[Comparative analysis on prevalence of tobacco and e-cigarettes uses in junior middle school students in Shanghai, 2013 and 2019].

Objective: To examine the prevalence and trend of tobacco and e-cigarettes uses and identify the influencing factors for smoking behavior in junior middle school students in Shanghai, and provide data support and scientific basis for the development of tobacco control intervention strategy in adolescents. Methods: Multi-stage stratified random sampling method was used to select junior middle school students in 8 districts and 10 districts in Shanghai in 2013 and in 2019 respectively. Information about tobacco and e-cigarettes uses in the students were collected by using self-administrated questionnaire. The prevalence of tobacco and e-cigarettes uses were calculated, the difference between two years was compared with χ2 test. The influencing factors were identified by multivariate logistic regression analysis. Results: In 2019, the current smoking rate was 0.6% in junior middle school students in Shanghai, and the smoking attempt rate was 2.9%, both were lower than the levels in 2013 (0.7% and 6.9%). The current use rate of e-cigarettes was 0.6% in 2019,with no significant change compared with 2013 (0.6%). The proportion of the students who had heard of e-cigarettes in 2019 (78.4%) was higher than that in 2013 (47.2%). In 2019, the second-hand smoke (SHS) exposure rate at home, in both indoor and outdoor public places and on public transportations was 72.5%, which was slightly lower than the level in 2013 (73.0%), the differences were all significant (P<0.05). In 2019, the students seeing close friend smoking (OR=27.381, 95%CI: 12.037-62.287), seeing someone smoking in school (OR=2.477, 95%CI: 1.155-5.312), believing that SHS may not be harmful (OR=8.471, 95%CI: 1.464-49.005) had higher possibility of smoking. Being aged ≥15 years (compared with being aged ≤12 years, OR=8.688, 95%CI: 1.922-39.266), exposure to SHS in outdoor public place (OR=8.608, 95%CI: 1.048-70.692), close friend smoking (OR=8.115, 95%CI: 1.754-37.545) were positively associated with e-cigarettes use, and believing that smoking results in uncomfortable social contact [compared with believing that smoking results in comfortable social contact (OR=0.105,95%CI: 0.018-0.615)] were negatively associated with e-cigarettes use, the difference was significant (P<0.05). Conclusion: The prevalence of tobacco and e-cigarette uses in junior middle school students in Shanghai remained at a low level in recent years. The SHS exposure rate in junior middle school students is high. Smoking behavior of junior middle school students is closely related to personal attitude and awareness of tobacco, exposure to SHS, peer smoking and the situation of tobacco control in schools. Prevention and intervention should be carried out from multi-dimensions to effectively protect teenagers from tobacco hazards.

Urinary biomarkers of early renal injury in antiretroviral-naïve HIV-positive persons in Shanghai, China: comparison with the general population.

OBJECTIVES: People living with HIV (PLWH) have a high risk of kidney injury. Measurement of serum creatinine, along with proteinuria, is not sensitive to detect early kidney injury. Here, we investigated novel urinary biomarkers of early renal injury in PLWH. METHODS: We performed a cross-sectional study of 166 antiretroviral-naïve PLWH and 99 HIV-negative persons who all had an estimated glomerular filtration rate > 90 mL/min/1.73 m2 . We compared the levels of seven urinary biomarkers between the two groups using the propensity score matching (PSM) approach and explored the risk factors associated with elevated urinary biomarkers in PLWH. RESULTS: Eighty-three pairs were successfully matched based on PSM. Compared with the HIV-negative group, the HIV-positive group had higher ratios of N-acetyl-ß-D-glucosaminidase (NAG) to urine creatinine (UCr), alpha1-microglobulin (α1-M) to UCr, kidney injury marker-1 (KIM-1) to UCr, neutrophil gelatinase-associated lipocalin to UCr, and epidermal growth factor to UCr, whereas the Tamm-Horsfall protein to UCr ratio and the abnormal albumin to UCr ratio were not significantly different. Positive correlations were observed between HIV RNA level and NAG: UCr (rs  = 0.32; P < 0.001) and α1-M:UCr (rs  = 0.24; P = 0.002) ratios, and negative correlations were observed between CD4 cell count and NAG:UCr (rs  = -0.34; P < 0.001), KIM-1:UCr (rs  = -0.16; P = 0.042) and α1-M:UCr (rs  = -0.36; P < 0.001) ratios. In multivariate linear regression analyses, older age, lower total cholesterol and higher HIV RNA were independently associated with higher NAG:UCr; older age, lower total cholesterol and lower CD4 cell count were independently associated with higher α1-M:UCr. CONCLUSIONS: In comparioson with HIV-negative participants, PLWH were more likely to have tubular injury. Early antiretroviral treatment might mitigate the development of kidney injury.

