Growth hormone, insulin-like growth factor I and the CNS: localization, function and mechanism of action

The growth hormone (GH) receptor and binding protein are synthesized in the CNS and are regulated differentially to their hepatic counterparts. GH is also synthesized in the CNS and is regulated differentially to its hypophyseal counterpart. Insulin-like growth factor I (IGF-I) is synthesized in the CNS and in the early postnatal period is regulated by peripherally secreted GH. Both GH and IGF-I alter the size and morphology of the CNS during development and affect differentiated cell function in the CNS, with consequent modulation of cognitive function. Differential utilization of the same signal transduction molecules indicates that GH and IGF-I possess distinct overlapping roles in CNS function.

13C NMR evidence for pyruvate kinase flux attenuation underlying suppressed acid formation in Bacillus subtilis

When batch and continuous Bacillus subtilis cultures are provided with a small amount of citrate, acid production ceases, carbon yield increases by more than 2-fold, and the productivity of recombinant protein increases. It has been hypothesized that pyruvate kinase activity is attenuated, which in turn lowers glucose flux and minimizes the acid overflow prompted by low Krebs cycle capacity. To complement existing enzyme activity, linear programming, and metabolite pool studies, (13)C NMR studies were performed. Atom mapping and isotopomer mapping matrix methods were used to select the best glucose label. "Best" was defined such that the NMR spectra of glutamate associated with metabolizing labeled glucose via the different candidate metabolic trafficking scenarios would differ considerably in fine structure (e.g., relative singlet intensities). When experiments were performed with 1-(13)C glucose, the observed NMR spectra corresponded well to the one predicted to arise when the metabolic trafficking occurs according to a pyruvate kinase attenuation scenario. This evidence further fortifies the prospects for successfully basing a metabolic engineering strategy on reducing pyruvate kinase activity to better match glycolytic and Krebs cycle capacities.

Preliminary study on the cleavage of fusion protein GST-CMIV with palladium(II) complex

A novel method for post-treatment of gene-engineered proteins is reported. A coden of Cys-His unit is introduced into the N-terminal of cecropin CMIV by using PCR. The gene is expressed in E. coli fused with GST. After purification, the fusion protein is cleaved by [Pd(en)(H2O)2]2+ at the His-Arg bond and the cecropin CMIV with antibacterial activity is obtained. The preliminary results held some promise of success for application of the palladium(II) complex as cleavage agent for the production of peptide drugs from gene-engineering fusion proteins.

Essential functions of protein tyrosine phosphatases PTP2 and PTP3 and RIM11 tyrosine phosphorylation in Saccharomyces cerevisiae meiosis and sporulation

Tyrosine phosphorylation plays a central role in eukaryotic signal transduction. In yeast, MAP kinase pathways are regulated by tyrosine phosphorylation, and it has been speculated that other biochemical processes may also be regulated by tyrosine phosphorylation. Previous genetic and biochemical studies demonstrate that protein tyrosine phosphatases (PTPases) negatively regulate yeast MAP kinases. Here we report that deletion of PTP2 and PTP3 results in a sporulation defect, suggesting that tyrosine phosphorylation is involved in regulation of meiosis and sporulation. Deletion of PTP2 and PTP3 blocks cells at an early stage of sporulation before premeiotic DNA synthesis and induction of meiotic-specific genes. We observed that tyrosine phosphorylation of several proteins, including 52-, 43-, and 42-kDa proteins, was changed in ptp2Deltaptp3Delta homozygous deletion cells under sporulation conditions. The 42-kDa tyrosine-phosphorylated protein was identified as Mck1, which is a member of the GSK3 family of protein kinases and previously known to be phosphorylated on tyrosine. Mutation of MCK1 decreases sporulation efficiency, whereas mutation of RIM11, another GSK3 member, specifically abolishes sporulation; therefore, we investigated regulation of Rim11 by Tyr phosphorylation during sporulation. We demonstrated that Rim11 is phosphorylated on Tyr-199, and the Tyr phosphorylation is essential for its in vivo function, although Rim11 appears not to be directly regulated by Ptp2 and Ptp3. Biochemical characterizations indicate that tyrosine phosphorylation of Rim11 is essential for the activity of Rim11 to phosphorylate substrates. Our data demonstrate important roles of protein tyrosine phosphorylation in meiosis and sporulation

[Spectral characteristics of solar radiation in broadleaved Korean pine forest in Changbai Mountain]

Based on the measurement above and below forest canopy and meteorological data, the spectral characteristics of solar radiation in broadleaved Korean pine forest in Changbai Mountain was analyzed. The results show that the photosynthetically active radiation(PAP) coefficients of total radiation, direct radiation and scatter radiation changed daily and yearly, with an annual averages of 0.46, 0.43 and 0.56 respectively. The average reflectivity, transmissitvity and absorptivity of single leaves of different tree species in Korean pine forest were 27.0%, 23.4%, 49.6% respectively. Single leaves nearly absorbed all of the ultraviolet radiation(UV) and 71.8% of photosynthetically active radiation, but transmitted 9.6% and reflected 18.6%. As for near-infrared radiation (NIR), the reflectivity and transmissitivity of leaves were a little less than the absorptivity. The forest canopy absorbed 93.9% PAR and 94.1% UV, but reflected and transmitted less. It absorbed 59.2%, reflected 26.3% and transmitted 14.4% NIR.

