Search

Natural rubber is one of the most important polymers produced by plants because it is strategic raw material used in more than 40000 products including the tire. It is focused as carbon neutral industrial material because it is synthesized from atmospheric CO2. Among over 2500 rubber producing plant species, the Para rubber tree (Hevea brasiliensis Muell. Arg.) is presently the only commercial source of natural rubber. There are some unknown points about the detail of natural rubber biosynthesis. The objective of this review is to provide readers with information on the newest trends of the natural rubber and Para rubber tree research from standpoint of biochemistry and molecular biology.

Plastid transformation offers several unique advantages compared with nuclear genome transformation, such as high level of transgene expression within plastids, expressing multiple transgenes as operons, lack of position effect due to site-specific transgene integration, and reducing risks of gene flow via pollen due to maternal inheritance of the plastid genome. Plastid transformation has been applied to several herbal species, but as yet there are no applications to tree species. We report here the first successful plastid transformation in a tree species, Populus alba. A vector for plastid transformation of poplar (Populus alba) was constructed, which carried the spectinomycin resistance gene and the green fluorescence protein gene as marker genes. In the regenerated shoots, the site-specific integration of foreign genes and the establishment of a high homoplastomic state were confirmed. Immunoblot analysis and histological observations corroborated the accumulation of green fluorescence protein in chloroplasts. The establishment of a plastid transformation system in poplar provides a novel tool for tree biotechnology.

Transgenic plastids offer unique advantages in plant biotechnology, including high-level foreign protein expression. However, broad application of plastid genome engineering in biotechnology has been largely hampered by the lack of plastid transformation systems for major crops. Here we describe the development of a plastid transformation system for lettuce, Lactuca sativa L. cv. Cisco. The transforming DNA carries a spectinomycin-resistance gene (aadA) under the control of lettuce chloroplast regulatory expression elements, flanked by two adjacent lettuce plastid genome sequences allowing its targeted insertion between the rbcL and accD genes. On average, we obtained 1 transplastomic lettuce plant per bombardment. We show that lettuce leaf chloroplasts can express transgene-encoded GFP to approximately 36% of the total soluble protein. All transplastomic T0 plants were fertile and the T1 progeny uniformly showed stability of the transgene in the chloroplast genome. This system will open up new possibilities for the efficient production of edible vaccines, pharmaceuticals, and antibodies in plants.

難治性右下腿潰瘍を契機に診断された腹部限局型解離性大動脈瘤の1例を経験したので報告する.症例は62歳,男性.高血圧症,高脂血症の既往がある.左下肢蜂窩織炎と吐血を主訴に他院に入院した.入院後,髄膜炎による意識障害と著しい白血球増多を呈した.播種性血管内凝固症候群を合併しメシル酸ガベキサートの投与を受け,点滴漏れを起こした右下腿部に皮膚潰瘍が発生した.1年あまりの間に植皮術を含めて数回の手術を受けたが難治性であり,間歇性跛行を訴えたことから血流障害を疑われた.血管造影およびCT検査により,腹部限局型解離性大動脈瘤と右総腸骨動脈閉塞と診断され,手術目的に当院に入院した.腹部正中切開で手術を行い16×8mmのY型人工血管を用いて腎動脈下腹部大動脈から両総腸骨動脈を置換した.手術後は良好に経過し,4週目に退院した.腎動脈下腹部限局型解離性大動脈瘤の手術適応については,通常の腹部大動脈瘤と同様と考える.

Stanford B型,DeBakey III b型急性大動脈解離に合併した上腸間膜動脈根部の動脈解離による腸管虚血に対し右外腸骨動脈-上腸間膜動脈バイパス術による上腸間膜動脈血行再建を行い救命しえた症例を経験したので報告する.症例は48歳,男性.Marfan症候群.10年前に大動脈基部置換術を受けた既往がある.突然の背部痛と腹痛で発症し造影CTでStanford B型急性大動脈解離に合併した上腸間膜動脈根部の動脈解離と診断された.大伏在静脈グラフトによる右外腸骨動脈-上腸間膜動脈バイパスを行い,さらに術後1年目に下行大動脈人工血管置換術を行った.グラフトは開存し,術後経過は良好である.