[Genetic diversity of Aedes albopictus populations in the coastal areas of southern China, using the microsatellite markers].

Objective: To analyze the genetic diversity of Aedes albopictus populations in the coastal areas of southern China by using the microsatellite markers to provide a basis for the control of vectors. Methods: Genetic diversity and clustering analysis of Aedes albopictus populations were studied in the 7 microsatellite loci, in Hangzhou, Ningbo and Yiwu of Zhejiang province, Longyan of Fujian province, Guangzhou of Guangdong province, Nanning of Guangxi Zhuang Autonomous Region and Haikou of Hainan province. Results: Numbers of different alleles (5.429-7.571), effective alleles (2.897-3.632), allele richness (5.236-7.170) and expected heterozygosity (0.538- 0.637) were detected from each of the Aedes albopictus population by using 7 microsatellite markers. The inbreeding coefficients appeared as 0.008-0.332, with heterozygote deficiency, in these populations. Fixation index of the whole populations was 0.058, suggesting that the genetic variation among the 7 populations was 5.8%. Data from the Neighbor-Joining clustering analysis showed that populations from Hangzhou and Yiwu belonged to one branch while Longyan and Guangzhou populations constituted another branch. Aedes albopictus populations of Nanning and Haikou showed great genetic variation but formed a single branch. Bayesian analysis on Aedes albopictus populations showed that the possible number of clusters was 3. Conclusions: Based on 7 microsatellite loci, relatively high genetic diversity and medium level of genetic differentiation that increasing with the geographical distances, were found in these Aedes albopictus populations, from the coastal areas in southern China.

[Detection of epidermal growth factor receptor mutations using bronchial washing fluid in lung cancer patients with negative results by rapid on-site evaluation].

Objective: To evaluate the clinical application of bronchial washing fluid (BWF) in the detection of epidermal growth factor receptor (EGFR) gene mutation in lung cancer patients during diagnostic bronchoscopic procedure. Methods: Patients with suspected lung cancer lesions but failed to be identified as malignancy by rapid on-site cytologic evaluation (ROSE) were enrolled. Performed blocker PCR for EGFR mutation detection using the supernatant and cell pellet of BWF samples and compared the detective results to the EGFR mutation status detected using histologic tumor samples. Results: A total of 85 BWF and paired histological samples were collected at Fudan University Affiliated Zhongshan Hospital from October 2016 to June 2017. There were 46 male and 39 female, with a mean age of 61 years (range 30-87 years). Thirty-one patients had benign diseases and 54 patients had primary lung cancer. Among these 54 lung cancer patients, the diagnoses were made basing on bronchoscopic biopsy samples in 31 patients. The detection rate of EGFR gene mutation in BWF samples was 100.0% concordant with that using histological samples.Another 23 cases whose bronchoscopic biopsy failed to establish malignant diagnoses were further identified by other sampling methods including surgical resection, lung biopsy, etc. A total of 15 patients were identified as EGFR mutated type by pathologic detection or clinically effect assessment, and BWF could detect 11 of them, accounting for 11/15 of all cases. Overall, BWF had achieved an overall accuracy of 95.3% (81/85) comparing to paired tumor histologic samples. Conclusions: BWF is an effective complementary specimen to bronchoscopic biopsy samples in EGFR gene mutation detection in patients with suspected lung cancer lesion and negative biopsy results evaluated by ROSE during bronchoscopy.

[Treatment of patients with different degree of acute respiratory distress syndrome caused by inhalation of white smoke].