[The selection of fluoroacetate-resistant mutant from E. coli MMR204 and its influence on the expression of heterologous GL-7ACA acylase]

In the cultivation of gene engineered strain of Escherichia coli on glucose medium, excretion and accumulation of acetic acid inhibit not only cell growth but also the the expression of heterologous protein. It is obvious that the desirable host strain maintaining acetate at a low level is one of the approaches to increase the production of recombinant protein. The present article deals with the selection of mutants of E. coli DP19, DP8, which grow on the medium containing pyruvate as the sole carbon source in the presence of 50 mmol/L fluoroacetic acid. It is shown that mutant DP19 is defective in its phosphotransacetylase(PTA) activity and accumulates less acetate in the medium, while DP8 is defective in acetate kinase (ACK) and accumulates similar level of acetate comparing with its parent. Using pta- mutant E. coli DP19 as host, the expression of GL-7ACA acylase gene on the recombinant plasmid pMR24 is improved, and the yield of enzyme activity in flask fermentation is about twice as much as its parent.

Janus kinase 2-dependent activation of p38 mitogen-activated protein kinase by growth hormone. Resultant transcriptional activation of ATF-2 and CHOP, cytoskeletal re-organization and mitogenesis

We demonstrate here that p38 mitogen-activated protein (MAP) kinase is activated in response to cellular stimulation by human GH (hGH) in Chinese hamster ovary cells stably transfected with GH receptor cDNA. This activation requires the proline-rich box 1 region of the GH receptor required for JAK2 association and is prevented by pretreatment of cells with the JAK2-specific inhibitor AG490. ATF-2 is both phosphorylated and transcriptionally activated by hGH, and its transcriptional activation also requires the proline-rich box 1 region of the GH receptor. Expression of wild type JAK2 can further enhance hGH-induced ATF-2-, CHOP-, and Elk-1-mediated transcriptional activation, whereas pretreatment with AG490 is inhibitory. Use of either specific pharmacological inhibitors or transient transfection of cells with p38alpha MAP kinase cDNA or a dominant negative variant demonstrated that hGH-stimulated transcriptional activation of ATF-2 and CHOP, but not Elk-1, is regulated by p38 MAP kinase. Both the p38 MAP kinase and p44/42 MAP kinase are critical for hGH-stimulated mitogenesis, whereas only p38 MAP kinase is required for hGH-induced actin cytoskeletal re-organization. p38 MAP kinase is therefore an important regulator in coordinating the pleiotropic effects of GH.

A Two-Directional and Highly Convergent Approach for the Synthesis of the Tumor-Associated Antigen Globo-H

The assembly of six readily available building blocks in five glycosylation steps affords the tumor-associated Globo-H hexasaccharide 1 without the need for any intermediate protecting group manipulations. The aminopropyl spacer is employed for conjugation to carrier proteins.

[The development of a bilateral groove lengthener]

A new series of bilateral groove external fixator are introduced in the article, which are mainly used to treat limb crispation. These apparatuses are composed of the groove frame threaded rod, hooked bolts, nuts and pins. They can be adjusted in several directions to correct the axis of limb in limb lengthening. The pins can be fixed on the anterior and posterior sides of the frame, with a stable angle structure. The devices are light and practical, with multiple functions, low price, simple and convenient operation. It can apply to all kinds of hospitals.

Association of cystic fibrosis transmembrane conductance regulator and protein phosphatase 2C

Cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels are rapidly deactivated by a membrane-bound phosphatase activity. The efficiency of this regulation suggests CFTR and protein phosphatases may be associated within a regulatory complex. In this paper we test that possibility using co-immunoprecipitation and cross-linking experiments. A monoclonal anti-CFTR antibody co-precipitated type 2C protein phosphatase (PP2C) from baby hamster kidney cells stably expressing CFTR but did not co-precipitate PP1, PP2A, or PP2B. Conversely, a polyclonal anti-PP2C antibody co-precipitated CFTR from baby hamster kidney membrane extracts. Exposing baby hamster kidney cell lysates to dithiobis (sulfosuccinimidyl propionate) caused the cross-linking of histidine-tagged CFTR (CFTR(His10)) and PP2C into high molecular weight complexes that were isolated by chromatography on Ni(2+)-nitrilotriacetic acid-agarose. Chemical cross-linking was specific for PP2C, because PP1, PP2A, and PP2B did not co-purify with CFTR(His10) after dithiobis (sulfosuccinimidyl propionate) exposure. These results suggest CFTR and PP2C exist in a stable complex that facilitates regulation of the channel.

Targeted manipulation of maize genes in vivo using chimeric RNA/DNA oligonucleotides

Site-specific heritable mutations in maize genes were engineered by introducing chimeric RNA/DNA oligonucleotides. Two independent targets within the endogenous maize acetohydroxyacid synthase gene sequence were modified in a site-specific fashion, thereby conferring resistance to either imidazolinone or sulfonylurea herbicides. Similarly, an engineered green fluorescence protein transgene was site-specifically modified in vivo. Expression of the introduced inactive green fluorescence protein was restored, and plants containing the modified transgene were regenerated. Progeny analysis indicated Mendelian transmission of the converted transgene. The efficiency of gene conversion mediated by chimeric oligonucleotides in maize was estimated as 10(-4), which is 1-3 orders of magnitude higher than frequencies reported for gene targeting by homologous recombination in plants. The heritable changes in maize genes engineered by this approach create opportunities for basic studies of plant gene function and agricultural trait manipulation and also provide a system for studying mismatch repair mechanisms in maize.

[The effect of upon the stimulating action of glyburide in the islet cell secretion of insulin and its mechanism]

OBJECTIVE

To study the effect and mechanism of amylin upon oral sulfonylurea drugs and its action to stimulate the islet cell secretion of insulin in rats.

