Domains required for nucleic acid binding activities in chloroplast ribonucleoproteins.

Five ribonucleoproteins (or RNA-binding proteins) from tobacco chloroplasts have been identified to date; each of these contains an acidic N-terminal domain (24-64 amino acids) and two conserved RNA-binding domains (82-83 amino acids). All five ribonucleoproteins can bind to ssDNA and dsDNA but show high specificity for poly(G) and poly(U). Here we present the nucleic acid binding activity of each domain using a series of deletion mutant proteins made in vitro from the chloroplast 29 kDa ribonucleoproteins. The acidic domain does not have a positive effect on binding activities and proteins lacking this domain show higher affinities for nucleic acids than the wild-type proteins. Mutant proteins containing single RNA-binding domains can bind to poly(G) and poly(U), though with lower affinities than proteins containing two RNA-binding domains. The spacer region (11-37 amino acids) between the two RNA-binding domains does not interact with poly(G) or poly(U) by itself, but is required for the additive activity of the two RNA-binding domains. Proteins consisting of two RNA-binding domains but lacking the spacer have the same activity as those containing only one RNA-binding domain. Possible roles for each domain in chloroplast ribonucleoproteins are discussed.     

鹅掌楸种子和胚胎发育的研究

应用控制授粉、软 X-射线法、常规石蜡制片法和荧光检测等手段,研究了鹅掌楸(Lirio-dendron chinense(Hemsl.)Sarg.胚胎发育和控制授粉与结籽率的相关性。控制授粉后2小时花粉萌发,6小时萌发率最高,柱头可授期持续30小时左右。花粉管借助于柱头毛之间的分泌物进入柱头沟,经花柱沟、珠孔塞和珠心冠原进入胚囊,行珠孔受精。授粉后2周,胚乳为2至3细胞厚的狭组织;第6周,胚乳充满胚囊腔,珠心随之解体殆尽;第7到8周,球形胚、心形胚发生;第14到16周,子叶形成;第22周种子或熟,胚乳丰富。单株自然授粉结籽率不足1%。控制授粉后,单个聚合果的最高结籽率可达39%,9个聚合果的平均结籽率为17.7%。     

A genetic linkage map of 96 loci on the short arm of human chromosome 3.

We constructed a genetic map of 96 loci on the short arm of human chromosome 3 (3p) in 59 families provided by the Centre d'Etude du Polymorphisme Humaine (CEPH). Twenty-nine continuously linked loci were placed on the map with likelihood support of at least 1000:1; one locus, D3S213, was placed on the map with likelihood support of 871:1; D3Z1, an alpha satellite centromeric repeat probe, was placed on the map with likelihood support of 159:1; 65 loci were assigned regional locations. The average heterozygosity of the uniquely ordered markers was 49%. The map extends from 3p26, the terminal band of 3p, to the centromere (from D3S211 to D3Z1). Multipoint linkage analysis indicated that the male, female, and sex-averaged maps extend for 102, 147, and 116 cM, respectively. The mean genetic distance between uniquely ordered loci on the sex-averaged map was 4.0 cM. Probe density was greatest for the region of 3p between D3F15S2e and the telomere. The sex-averaged map contained two intervals greater than 10 cM. Seventeen probes were localized by fluorescence in situ hybridization. The loci described in this report will be useful in building an integrated genetic and physical map of this chromosome.     

Localized membrane depolarizations and localized calcium influx during electric field-guided neurite growth.

Our study explores the mechanisms behind neurite galvanotropism. Using phase, differential interference contrast and ratiometric fluorescence microscopy, we reveal four responses of N1E-115 mouse neuroblastoma cells to 0.1-1.0 mV/microns uniform DC electric fields: cathode-directed neurite initiation and elongation, cathode-biased growth cone filopodial protrusions, transient cathode-localized calcium increases, and persistent cathode-localized membrane depolarizations. These newly demonstrated events are temporally and spatially correlated, suggesting that they are causally related. The calcium increases are prevented by calcium channel blockers and by the removal of extracellular calcium. We therefore propose that the observed field-induced membrane depolarizations activate voltage-dependent calcium channels, resulting in cathode-localized calcium influx. This, in turn, may initiate the observed cathode-biased growth cone filopodial protrusions, followed by the cathode-directed neurite elongation.     

Simultaneous bilateral forearm revascularization

A successful simultaneous bilateral forearm revascularization was performed on a 17-year-old boy. Functional recovery of both forearms was evaluated 42 months after injury. The patient can use both hands for the activities of daily living. So far, he has been employed and has no significant psychological problems. Temporary intraluminal silicone shunts are extremely helpful for reducing ischemic damage to the injured limb. The sufficient skeletal shortening of the upper limb replantation is crucially important. The wounds must be managed by aggressive and repeated debridement. Accurate primary nerve repair is essential, and the early postoperative rehabilitation is also important to achieve a satisfactory functional return. The functional replanted or revascularized upper extremity is superior to an amputation or prosthesis, especially in the cases of bilateral upper extremity amputation or devascularization.     