Objective: To summarize the treatment experience of patients with different degree of acute respiratory distress syndrome (ARDS) caused by inhalation of white smoke from burning smoke bomb. Methods: A batch of 13 patients with different degree of ARDS caused by inhalation of white smoke from burning smoke bomb, including 2 patients complicated by pulmonary fibrosis at the late stage, were admitted to our unit in February 2016. Patients were divided into mild (9 cases), moderate (2 cases), and serious (2 cases) degree according to the ARDS Berlin diagnostic criteria. Patients with mild and moderate ARDS were conventionally treated with glucocorticoid. Patients with severe ARDS were sequentially treated with glucocorticoid and pirfenidone, and ventilator-assisted breathing, etc. were applied. The vital signs, arterial oxygenation index, changes of lung imaging, pulmonary ventilation function, general condition, and the other important organs/systems function were timely monitored according to the condition of patients. The above indexes were also monitored during the follow-up time of 10-15 months post injury. Data were processed with SPSS 18.0 statistical software. Results: (1) The symptoms of respiratory system of patients with mild and moderate ARDS almost disappeared after 3 days' treatment. Their arterial oxygenation index was decreased from post injury day 1 to 4, which almost recovered on post injury day 7 and completely recovered one month post injury. The symptoms of respiratory system of patients with severe ARDS almost disappeared at tranquillization condition 1-3 month (s) post injury. Their arterial oxygenation index was decreased from post injury day 3 to 21, which gradually recovered 1-3 month (s) post injury and was normal 15 months post injury. (2) Within 24 hours post injury, there was no obvious abnormality or only a little texture enlargement of lung in image of chest CT or X-rays of patients with mild and moderate ARDS. One patient with moderate ARDS had diffuse patchy and ground-glass like increased density shadow (pulmonary exudation for short) at post injury hour 96. Chest iconography of all patients with mild and moderate ARDS showed no abnormalities 10 months post injury. Both lungs of each of the two patients with severe ARDS showed obvious pulmonary exudation at post injury hours 45 and 75, respectively. One patient with severe ARDS showed no abnormality in chest image 10 months post injury, but there was still a small mesh-like increased density shadow in double lobes with slight adhesion of pleura in the other patient with severe ARDS 15 months post injury. (3) All patients showed severe restrictive hypoventilation when admitted to hospital. Pulmonary ventilation function of patients with mild and moderate ARDS recovered to normal one month post injury, and they could do exercises like running, etc. Pulmonary ventilation function of one patient with severe ARDS recovered to normal 6 months post injury, and the patient could do exercises like running, etc. The other patient with severe ARDS showed mild restrictive hypoventilation 15 months post injury and could do exercises like rapid walking, etc. (4) The condition of all mild and one moderate ARDS patients was better on post injury day 3, and they were transferred to the local hospital for subsequent treatment and left hospital on post injury day 21. One patient with moderate ARDS healed and left hospital on post injury day 29. Patients with severe ARDS healed and left hospital on post injury day 81. During the follow-up time of 10-15 months post injury, the other important organs/systems of all patients showed no abnormality, and there was no adverse reaction of glucocorticoid like osteoporosis, femoral head necrosis, or metabolic disorder. Two patients with severe ARDS did not have any adverse reaction of pirfenidone like liver function damage, photosensitivity, anorexia, or lethargy. Conclusions: Early enough and uninterrupted application of glucocorticoid can significantly reduce the ARDS of patients caused by inhalation of white smoke from burning smoke bomb. Sequential application of glucocorticoid and pirfenidone can effectively treat pulmonary fibrosis at the late stage.

[Long-term outcomes of off-pump coronary artery bypass grafting].

Objective: To investigate the long-term outcomes of off-pump coronary artery bypass grafting (OPCABG). Methods: Clinical data of 1 129 consecutive patients ( 937 males and 192 females) with coronary artery disease receiving OPCABG at Department of Cardiovascular Surgery, Chinese PLA General Hospital between January 2000 and December 2015 was retrospectively analyzed.The age of patients ranged from 29 to 83 years, with a mean age of (62.0±9.6) years. The follow-up data of the patients, including the graft patency and repeated revascularization rate, were analyzed. Results: Of the 1 129 patients analyzed, 1 059 cases (93.8%) were available for follow-up for 29-192 months[with a mean time of (95.6±34.1) months]. The 5-year, 10-year, 15-year and 16-year graft patency rate of arterial graft was 96.1%, 95.4%, 93.7% and 93.2%, respectively. The 5-year, 10-year, 15-year and 16-year graft patency rate of venous graft was 92.8%, 81.4%, 70.9% and 68.3%, respectively. During the follow-up, 69 (6.11%) patients underwent repeated revascularization procedures. Conclusion: OPCABG is safe and effective with a good long-term graft patency rate.

Outbreak of Occupational Brucellosis at a Pharmaceutical Factory in Southeast China.