METHODS

Radioimmunogical and fluorescence methods were used to determine the amount of insulin secretion as well as the content of intracellular Ca(2+) of the rat islets incubated with amylin in different concentrations and followed by glyburide stimulation test.

RESULTS

In amylin concentrations of 5 micromol/L and 10 micromol/L, 3 nmol/L glyburide decreased insulin release volume, being (3.8 +/- 1.0) microg/L and (2.1 +/- 1.0) microg/L as compare with (4.9 +/- 0.9) microg/L of the control group (t = 2.313, P < 0.05; t = 5.887, P < 0.01). Intracellular Ca(2+) content in the two concentrations was (270 +/- 15) nmol/L and (130 +/- 15) nmol/L, being markedly decreased as compared with (330 +/- 18) nmol/L of the control group. The changes were dosage related (t = 7.243, P < 0.01; t = 24.143, P < 0.01).

CONCLUSION

High concentration of amylin is responsible for the prevention of the rise of Ca(2+) inside in the islet beta-cell acted upon by sulfonylurea drugs, this may be one of the mechanisms that bring about the decreased release of insulin.

Stoichiometry and kinetics of the high-affinity H+-coupled peptide transporter PepT2

Proton-coupled peptide transporters mediate the absorption of a large variety of di- and tripeptides as well as peptide-like pharmacologically active compounds. We report a kinetic analysis of the rat kidney high-affinity peptide transporter PepT2 expressed in Xenopus oocytes. By use of simultaneous radioactive uptake and current measurements under voltage-clamp condition, the charge to substrate uptake ratio was found to be close to 2 for both D-Phe-L-Ala and D-Phe-L-Glu, indicating that the H+:substrate stoichiometry is 2:1 and 3:1 for neutral and anionic dipeptides, respectively. The higher stoichiometry for anionic peptides suggests that they are transported in the protonated form. For D-Phe-L-Lys, the charge:uptake ratio averaged 2.4 from pooled experiments, suggesting that Phe-Lys crosses the membrane via PepT2 either in its deprotonated (neutral) or its positively charged form, averaging a H+:Phe-Lys stoichiometry of 1.4:1. These findings led to the overall conclusion that PepT2 couples transport of one peptide molecule to two H+. This is in contrast to the low-affinity transporter PepT1 that couples transport of one peptide to one H+. Quinapril inhibited PepT2-mediated currents in presence or in absence of external substrates. Oocytes expressing PepT2 exhibited quinapril-sensitive outward currents. In the absence of external substrate, a quinapril-sensitive proton inward current (proton leak) was also observed which, together with the observed pH-dependent PepT2-specific presteady-state currents (Ipss), indicates that at least one H+ binds to the transporter prior to substrate. PepT2 exhibited Ipss in response to hyperpolarization at pH 6.5-8.0. However, contrary to previous observations on various transporters, 1) no significant currents were observed corresponding to voltage jumps returning from hyperpolarization, and 2) at reduced extracellular pH, no significant Ipss were observed in either direction. Together with observed lower substrate affinities and decreased PepT2-mediated currents at hyperpolarized Vm, our data are consistent with the concept that hyperpolarization exerts inactivation effects on the transporter which are enhanced by low pH. Our studies revealed distinct properties of PepT2, compared with PepT1 and other ion-coupled transporters.

Growth hormone stimulates the formation of a multiprotein signaling complex involving p130(Cas) and CrkII. Resultant activation of c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK)

We have demonstrated previously that growth hormone (GH) activates focal adhesion kinase (FAK), and this activation results in the tyrosine phosphorylation of two FAK substrates, namely paxillin and tensin. We now show here in Chinese hamster ovary cells stably transfected with rat GH receptor cDNA that human (h)GH induces the formation of a large multiprotein signaling complex centered around another FAK-associated protein, p130(Cas) and the adaptor protein CrkII. hGH stimulates the tyrosine phosphorylation of both p130(Cas) and CrkII, their association, and the association of multiple other tyrosine-phosphorylated proteins to the complex. Both the c-Src and c-Fyn tyrosine kinases are tyrosine phosphorylated and activated by cellular hGH stimulation and form part of the multiprotein signaling complex as does tensin, paxillin, IRS-1, the p85 subunit of phosphatidylinositol 3-kinase, C3G, SHC, Grb-2, and Sos-1. c-Cbl and Nck are also tyrosine-phosphorylated by cellular stimulation with hGH and associate with the p130(Cas)-CrkII complex. c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) is activated in response to hGH in accordance with the formation of the abovementioned signaling complex, and hGH stimulated JNK/SAPK activity is increased in CrkII overexpressing NIH3T3 cells compared with vector transfected NIH3T3 cells. The formation of such a large multiprotein signaling complex by GH, with the resultant activation of multiple downstream effector molecules, may be central to many of the pleiotropic effects of GH.

High affinity Ca2+ binding sites of calmodulin are critical for the regulation of myosin Ibeta motor function

We coexpressed myosin Ibeta heavy chain with three different calmodulin mutants in which the two Ca2+-binding sites of the two N-terminal domain (E12Q), C-terminal domain (E34Q), or all four sites (E1234Q) are mutated in order to define the importance of these Ca2+ binding sites to the regulation of myosin Ibeta. The calmodulin mutated at the two Ca2+ binding sites in N-terminal domain and C-terminal domain lost its lower affinity Ca2+ binding site and higher affinity Ca2+ binding site, respectively. We found that, based upon the change in the actin-activated ATPase activities and actin translocating activities, myosin Ibeta with E12Q calmodulin has the regulatory characteristics similar to myosin Ibeta containing wild-type calmodulin, while myosin Ibeta with E34Q or E1234Q calmodulin lose all Ca2+ regulation. While the increase in myosin Ibeta ATPase activity paralleled the dissociation of 1 mol of calmodulin from myosin Ibeta heavy chain for both wild type (above pCa 5) and E12Q calmodulin (above pCa 6), the Ca2+ level required for the inhibition of actin-translocating activity of myosin Ibeta was lower than that required for dissociation of calmodulin, suggesting that the conformational change induced by the binding of Ca2+ at the high affinity site but not the dissociation of calmodulin is critical for the inhibition of the motor activity. Our results suggest that the regulation of unconventional myosins by Ca2+ is directly mediated by the Ca2+ binding to calmodulin, and that the C-terminal pair of Ca2+-binding sites are critical for this regulation.