Bioactivity of plasma prolactin in ovariectomized, diethylstilbestrol-treated Long-Evans and Holtzman rats after thyrotropin-releasing hormone or bromocriptine administration

The objective of this study was to determine the effects of thyrotropin-releasing hormone (TRH) and bromocriptine on plasma levels of biologically active prolactin in ovariectomized, diethylstilbestrol (DES)-treated rats. Female Long-Evans and Holtzman rats were ovariectomized and each was given a subcutaneous implant of diethylstilbestrol (DES). One week later, groups of DES-treated rats were fitted with indwelling intra-atrial catheters, and 2 days later blood samples were withdrawn before and at 1, 2, 5, 10, and 20 min after intravenous administration of TRH (250, 500, or 1000 ng/rat). Blood samples were obtained from other groups at 4 weeks of DES treatment by orbital sinus puncture under ether anesthesia before and at 30, 60, and 120 min after bromocriptine administration (2.5 mg/rat sc). Plasma was assayed for prolactin by conventional radioimmunoassay (RIA) and by Nb2 lymphoma bioassay (BA). Holtzman rats released significantly more prolactin following TRH than did Long-Evans rats when the RIA was used to measure prolactin. However, when the BA was used to assay prolactin in the same samples, the Long-Evans rats released more prolactin than did the Holtzman rats. In addition, the ratio of the BA to RIA values was significantly increased in both strains following TRH, but the greatest increase was observed in the Long-Evans rats, in which the ratio was 4.5 at the peak of the TRH-induced rise in plasma prolactin. Gel filtration chromatography of plasma obtained at 5 min after TRH treatment in Long-Evans rats revealed large molecular forms of prolactin with BA to RIA ratios of 4-5. In addition, monomeric prolactin had a BA to RIA ratio of 2. Bromocriptine treatment reduced prolactin levels in both strains, but the effect was more rapid in Holtzman than in Long-Evans rats. In addition, bromocriptine treatment of Holtzman, but not Long-Evans, rats significantly reduced the BA to RIA ratio of plasma prolactin. The results indicate that TRH and bromocriptine affect the release of biologically active prolactin to a greater extent than prolactin detected by antibody in the RIA, and that Long-Evans and Holtzman rats respond to these secretagogues differently with regard to BA to RIA comparisons.     

A comparison of plasma prolactin levels in young female Long-Evans and Holtzman rats as measured by Nb2 lymphoma bioassay and radioimmunoassay

This study was conducted to determine the plasma levels of prolactin in prepubertal and young, postpubertal, proestrus rats of mammary tumor-susceptible (Sprague-Dawley) and tumor-resistant (Long-Evans) strains using a sensitive bioassay-Nb2 lymphoma cell replication. Prepubertal Long-Evans rats had significantly higher levels of prolactin than did Holtzman Sprague-Dawley rats of the same age. Likewise, Long-Evans rats secreted significantly more prolactin into the blood on the afternoon and evening of proestrus than did Holtzman rats. Finally, ovariectomized Long-Evans rats released more prolactin into the blood at 1 day, but not at 8 or 15 days, of treatment with diethylstilbestrol. Prolactin levels determined by conventional radioimmunoassay and by bioassay were similar except on the afternoon of proestrus, when, in both strains of rats, the bioassay to radioimmunoassay ratio increased significantly above 1.0 during the late evening. In addition, the ratio was significantly less than 1.0 in the early and late afternoon in the Holtzman rats, but not Long-Evans rats. These data indicate that a strain of rats that is resistant to experimentally induced mammary cancer has higher prolactin levels in the blood than does a strain that is susceptible to mammary cancer at a time when mammary gland growth is rapid. Furthermore, there are times during the proestrus prolactin surge when the bioassay yielded higher and lower values of prolactin than radioimmunoassay of the same samples, suggesting functional heterogeneity of prolactin that may impact on mammary gland or other target tissue function.     

Production of cellulolytic enzymes from theXylaria andHypoxylon species of xylariaceae

Eighteen strains of xylariaceous fungi have been screened for higher activities of cellulolytic enzymes,Trichoderma reesei QM 9414 was also examined for comparison. Strains ofXylaria anisopleura andX. regalis had higher endocellulase (CMCase) and exocellulase (Avicelase) activities after 2 weeks' incubation.Hypoxylon stygium produced the highest activity of -glucosidase 3 days after inoculation. The optimum pH for these cellulolytic enzymes was approx. 5.0 and the optimum temperatures ranged from 37 to 50°C. A mixed culture process usingT. reesei QM 9414 andH. stygium was developed to obtain enhanced synthesis of cellulase. -Glucosidase activities in the mixed culture increased within 48h whenH. stygium was introduced after 24h.