positively correlated with severity of cerebral edema (r=0.324, 0286, 0.305, p <0.05 respectively), whereas IL-10 level was negatively correlated with severity of cerebral edema (r=-0.336, p <0.05). CONCLUSIONS: Serum levels of IL-4, IL-6 and IL-10 are positively correlated while the IL-10 level is negatively correlated with the severity of the cerebral edema in patients with acute basal ganglia hemorrhage.

Relationship between levels of inflammatory cytokines in the peripheral blood and the severity of depression and anxiety in patients with Parkinson's disease.

OBJECTIVE: The present study aims to investigate the relationship between expression of inflammatory cytokines in the peripheral blood and the severity of depression and anxiety in patients with Parkinson's disease (PD). PATIENTS AND METHODS: Between January 2012 and December 2015, 62 PD patients admitted to our institution were included in the PD group, and 62 healthy subjects seeking health check-up at our institution during the same period of time were enrolled in the control group. Levels of inflammatory cytokines, including IL-1b, IL-6, interferon-g (INF-g), hypersensitive C-reactive protein (hsCRP) and soluble IL-2 receptor (sIL-2R), were measured by using Enzyme-linked immunosorbent assay (ELISA). Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) were used to assess the severity of depression and anxiety, respectively. RESULTS: A total of 124 subjects were included into PD group and control group, 62 for each. No significant differences were observed in the gender, age, body mass index (BMI), smoking history and alcohol history between two groups (p > 0.05). Levels of IL-1b, IL-6, TNF-a, hsCRP and sIL-2R were significantly higher in patients of PD group than those in the control group (p < 0.05). HAMD and HAMA scores in PD group were significantly higher than those in the control group [(22.74 ± 6.34), (20.90 ± 5.86) vs. (2.17±3.46), (3.79 ± 3.55), p < 0.05]. HAMD and HAMA scores were positively correlated with the levels of TNF-a, hsCRP and sIL-2R in the peripheral blood of PD patients (p < 0.05). CONCLUSIONS: Expression of inflammatory cytokines are elevated in the peripheral blood of PD patients, and the severity of depression and anxiety is correlated with levels of TNF-a, hsCRP and sIL-2R in the peripheral blood of these patients.

Regulation of H+ Extrusion and Cytoplasmic pH in Maize Root Tips Acclimated to a Low-Oxygen Environment.

We tested the hypothesis that H+ extrusion contributes to cytoplasmic pH regulation and tolerance of anoxia in maize (Zea mays) root tips. We studied root tips of whole seedlings that were acclimated to a low-oxygen environment by pretreatment in 3% (v/v) O2. Acclimated root tips characteristically regulate cytoplasmic pH near neutrality and survive prolonged anoxia, whereas nonacclimated tips undergo severe cytoplasmic acidosis and die much more quickly. We show that the plasma membrane H+-ATPase can operate under anoxia and that net H+ extrusion increases when cytoplasmic pH falls. However, at an external pH near 6.0, H+ extrusion contributes little to cytoplasmic pH regulation. At more acidic external pH values, net H+ flux into root tips increases dramatically, leading to a decrease in cytoplasmic pH and reduced tolerance of anoxia. We present evidence that, under these conditions, H+ pumps are activated to partly offset acidosis due to H+ influx and, thereby, contribute to cytoplasmic pH regulation and tolerance of anoxia. The regulation of H+ extrusion under anoxia is discussed with respect to the acclimation response and mechanisms of intracellular pH regulation in aerobic plant cells.

Improved Cytoplasmic pH Regulation, Increased Lactate Efflux, and Reduced Cytoplasmic Lactate Levels Are Biochemical Traits Expressed in Root Tips of Whole Maize Seedlings Acclimated to a Low-Oxygen Environment.

We tested the hypothesis (J.-H. Xia and P.H. Saglio [1992] Plant Physiol 100: 40-46) that the enhanced ability of maize (Zea mays) root tips to survive anoxia, elicited by a 4-h exposure to 3% O2 ("acclimation"), is due to less cytoplasmic acidosis early in anoxia. Cytoplasmic pH and fermentation reactions were monitored in excised and intact (attached) maize root tips by simultaneous in vivo 13C- and 31P-NMR spectroscopy. We demonstrate that both excised and intact acclimated root tips have significantly higher cytoplasmic pH values under anoxia. This reduction in cytoplasmic acidosis is greater in intact root tips. Remarkably, cytoplasmic pH does not change when root tips are transferred from 3% O2 to anoxia. The earlier observation of considerable lactate efflux and lowered intracellular lactate in excised, acclimated root tips (ibid.) was extended to intact seedlings. The predominant fermentation end product retained in the cells of acclimated root tips is alanine. We discuss the relationship between cytoplasmic pH and levels of intracellular lactate and alanine in sugar-replete roots, and the role of cytoplasmic pH in determining survival under anoxia.