Expression of matrix metalloproteinase-9 mRNA in osteoporotic bone tissues

Matrix metalloproteinases (MMPs), a sort of important enzymes involved in extracellular matrix metabolism, play critical roles in the process of tissues remodeling, wound healing and metastasis of tumors. Dot blot and in situ hybridization were used in this study to detect the expression and localization of MMP-9, an important proteolytic enzyme implicated in bone resorption in bone tissues. The results showed that the level of MMP-9 mRNA expression in osteoporotic bone tissues was significantly higher than that in normal control group and the cell types that expressed MMP-9 mRNA included mono- and multi-nuclear osteoclasts and some lining cells on the surface of bone matrix. It was suggested that MMP-9 play a key role in the development of bone loss in osteoporosis.

Expression of type-I collagen and matrix metalloproteinase-9 mRNA in bone of castrated adult female rats: effects of estrogen

OBJECTIVES

To elucidate the molecular changes of bone collagen during the development of postmenopausal osteoporosis and to investigate the molecular effects of estrogen replacement.

METHODS

An adult ovariotomy rat model was used. Type-I collagen and matrix metalloproteinase-9 (MMP-9) expressions in bone tissues of rats treated by sham surgery (SH), bilateral ovariotomy (OVX) and OVX with estradiol (OVX-E2) were analysed at mRNA level by using dot blot technique. The distribution of mRNA of these two genes in bone tissues was studied by in situ hybridization.

RESULTS

The expression levels of both type-I collagen and MMP-9 in bone tissues of OVX rats were higher than those of SH group, while treated with estradiol, the expression of both genes declined to some degree. In situ hybridization showed that type-I collagen mRNA located in osteoblasts, whereas MMP-9 was mainly expressed in osteoclasts, some lining cells on bone surface, and some mononuclear cells in bone marrow.

CONCLUSIONS

The reduction of high bone turnover in osteoporotic bone tissues induced by estrogen replacement may result from alterations in gene expression related to bone formation and bone resorption. These alterations are consistent with the changes observed previously by histomorphometry and biochemical markers of bone metabolism on OVX animals and postmenopausal osteoporosis.

Growth hormone stimulates the tyrosine phosphorylation and association of p125 focal adhesion kinase (FAK) with JAK2. Fak is not required for stat-mediated transcription

We have demonstrated that growth hormone (GH) activates focal adhesion kinase (FAK), and this activation results in the tyrosine phosphorylation of two FAK substrates, paxillin and tensin. The activation of FAK is time-dependent (maximal activation at 5-15 min) and dose-dependent (maximal activation at 0.05 nM). FAK and paxillin are constitutively associated in the unstimulated state, remain associated during the stimulation phase, and recruit tyrosine-phosphorylated tensin to the complex after GH stimulation. Half of the carboxyl-terminal region of the GH receptor is dispensable for FAK activation, but FAK activation does require the proline-rich box 1 region of the GH receptor, indicative that FAK is downstream of JAK2. FAK associates with JAK2 but not JAK1 after GH stimulation of cells. Using FAK-replete and FAK-deficient cells, we also show that FAK is not required for STAT-mediated transcriptional activation by GH. The use of FAK in the signal transduction pathway utilized by GH may be central to many of the pleiotropic effects of GH, including cytoskeletal reorganization, cell migration, chemotaxis, mitogenesis, and/or prevention of apoptosis and gene transcription.

An African HIV-1 sequence from 1959 and implications for the origin of the epidemic

There is considerable genetic diversity among viruses of different subtypes (designated A to J) in the major group of human immunodeficiency virus type 1 (HIV-1), the form of HIV that is dominant in the global epidemic. If available, HIV-1 sequences pre-dating the recognition of AIDS could be crucial in defining the time of origin and the subsequent evolution of these viruses in humans. The oldest known case of HIV-1 infection was reported to be that of a sailor from Manchester who died of an AIDS-like illness in 1959; however, the authenticity of this case has not been confirmed. Genetic analysis of sequences from clinical materials obtained from 1971 to 1976 from members of a Norwegian family infected earlier than 1971 showed that they carried viruses of the HIV-1 outlier group, a variant form that is mainly restricted to West Africa. Here we report the amplification and characterization of viral sequences from a 1959 African plasma sample that was previously found to be HIV-1 seropositive. Multiple phylogenetic analyses not only authenticate this case as the oldest known HIV-1 infection, but also place its viral sequence near the ancestral node of subtypes B and D in the major group, indicating that these HIV-1 subtypes, and perhaps all major-group viruses, may have evolved from a single introduction into the African population not long before 1959.