Brucellosis is an occupational disease affecting workers in butcher shops, the milking and dairy product industry, causing more than 500 000 new cases around the world. As a national statutory B infectious disease in China, morbidity of brucellosis is rapidly increasing in recent years. We report an occupational outbreak of brucellosis infection in a pharmaceutical factory. Exposure was a result of manual operation in the process line, close contact with sheep placentas, insufficient disinfection and repeated using of protective suits and infected by aerosol dissemination. Improved preventive methods, appropriate public health measures and spread of health education would be helpful to prevent the occupational outbreak of brucellosis in future.

[Long-term outcome of surgical revascularization in patients with ischemic heart disease and left ventricular dysfunction].

OBJECTIVE: To analyze the long-term results and risk factors of surgical revascularization in patients with ischemic heart disease (IHD) and left ventricular dysfunction (LVD). METHODS: From January 2003 to July 2013, 2 132 patients underwent coronary artery bypass grafting (CABG) in our institution. Among them, 318 patients with LVD[left ventricular ejection fraction (LVEF) ≤50%]were included in the final study. There were 26 6 male and 52 female patients with age from 36 to 83 (63±9) years old. 76 patients underwent off-pump CABG (OPCAB) and 242 patients underwent conventional CABG (CCABG). Risk factors, perioperative results and follow-up data were collected and analyzed with cox hazard ratio model. RESULTS: Among 318 patients, 6 cases died of the operation with a hospital mortality of 1.9%. With follow-up time from 1 to 128(45.5±32.4)months, 25 patients were lost of follow-up, causing a follow-up rate of 92.0%. Among the 287 cases with long-term follow-up results, all-cause death, cardiogenic death and re-hospitalization due to heart failure were 14.6% (42/287), 5.9%(17/287), 14.6% (42/287), respectively. Re-revascularization rate, recurrent angina and myocardial infarction rate and cerebral incidence were 3.5%(10/287), 13.6% (39/287), 1.7%(5/287), respectively. The five-year survival rate was 85.6%. With all-cause death as the endpoint, preoperative LVEF (HR=0.943, 95%CI: 0.893-0.995, P=0.031) and perioperative implantation of IABP (HR=2.509, 95%CI: 1.051-5.992, P=0.038) emerged as the risk factors that affected the long term survival. The five-year survival rate of patients with severe LVD (LVEF≤35%) was significantly lower than that of patients with mild to moderate LVD (35%

A pediatric case of severe fever with thrombocytopenia syndrome in Zhejiang Province, China.

This report describes a pediatric case of severe fever with thrombocytopenia syndrome (SFTS), which is an emerging disease that is caused by a novel bunyavirus. Interestingly, the previously reported SFTS cases typically involved elderly patients, while our case involved a 5-year-old child from Zhejiang Province, China. In this report, we describe our investigation of the clinical and epidemiological characteristics of this case, to improve our understanding of this emerging disease. Our principle finding was that the present case's clinical symptoms were milder than those that have been reported in adult cases of SFTS. Therefore, we recommend more careful screening of pediatric patients who present with mild symptoms that are consistent with SFTS.

Seroprevalence of severe fever with thrombocytopenia syndrome virus in southeastern China and analysis of risk factors.

Severe fever with thrombocytopenia syndrome virus (SFTSV) has been prevalent for some time in China and it was first identified in 2010. However, the seroprevalence of SFTSV in the general population in southeastern China and risk factors associated with the infection are currently unclear. Blood samples were collected from seven counties across Zhejiang province and tested for the presence of SFTSV-specific IgG antibodies by ELISA. A total of 1380 blood samples were collected of which 5·51% were seropositive for SFTSV with seroprevalence varying significantly between sites. Seroprevalence of SFTSV in people who were family members of the patient, lived in the same village as the patient, or lived in a different village than the patient varied significantly. There was significant difference in seroprevalence between participants who bred domestic animals and participants who did not. Domestic animals are probably potential reservoir hosts and contact with domestic animals may be a transmission route of SFTSV.

[Patient-controlled analgesia with lornoxicam in patients undergoing gynecological surgery].