症例は72歳,男性.高血圧および甲状腺機能亢進症に対し加療中であった.左側腹部から下腹部にかけての激痛で発症した.発症から4日後の腹部CT検査で左水腎症と左総腸骨動脈瘤および動脈瘤による尿管の閉塞を認めた.左腎盂辺縁の不整像から左腎盂障害が疑われ,左総腸骨動脈瘤による尿管閉塞から急性左水腎症を発症したものと診断した.尿管に対する圧迫を解除する目的で左総腸骨動脈瘤人工血管置換術を行った.尿管剥離は行わなかった.術後尿路閉塞は解除され,良好に経過した.

症例は86歳,男性.肺結核,肺気腫,甲状腺機能低下症,胃癌に対し胃亜全摘術,直腸癌に対し直腸切断術の既往がある.洞機能不全症候群(徐脈頻脈症候群)に罹患し,右鎖骨下静脈穿刺によるDDDペースメーカー植え込み術を受けた.3ヵ月後,メチシリン耐性黄色ブドウ球菌によるペースメーカー感染を合併し,ペースメーカー摘出術と新規ペースメーカー植え込み術を行った.新規ペースメーカー植え込みに際しては,胸郭変形と人工肛門があり,全身状態不良なことから,局所麻酔下左第6肋骨床小切開アプローチによる心筋電極植え込み術を実施した.手術後は感染の再発もなく良好に経過した.通常,この方法は全身麻酔下に行われているが,本例のような特殊な例では局所麻酔下による植え込みも可能であり,経静脈的心内膜電極挿入が困難な場合には選択肢の一つとなりうる.

We theoretically investigate how deformation of an 1 s type exciton wavefunction affects four-wave-mixing signals near 1 s -exciton resonance in a semiconductor quantum well. For this we derive boson-boson interaction and boson-photon nonlinear coupling with the exciton-bosonization method, by taking into account the deformation of excitons.

We derive a bosonized Hamiltonian for a semiconductor quantum well with a light field by a new bosonization method taking exactly into account the composite-particle effects of excitons. Then we apply the bosonized Hamiltonian to the four-wave-mixing (FWM) processes. The obtained Hamiltonian describes two-boson states corresponding to bound and unbound two-exciton states and guarantees exclusion of unphysical states, which cannot exist in the fermionic space due to the Pauli exclusion principle. Calculated results of the FWM signals are in good agreement with the experimental ones, and therefore, the bosonized Hamiltonian turns out to be able to describe two-exciton correlations effectively.

We propose an exact bosonization scheme for two two-fermion composites with identical internal structures, that is, a mapping of the two-exciton (four-fermion) subspace to a two-boson subspace. We obtain analytical, exact expressions of the boson-boson interactions and the boson-photon ones taking into full account that the commutation relation of the composite bosons deviates from the ideal-boson commutation due to internal motions of the composite. We can distinguish the "composite-particle effects' from the Coulomb interactions among the fermions in the interactions. With this method, origins of optical nonlinearity in a system with two 1s excitons are studied in terms of the mutual excitonic correlations and exciton-photon interactions.

A 74-year-old woman with exertional angina was diagnosed with occlusion of the left coronary ostium associated with a rudimentary aortic valve cusp. A transesophageal echocardiogram, a multi-detector computed tomographic scan, and a coronary angiographic scan revealed the rudimentary aortic cusp covering the small left coronary aortic sinus leading to occlusion of the ostium of the left coronary artery, despite the intact coronary arteries. After excision of the rudimentary left coronary cusp, the left coronary ostium appeared intact. An aortic valve replacement with annular enlargement using a bioprosthetic valve was performed. The patient uneventfully recovered without angina.