Clinical study on chronopharmacokinetics of digoxin in patients with congestive heart failure

Fluorescence polarization immunoassay was used to study the chronopharmacokinetics of digoxin in 10 patients with congestive heart failure (CHF) who also served as self-controls. Our results showed that the serum digoxin concentration reached peak value 1 h after taking digoxin at 7:00 a.m., but the serum digoxin concentration reached the peak value 2 h after taking digoxin at 4:00 p.m. The average serum digoxin concentration area under curve was greater and the best maintainable time of serum concentration within 24 h after taking digoxin at 4 p.m. longer than those at 7:00 a.m. The heart rates were obviously lower and the cardiac function was significantly improved in 4:00 p.m. group.

Perception of foreign cigarettes and their advertising in China: a study of college students from 12 universities

OBJECTIVE

To examine how deeply foreign cigarette advertising had penetrated the Chinese market when a new ban on cigarette advertising was enacted in February 1995.

DESIGN

A survey using self-completion questionnaires administered in college classrooms from November 1994 to March 1995.

SETTINGS

Eight universities and four medical schools in three Chinese cities: Beijing, Wenzhou, and Hangzhou.

SUBJECTS

1896 college students who agreed to complete a written questionnaire. The mean age was 21.2 years; 39.5% of respondents were female.

RESULTS

Four of the top eight cigarette brands most familiar to the respondents were foreign: Marlboro, 555, Kent, and Hilton. Advertisements for the foreign brands were much more likely to be seen than those for the domestic brands; those for Marlboro were reported most often (29.7%), followed by 555 (21.8%) and Kent (18.1%). Among smokers, Marlboro was the most preferred foreign brand, by 44.2%. The preference for Marlboro was also correlated with smokers having seen its advertisements. Most respondents, 71.8%, believed that cigarette advertising should be banned.

CONCLUSIONS

The previous restrictions on cigarette advertising in China failed to prevent a large portion of the population from seeing and understanding the advertisements. Before the 1995 advertising ban took effect, strict limitations on imports of foreign cigarettes notwithstanding, certain highly advertised brands such as Marlboro achieved wide recognition and even consumer preference. Stricter restrictions are suggested as previous ones have failed to achieve their intended effects.

Studies on the ossification of compound transplantation of porous TCP ceramics and bone marrow

Following the culture of human red marrow with porous TCP ceramics in vitro, a large amount culturing marrow cells adhered well to the surface and inner wall of TCP ceramics and spread well over the dish bottom 4 weeks after cultivation. After the compound transplantation of porous TCP ceramics with red marrow into quadriceps femoris muscle of rabbits, a huge amount of new bone and marrow formed in these sites on and in the ceramics 4 weeks after transplantation. These results showed an excellent biocompatibility between TCP ceramics and marrow and an excellent osteogenic effect in the compound transplantation. The mechanism of ossification and clinical significance about the compound transplantation were discussed.

The STR120 satellite DNA of soybean: organization, evolution and chromosomal specificity

A highly repeated DNA sequence family, STR120, with tandemly arranged repetitive units (monomers) of approximately 120bp, has been identified in soybean [Glycine max (L.) Merr.]. Five related clones showing tandem repeats of a 120-bp-long monomer were isolated from a soybean genomic library. Results of Southern blotting experiments using three of the clones as probes onto genomic DNA digested with different restriction enzymes were in agreement with a tandem arrangement of these sequences in the genome. A total of 12 monomers were sequenced, showing considerable sequence heterogeneity. A consensus sequence of 126 bp was obtained that exhibits an average similarity of 81% to the sequenced units. In three of the clones identified, neighbouring units are significantly more similar to each other than to units from different clones; in the remaining two clones, however, similarity between the two units observed is low (70%), while the overall similarity between the two clones is high (95%). This indicates that in these cases the repetitive unit may be the dimer rather than the monomer. Based on the presence of direct repeats within each monomer, we suggest that the 120-bp monomer may itself have evolved by duplication of an ancestral 60-bp unit. The STR120 family distribution is limited to annual soybeans and is not found, at least at high-copy number, in related perennial soybeans or other members of the tribe Phaseolae. Fluorescence in situ hybridization (FISH) to metaphase chromosomes using four of the clones as probes shows that the number of chromosomal locations differs depending on the stringency conditions and goes from two to eight when the stringency is progressively lowered. The estimated copy number for one of the clones is from 5000 to 10000, but this may just represent a lower boundary for the whole family in consideration of the high sequence divergence observed within the family. FISH and sequence analysis therefore indicate that different subfamilies as well as higher-order repeat units are present in the STR120 family, very much like those in primate alpha satellite DNA, and that some of the subfamilies seem to exhibit divergence on a chromosomal basis.

[Colour Doppler ultrasonographic indices in predicting fetal hypoxia and acidosis]

OBJECTIVE

To evaluate the effect of uterine-placental-fetal blood flow velocity waveforms (FVWs) on predicting fetal hypoxia and acidosis in high risk pregnancy.

METHODS

46 women of normal term pregnancy (normal group) and 32 women of high risk term pregnancy (high risk group) were examined with colour Doppler ultrasound for their FVWs including maternal uterine artery (UtA), fetal umbilical artery (UmA), middle cerebral artery (MCA), and renal artery (RA). Umbilical artery blood gases were analysed at delivery in high risk group.

RESULTS

The resistance index (RI), pulsatile index (PI) and ratio of peak systolic to least diastolic flow velocity (S/D) of UtA, UmA and RA were higher and the PI, S/D of MCA was lower significantly in the high risk group than that of normal the group (P < 0.05). In the high risk pregnancy, when UmA PO2 was less than 2.5 kPa, the S/D of UtA, PI, S/D of UmA and RI, PI, S/D of RA were increased, and the PI of MCA was decreased (P < 0.05). There were a positive correlation between PI of UmA, RA and PO2 pH of UmA, and a negative correlation between the former and PCO2 of UmA. But there were a negative correlation between PI of MCA and PO2, pH of UmA, and a positive correlation between the former and UmA PCO2.