OBJECTIVE: To assess the analgesic effect and side effects of PCA with lornoxicam compared with morphine and tramadol. METHODS: 89 patients, scheduled for elective hysterectomy or hysteromyomectomy, were randomly divided into Group L, Group M and Group T. Three drugs administered i.v. via a patient-controlled analgesia for up to 24 h postoperatively. RESULTS: Efficacy was assessed by comparing total pain relief (TOTPAR) and sum of pain intensity difference (SPID) over 24 h. Statistically significant equivalence of lornoxicam, morphine and tramadol was shown by TOTPAR values 15.2 +/- 3.9, 16.4 +/- 3.5 and 15.9 +/- 4.4, by SPID values 10.3 +/- 3.1, 9.0 +/- 2.0 and 9.2 +/- 4.7, respectively (P > 0.05). Lornoxicam caused fewer adverse events than morphine and tramadol (10.0%, 26.7% and 17.2% of patients, respectively). CONCLUSION: The study suggests that lornoxicam provides an alternative to morphine or tramadaol for the treatment of postoperative pain.

[Isolation and cytological identification of a desynaptic variant in rice].

A sterile variant was found from the population of a japonica rice variety Lunhui 422. Cytological investigation was conducted in meiosis. It is showed that the sterility was caused by desynapsis. As there were 8.69 bivalents in average occurred to be desynaptic, moreover, the most number of the desynaptic bivalents reached 12 at post diakinsis. It can be considered that the desynaptic variation is a complete desynapsis found in rice so far.

p53 inactivating mutations in chinese breast carcinomas.

While previous reports on breast cancers indicate that Caucasian women have a low frequency of p53 mutations, higher frequencies of mutations are reported in some Japanese populations. There are few reports regarding p53 mutations in Chinese breast carcinomas. Using a previously established sensitive p53 yeast functional assay, we screened 23 Chinese breast carcinomas for mutations. The p53 was mutated in 5/23 (21.7%) specimens. Two of these mutations were detected in exon 5 and one was detected in each of exons 6, 7 and 8. All of these mutations have previously been shown to be mutated in Caucasian and Japanese breast cancers, but two have not previously been observed in Chinese breast cancers and one has also not been observed in Japanese.

Growth enhancement in transgenic Atlantic salmon by the use of an "all fish" chimeric growth hormone gene construct.

We have developed an "all fish" growth hormone (GH) chimeric gene construct by using an antifreeze protein gene (AFP) promoter from ocean pout linked to a chinook salmon GH cDNA clone. After microinjection into fertilized, nonactivated Atlantic salmon eggs via the micropyle, transgenic Atlantic salmon were generated. The presence of the transgene was detected by polymerase chain reaction (PCR) using specific oligonucleotide primers. A number of these transgenic fish showed dramatic increases in their growth rate. At one year old, the average increase of the transgenic fish was 2 to 6 fold and the largest transgenic fish was 13 times that of the average non-transgenic control.

The tcl-3 proto-oncogene altered by chromosomal translocation in T-cell leukemia codes for a homeobox protein.

The t(10;14)(q24;q11) chromosomal translocation found in malignant cells of 5-10% of patients with T-cell acute lymphoblastic leukemia (T-ALL) involves the T-cell receptor delta chain gene on chromosome 14 and a breakpoint cluster region on chromosome 10. The candidate proto-oncogene tcl-3, thought to be involved in the pathogenesis of t(10;14) T-ALL, was cloned and found to be elevated in expression in leukemic cells harboring the t(10;14) translocation. Sequence analysis revealed that tcl-3 is a new homeobox-containing gene. Comparison of the tcl-3 cDNA and its 5' genomic sequences with DNA sequences from the t(10;14) translocation breakpoints showed that this gene is structurally altered in four patients with t(10;14)(q24;q11) T-ALL. These findings suggest that homeobox-containing genes that normally act as transcription factors may contribute to T-cell leukemogenesis when abnormally expressed.

Structure and expression of the polyubiquitin gene in sea urchin embryos.

A cloned Lytechinus pictus cDNA has been identified, which includes seven direct repeats of a 228 bp sequence encoding ubiquitin and about 450 bp of 3' noncoding sequence. The deduced amino acid sequence is identical to that of ubiquitins of other animals (though repeats 3 and 5 each have single amino acid substitutions at different positions). Southern blot analysis revealed that the sea urchin genome contains a single copy of the polyubiquitin gene, and the number of 228 bp repeat units appears to vary from seven to ten among different alleles; no other ubiquitin coding sequences were detected. The size distribution of polyubiquitin mRNA is polymorphic among different individuals, probably corresponding to the differences in copy number of the repetitive coding sequence. The abundance of cytoplasmic polyubiquitin RNA is constant throughout embryogenesis and is similar in ectoderm, endoderm, and mesoderm cells. The constant prevalence of polyubiquitin mRNA apparently results from a balance between ontogenetic changes in its rate of synthesis and its stability in the presence of actinomycin D. Accumulation of polyubiquitin RNA was not heat shock-inducible during embryogenesis.