Using a high-affinity phosphate transporter gene of Arabidopsis thaliana, PHT1, as a probe, three Arabidopsis homologs were isolated, named PHT4, PHT5 and PHT6, in addition to the previously isolated PHT2 and PHT3. The amino acid sequences deduced from the three nucleotides were 32-42% homologous with microbial phosphate transporters of Saccharomyces cerevisiae (PHO84), Neurospora crassa (PHO-5) and Glomus versiforme (GvPT). PHT1, PHT2, PHT3 and PHT6 were clustered in a 25-kbp region of chromosome V. PHT1 and PHT4 transcripts were detected in roots. Interestingly, suspension-cultured cells expressed only PHT4. PHT4 and PHT5 located within a genetic distance of 6.4 cM on chromosome II, and were close to a phosphate accumulation mutant pho2. Genomic sequencing revealed no difference in the sequences of the two genes in both pho2 and wild-type. The PHT4 transcript was expressed at similar levels in the mutant and wild-type. These results demonstrate that neither PHT4 nor PHT5 is allelic to PHO2.

A higher plant homologue to the high-affinity phosphate transporter gene of yeast ( Saccharomyces cerevisiae ) PHO84 was isolated from Arabidopsis thaliana . Expression of the Arabidopsis gene PHT1 at high levels in tobacco-cultured cells increased the rate of phosphate uptake. The uptake activity attributable to the transgene was inhibited by protonophores, suggesting an H + cotransport mechanism of phosphate uptake, and had a K m of 3.1 μM which is within limits characteristic of high-affinity transport mechanisms. These results indicate that PHT1 encodes a high-affinity phosphate transporter. The transgenic cells exhibited increased biomass production when the supply of phosphate was limited, establishing gene engineering of phosphate transport as one approach toward enhancing plant cell growth.

A 76-year-old man, who had been treated for an abdominal aortic aneurysm by endovascular aneurysm treatment at the age of 74, was admitted to our hospital with severe back pain. An emergent spiral computed tomographic (CT) scan revealed Stanford type B acute aortic dissection. His blood pressure was 164/108 mm Hg. Intravenous administration of nicardipine hydrochloride reduced it to 138/86 mm Hg, but he began to complain of numbness and sensory loss in his lower body although motor function was not disturbed. His femoral arterial pulse disappeared, and his lower body skin became pale, cold, and cyanotic. An immediate second CT scan revealed the squashed body of the abdominal aortic stent graft (Figs 1A, 2A). Reestablishment of the lower body circulation was necessary. During the preparation for surgery, we elevated his systolic blood pressure to greater than 150 mm Hg to increase the collateral blood flow to the lower body. Ten minutes later, his lower body blood flow was reestablished spontaneously. A third CT scan revealed the reopening of the stent graft

I型CD36欠損症患者では,妊娠や輸血によりCD36(Naka)に感作されることで抗CD36抗体(anti-Naka)を産生し,その後の輸血にさいし血小板輸血不応答や輸血後紫斑病を惹起する.症例は72歳,女性.妊娠歴,輸血歴ともになし.65歳時より高血圧症と心不全に対し内科的加療を受けてきた.この間,123I-β-methyl-iodophenyl pentadecanoic acid (BMIPP)心筋シンチグラムで無集積であったことを契機にI型CD36欠損症と診断された.72歳時,左下肢急性動脈閉塞を発症し左外腸骨動脈血栓摘除術と左外腸骨動脈-左浅大腿動脈バイパス術を無輸血で行った.そのさい心室瘤と冠状動脈狭窄を指摘され,待機的に心室瘤切除術と大動脈-冠状動脈バイパス術を行った.手術にさいし,CD36抗原への感作を回避する目的で貯血による自己血輸血と術中自己血回収を併用して他家血輸血を回避した.自己血輸血は輸血による合併症を回避する目的に行われるが,I型CD36欠損症もそのよい適応であると考える.