CONCLUSION

In the high risk pregnancy, fetal cerebral blood flow increased, whereas blood flow of fetal peripheral vessels (especially renal vessel) decreases. There is a good correlation between fetal hypoxia and fetal blood FVWs. The indices of the fetal blood FVMs can identify fetal hypoxia and acidosis.

[Research on omni-directional ultrasonic imaging]

In this paper, an omni-direction M-mode ultrasonic imaging method is introduced, in which M-mode sample line can rotate and move freely. In this way the measurement of parameters such as amplitude and speed of movement of organs can be conducted in any position or direction. We analyzed the sources of errors of the method and the way to overcome them.

The interconversion of protein phosphatase 2A between PP2A1 and PP2A0 during retinoic acid-induced granulocytic differentiation and a modification on the catalytic subunit in S phase of HL-60 cells

Alterations in protein phosphatase 2A (PP2A) during retinoic acid-induced differentiation of HL-60 cells have been investigated. PP2A activity of HL-60 cells for phosphorylated myelin basic protein showed a sharp and transient increase after 18-h treatment with 1 microM retinoic acid, which corresponded to G1/S boundary of the cell cycle. This PP2A of the 18-h treated cells was eluted from a DEAE-Sepharose column with 0.13 M NaCl, while PP2A from control cells was eluted with 0.23 M NaCl. The phosphorylase phosphatase activity of PP2A in the 0.13 M eluate was greatly enhanced in the presence of protamine compared with that of the later eluting PP2A. Immunoblot analyses with antisera against B' and B alpha subunits showed that the PP2A in the 0.13 M NaCl eluate from 18-h retinoic acid-treated cells was PP2A0 (AC-B'), whereas the PP2A eluted with 0.23 M NaCl from 24-h retinoic acid-treated cells and 0-, 18-, and 24-h control cells was PP2A1 (AC-B alpha). These results strongly suggest that PP2A undergoes a transient and reversible interconversion of holoenzyme forms during the initial stage of retinoic acid-induced granulocytic differentiation. PP2A activity assayed after dissociation of the catalytic subunit, for phosphorylase as substrate, showed a sharp and transient decrease in S phase of HL-60 cells irrespective of the presence or absence of retinoic acid. Immunoblot analyses with antisera against C-terminus and N-terminus of the catalytic subunit of PP2A suggested that a modification at the C-terminus is responsible for the decrease in PP2A activity. Immunoreactivity to the C-terminal antibody was restored after treatments of the S-phase extract with alkali or ethanol, the conditions which remove the methyl group from the C-terminus. These results suggest that the C-terminus of PP2A catalytic subunit is transiently methylated in S phase of HL-60 cells.

Tissue response and the cytoconduction ability to collagen/hydroxyapatite heterotopic implantation

A histological and ultrastructural observation of CHA implanted intramuscularly and subcutaneously had been reported. Our results showed that a mild inflammation developed at the early stage and disappeared 2 weeks after implantation. The infiltrating cells were mainly monocyte-macrophages, a number of fibroblasts followed macrophages closely. It was possible that as CHA degrades, monocyte-macrophages continuously released inflammatory factors, thus enhancing fibroblast proliferation activity and tissue regeneration. In addition, the heterotopic calcification of collagen matrix was observed, suggesting that CHA promoted calcification deposition.

[The study of the morphology of ultramicrostructure in molecular level of nucleus herniation of lumbar intervertebral disc]

In order to investigate the morphology of ultramicrostructure in molecular level of nucleus herniations, the authors studied the ultramicrostructure of three cases of nucleus herniations of lumbar intervertebral disc which were proved by operations and one case of normal nucleus pulposus of fresh corpse by using of atomic force microscope. The results showed that the arrangement of collagen bundle, collagen fiber and procollagen fiber were different between the two conditions, and the morphology of molecular particles of proteoglycan in nucleus herniations was different from that in the normal condition. In the condition of nucleus herniations, the collagen fiber formed procollagen fiber reticular porous adhering to the molecules of protein and proteoglycan, and the DNA adhering to the monochain of RNA in fiberal cell nuclei, in the form of bichain and multichain three dimensions helix structures. The banded structure (64-78 mm) of the procollagen fiber, and the collagenation and calcification of the degenerated nuclens pulposuses, the quantity of which was significant greater than normal (P < 0.05) indicated that the chronic injury of lumbar intervertebral nucleus pulposuses gave rise to the injury and break of the collagen fiber which resulted in twist (tangle) phenomenon so that nucleus pulposuses lost their normal resistance strength.

Characterization and application of soybean YACs to molecular cytogenetics

Yeast artificial chromosomes (YACs) are widely used in the physical analysis of complex genomes. In addition to their value in chromosome walking for map-based cloning, YACs represent excellent probes for chromosome mapping using fluorescence in situ hybridization (FISH). We have screened such a library for low-copy-number clones by hybridization to total genomic DNA. Four clones were chosen for chromosome tagging based upon their low or moderate signal. By using degenerate oligonucleotide-primed PCR (DOP-PCR), we were able to use relatively small amounts of soybean YAC DNA, isolated directly by preparative pulsed-field gel electrophoresis, as FISH probes for both metaphase chromosome spreads and interphase nuclei. FISH chromosomal analysis using the three of the clones as probes resulted in relatively simple hybridization patterns consistent with a single homologous locus or two homoeologous loci. The fourth YAC probe resulted in a diffuse hybridization pattern with signal on all metaphase chromosomes. We conclude that YACs represent a valuable source of probes for chromosomal analysis in soybean.