Multiple levels of regulation of tubulin gene expression during sea urchin embryogenesis.

The expression of the tubulin genes during embryogenesis of the sea urchin Lytechinus pictus has been analyzed. Single strand tracer excess titrations of alpha- and beta-tubulin mRNA and RNA gel blot hybridizations indicate that tubulin mRNA remains at a constant 1.3 X 10(5) transcripts per embryo during cleavage stages, increases during ciliogenesis shortly before hatching (12 hr PF), declines until midgastrula (30-35 hr PF), and then gradually increases 3-fold to about 6 X 10(5) per pluteus larva (72 hr PF). Tubulin synthesis changes in concert with its mRNA, except that during cleavage the relative rate of tubulin synthesis increases without a corresponding increase in tubulin mRNA abundance. The relative rates of tubulin gene transcription were assayed by a run-on assay in isolated nuclei. The synthesis of alpha- or beta-tubulin RNA results in little supplementation of maternal tubulin RNA during cleavage stages, but the rate increases at least 18-fold during ciliogenesis and then gradually decreases thereafter. The accumulation of tubulin mRNA after gastrulation can be accounted for by an ontogenetic increase in tubulin RNA stability, assayed by actinomycin D chase and RNA gel blot hybridization. The rates of synthesis, stabilities, and abundances of alpha- and beta-tubulin mRNAs were similar, suggesting coordinate regulation. These observations indicate the importance of translational regulation during cleavage, transcriptional regulation during ciliogenesis, and regulation of mRNA stability by the level of unpolymerized tubulin during later development.

Stabilization of tubulin mRNA by inhibition of protein synthesis in sea urchin embryos.

An increased level of unpolymerized tubulin caused by depolymerization of microtubules in sea urchin larvae resulted in a rapid loss of tubulin mRNA, which was prevented by nearly complete inhibition of protein synthesis. Results of an RNA run-on assay indicated that inhibition of protein synthesis does not alter tubulin gene transcription. Analysis of the decay of tubulin mRNA in embryos in which RNA synthesis was inhibited by actinomycin D indicated that inhibition of protein synthesis prevents the destabilization of tubulin mRNA. The effect was similar whether mRNA was maintained on polysomes in the presence of emetine or anisomycin or displaced from the polysomes in the presence of puromycin or pactamycin; thus, the stabilization of tubulin mRNA is not dependent on the state of the polysomes after inhibition of protein synthesis. Even after tubulin mRNA declined to a low level after depolymerization of microtubules, it could be rescued by treatment of embryos with inhibitors of protein synthesis. Tubulin mRNA could be induced to accumulate prematurely in gastrulae but not in plutei if protein synthesis was inhibited, an observation that is indicative of the importance of the autogenous regulation of tubulin mRNA stability during embryogenesis. Possible explanations for the role of protein synthesis in the control of mRNA stability are discussed.

Microtubule formation from maternal tubulins during sea urchin embryogenesis: measurement of soluble and insoluble tubulin pools.

The mass of tubulin protein in developing embryos of the sea urchin Lytechinus pictus was measured using a radiodilution immunoassay based on densitometric analysis of immunoprecipitated tubulins resolved electrophoretically. The tubulins constitute an average of 360 +/- 35 pg per egg, or 0.66% of the total protein, and there is no significant change in their concentration during embryogenesis. The masses of soluble and polymerized tubulin were measured for extracts prepared under conditions that stabilize microtubules. In eggs, a maximum of 14% of the tubulin is insoluble, and this increases throughout embryogenesis to 67% at pluteus stage (72 hr). The concentration of tubulin in eggs is at least 500 micrograms/ml, well above the critical concentration for tubulin assembly in vitro, yet microtubules have not been observed in eggs. The mass of newly synthesized tubulin, estimated from the mass of tubulin mRNA per embryo, accounts for a small fraction of the total tubulin by the end of gastrulation but for over half of the tubulin by the 72-hr pluteus stage. These observations are consistent with a model in which the declining level of unpolymerized tubulin controls the stability of tubulin mRNa, providing an autogenous regulation of the ontogenetic pattern of tubulin synthesis during sea urchin embryogenesis (Gong and Brandhorst, Development 102: 31-43).