Soybean chromosome painting: a strategy for somatic cytogenetics

Cytological identification of soybean mitotic metaphase chromosomes (2n = 40) has been severely limited by their small size and uniform karyomorphology. We have developed fluorescent in situ hybridization (FISH), PCR-primed in situ labelling (PCR-PRINS) procedures, and molecular probes for routine cytological identification and for the physical mapping of soybean somatic chromosomes. Chromosome preparation has been achieved by modifications of previous protocols and through the preparation of root-tip protoplasts prior to chromosome spreading. Initially our probe selection focused on highly repeated DNAs that provide very intense localized hybridization signals. Repetitive gene probes that have proven valuable include the rDNA loci (5S and 45S) which are chromosome specific. We have also developed satellite DNA probes for two different sequence families: the SB92 and the STR120 satellites. Both of these are tandemly arranged at multiple chromosomal loci. By using different cloned examples of each family, we have been able to selectively label unique subsets of soybean chromosomes. Double hybridization with biotin and digoxigenin labeled probes has allowed us to determine the chromosomal overlap between different probes. In addition, we have joined portions of the metaphase chromosome painting patterns with the genetic map by single-copy FISH and PCR-PRINS detection of the RFLP loci G8.15, G17.3, and A199a and A199b. Total genomic DNA in situ hybridization (GISH) patterns were also used to characterize the soybean chromosomes.

Ribosomal RNA genes in soybean and common bean: chromosomal organization, expression, and evolution

Ribosomal RNA (5S and 45S) genes were investigated by FISH in two related legumes: soybean [Glycine max (L.) Merr.] and common bean (Phaseolis vulgaris L.). These species are both members of the same tribe (Phaseoleae), but common bean is diploid while soybean is a tetraploid which has undergone diploidization. In contrast to ploidy expectations, soybean had only one 5S and one 45S rDNA locus whereas common bean had more than two 5S rDNA loci and two 45S rDNA loci. Double hybridization experiments with differentially labelled probes indicated that the soybean 45S and 5S rDNA loci are located on different chromosomes and in their distal regions. Likewise, the common bean 45S and 5S rDNA loci were on unique chromosomes, though two of the 5S rDNA loci were on the same chromosome. FISH analysis of interphase nuclei revealed the spatial arrangement of rDNA loci and suggested expression patterns. In both species, we observed one or more 5S rDNA hybridization sites and two 45S rDNA hybridization sites associated with the nucleolar periphery. The 45S rDNA hybridization patterns frequently exhibited gene puffs as de-condensed chromatin strings within the nucleoli. The other condensed rDNA sites (both 5S and 45S) were spatially distant from the nucleolus in nucleoplasmic regions containing heterochromatin. The distribution of rDNA between the nucleoplasm and the nucleoli is consistent with differential gene expression between homologous alleles and among homoeologous loci.

Genetic characterization of human immunodeficiency virus type 1 in blood and genital secretions: evidence for viral compartmentalization and selection during sexual transmission

To explore the mechanism of sexual transmission of human immunodeficiency virus type 1 (HIV-1), we compared HIV-1 gp120 sequences in longitudinal samples from five acute seroconvertors with those from their corresponding sexual partners (transmitters). We used a quantitative homoduplex tracking assay to compare the overall genetic composition of HIV-1 quasispecies in each transmission pair and to track the transmitted viruses during the acute and asymptomatic stages of HIV-1 infection. In the chronically infected transmitters, HIV-1 variants in genital secretions differed from those in blood and variants in cells differed from those in cell-free plasma, indicating remarkable sequence heterogeneity in these subjects as well as compartmentalization of the virus in different bodily sites. Conversely, two of five seroconvertors had only a few related variants and three of five harbored only one viral population, indicating that in these subjects the transmitted viruses were typically homogeneous. Transmitted viruses were evident in the donor's seminal plasma (one of five cases) and even more so in their seminal cells (three of five cases), suggesting that both cell-associated and cell-free viruses can be transmitted. In every pair studied, the transmitted variant(s) represents only a minor population in the semen of the corresponding transmitter, thereby providing evidence that HIV-1 selection indeed occurs during sexual transmission.

Sperm Identification in Maize by Fluorescence in Situ Hybridization

The two sperm cells of common origin within the pollen tube of flowering plants are each involved in a fertilization event. It has long been recognized that preferential fusion of one sperm with the egg can occur in B chromosome-containing lines of maize. If the second pollen mitosis begins with a single B chromosome, nondisjunction will result in one sperm possessing two B chromosomes and the other containing no B chromosomes. The B chromosome-containing sperm most often fertilizes the egg, whereas the sperm nucleus with no B chromosomes fuses with the polar nuclei. Despite the obvious advantages of being able to recognize and then track, separate, and analyze one sperm type from the other, it has not been possible because of the lack of sufficient detectable differences between the two types of sperms. In this study, we used a B chromosome-specific DNA sequence (pZmBs) and in situ hybridization to identify and track the B chromosome-containing sperm cell within mature pollen and pollen tubes. Our results are consistent with conclusions from previous genetic studies related to B chromosome behavior during pollen formation. Within pollen tubes, the position in which the B chromosome-containing sperm travels (leading or trailing) in relation to the sperm cell lacking B chromosomes appears to be random.

[Alterations of protein phosphatases, PP2A and PP1, during retinoic acid-induced differentiation of HL-60 cells]

Alterations of protein phosphatases, PP2A and PP1, during the retinoic acid-induced differentiation of HL-60 cells have been investigated. The PP2A activity determined with myelin basic protein (MBP) as a substrate showed a sharp transient increase at 18 h of incubation of the cells with retinoic acid, whereas during incubation without retinoic acid, the activity remained at the initial level. On DEAE-Sepharose column chromatography of the extracts preparted from the cells incubated without retinoic acid, the PP2A activities determined with MBP were eluted at 0.13 M or 0.23 m NaCl, respectively. The PP2A activity of the cells incubated for 18 h with retinoic acid was much more greatly activated by protamine compared with the activity of the cells incubated without retinoic acid. These results strongly suggest a conversion of PP2A holoenzyme from PP2A1 to PP2A0 during the initial process of the retinoic acid-induced differentiation. On the other hand PP2A activity determined with phosphorylase alpha as a substrate showed a sharp transient decrease at 24 h of incubation of the cells, irrespective of the presence or the absence of retinoic acid in the incubation mixtures. This decrease may be related to the synchronization of the cells at S phase, which also occurred irrespective of the retinoic acid stimulation. PP1 activity determined with MBP was transiently increased between 27 and 36 h of the incubation of cells without retinoic acid. The increase was strongly suppressed in the cells incubated with retinoic acid, suggesting a role of PP1 in the cell proliferation, the activity of which was also inhibited by retinoic acid.

Epiphyseal lengthening operation--an improved technique

An improved method of epiphyseal lengthening operation and subsequent outer fixation are presented on the basis of experience in 30 cases. The operative technique is described in detail, including the different options of separative traction and osteotomy at subtrochanteric, distal part of the upper femur and lower tibial levels. The physiological and histological research concerning this method is discussed. The authors believe that this procedure is better than the other methods.

Hybridization properties of oligodeoxynucleotide pairs bridged by polyarginine peptides

The hybridization properties of a series of probes, based on two 9mer oligodeoxynucleotides (designated as I and II) having an appended oligoarginine chain (Rn) to produce peptide-oligonucleotide conjugates or peptide-bridged oligonucleotide pairs (e.g. Rn-I or II-Rn-I), were investigated. For the double-linked probes, we found that the peptide bridge induces the two 9mers to bind complementary single-stranded DNA or RNA targets with substantially enhanced thermal stability. The resulting hybrid with complementary DNA was found to assume a 1:1 complex in the B conformation as judged by UV mixing curves and CD spectroscopy. Complexes of single or double-linked probes with complementary RNA exhibited sensitivity to RNase H digestion. The influence of the identity and chirality of the repeating unit in the bridge, the length of the bridge, the gap size and the salt concentration on the hybridization properties of this new class of oligonucleotide probes was also studied. Our data reveal that these compounds exhibit properties that should prove useful in the development of antisense strategies.

Functional expression of mammalian myosin I beta: analysis of its motor activity

The motor function of vertebrate unconventional myosins is not well understood. In this study, we initiated the baculovirus expression system to characterize a novel myosin I from bovine adrenal gland that we had previously cloned [Zhu, T., & Ikebe, M. (1994) FEBS Lett. 339, 31-36], which is classified as myosin I beta. The expressed myosin I beta was well extracted when calmodulin was coexpressed in Sf9 cells. The recombinant myosin I beta cosedimented with actin in an ATP dependent manner. The purified myosin I beta was composed of one heavy chain and three calmodulins. The electron microscopic image of myosin I beta confirmed its single-headed structure with a short tail, which is similar to that of brush border myosin I (BBMI). Myosin I beta showed high K+,EDTA--ATPase activity (approximately 0.14 mumol/min/mg) and Ca(2+)-ATPase activity (approximately 0.32 mumol/min/mg), and the KCl/pH dependence of these activities was different from that of conventional myosin. Mg(2+)-ATPase activity of myosin I beta alone was increased above pCa 6, while the actin dependent activity was not affected by Ca2+. Actin sliding velocity of myosin I beta in the absence of Ca2+ was 0.3-0.5 microns/s at 25 degrees C, which is much greater than that of BBMI (< 0.05 microns/s). The actin sliding activity was abolished above pCa 6, and the sliding activity was restored when exogenous calmodulin was added in the absence of Ca2+. Within similar Ca2+ concentrations, one of the three calmodulins was dissociated from myosin I beta. The results suggest that Ca2+ dependent association of calmodulin may function as a regulatory mechanism of myosin I beta motor activity and that the motor activity of mammalian myosin I is largely different among distinct myosin I isoforms.

[The cloning and analysis of a single gene in Drosophila homologic with human oncogene TTG]

The human TTG/RBTN family is an oncogene family. There are three members in this family: TTG-1/RBTN-1, TTG-2/RBTN-2 and TTG-3/RBTN-3. Two of them, TTG-1/RBTN-1 and TTG-2/RBTN-2 have been isolated at the sites of chromosomal translocations in T-cell leukaemia. This gene family encodes cysteine-rich proteins with two tandem copies of a LIM motif. The function of the LIM motif is unknown. We found that the TTG-2 gene is highly conserved among mammals; Drosophila and yeast. As a first step to obtain a model system for studying the function of the LIM motifs, we isolated the Drosophila homologue dttg. In contrast to human, Drosophila appeared to have only one ttg/rbtn gene. A 2087bp cDNA clone was isolated, encoding a protein of 266 amino acids. A second transcript with an alternative 5' end was identified in RNA from embryos. The Drosophila ttg protein consisted of two tandem copies of the conserved LIM domain characteristic of the human TTG/RBTN family. The amino acid sequence similarity with human TTG-1 and TTG-2 is 79% and 62%, respectively. The dttg, like TTG-1, have an intron in the second LIM encoding region, which is not present in TTG-2.