This study describes the effect of starch-synthesizing enzymes on biosynthesis of storage starch in rice amylose-extender mutants, which contain branched D-glucans with abnormal structures. Western blot analysis indicated that two out of five amylose-extender mutant lines lacked an isoform of starch branching enzyme, termed RBE3, although the levels of granule-bound starch synthase and a major form of branching enzyme, RBE1, were normal in these two mutants. Proteins corresponding to the 87-kDa RBE3 molecule were present in the three other amylose-extender mutants as well as in the wild type. However, the level of branching enzyme activity significantly decreased in all amylose-extender mutants, suggesting that the 87-kDa proteins in these three mutants are inactive forms of RBE3. Therefore, we conclude that formation of the abnormal branched glucans in the amylose-extender mutant of rice is due to the lack of the RBE3 activity. The cDNA clones encoding RBE3 have been identified from a normal rice seed cDNA library in lambda gt11, using a synthetic oligonucleotide as a probe. The deduced amino acid sequence of RBE3 indicates that this protein is initially synthesized as a precursor of 825 amino acids, including a 65-residue transit peptide at the NH2 terminus. The sequences of the catalytic regions in amylolytic enzymes are highly conserved in the sequence of RBE3. Thus, the branching enzyme isoform belongs to a family of the amylolytic enzymes. RBE3 also shares a noticeable degree of sequence identity with RBE1, especially at the central portion of the protein molecule. However, RBE3 possesses an approximately 70-residue extra sequence at the NH2 terminus and lacks a COOH-terminal sequence of almost 50 residues as compared with RBE1. The structural differences at both termini may explain the distinct role in starch synthesis for RBE1 and RBE3.

Molecular events associated with the evolution of an enzyme for C4 photosynthesis were investigated. In maize, at least three isozymes of phosphoenolpyruvate carboxylase [EC 4.1.1.31] are known: the C4-form, the C2-form and the root-form, being named according to their physiological roles and pattern of tissue distribution [Ting, I.P. & Osmond, C.B. (1973) Plant Physiol. 51, 448-453]. A cDNA clone which presumably encodes the C3-form isozyme was newly isolated and analyzed. Comparison of the sequences of the C3-form and C4-form isozymes revealed that (i) the homologies in the nucleotide and deduced amino acid sequences were 71 and 77%, respectively, and (ii) the gene for the C4-form isozyme evolved under strong G/C pressure. The genes for these isozymes were found to be located apart on different chromosomes. A phylogenetic tree was constructed using 8 amino acid sequences of phosphoenolpyruvate carboxylases from various sources. The topology of the tree indicated that, at least in monocots such as maize and sorghum, the genes for the C4-form and C3-form isozymes diverged from their common ancestral gene earlier than the monocot-dicot divergence (about 2 x 10(8) yr ago), though the divergence of maize (C4 plant) from wheat (C3 plant) is supposed to have occurred much later (6 x 10(7) yr ago).

We derive the effective Hamiltonian for the third-order nonlinear optical responses under 1s exciton resonance in semiconductor quantum wells with the use of new bosonization method, which takes exactly quasibosonic features of excitons into account. This Hamiltonian also includes the angular-momentum degrees of freedom of the elementary excitations and the photons. Momentum dependence of the boson–boson interactions and the boson–photon ones is exactly given.

症例は63歳の女性.左胸部痛と発熱を主訴として本院内科を受診し膿胸の診断にて入院した.膿胸は胸腔ドレーン留置による洗浄療法で寛解したが, 各種画像診断にて肝外側区域の肝内結石症による胆道感染から左膿胸に発展したものであると診断した.自験例における肝内結石症を病型分類で示すと [IE・L・S2l-m・D2lm], Sp0となりさらに外側区域の萎縮を認めたので治療として肝外側区域切除を選択した.自験例は胆道感染としては興味ある経過をとった症例でありまた治療については肝切除のよい適応であった.

During a period of 1969-88, 30 patients (14 males and 16-females) with primary varicose veins suffered from incurable leg ulcer were operated on in our institution. The average duration lasting lower extremity symptoms was 9.8 years in males or 10 years in females. While the average duration suffered from incurable leg ulcer was 14.6 months in males or 5.5 months in females. Solitary leg ulcers were seen in 23 cases and multiple ulcers in 7. Small ulcers measuring less than 2cm in diameter were completely cured by extensive whole saphenous vein stripping and excision of varices. For larger ulcers extrafascial or subfascial ligation of perforator branches with valve incompetence were performed. Furthermore, middle layer skin grafting was necessary for extensive ulcers measuring more than 3cm in diameter. Among 30 patients 9 needed skin grafting, and we have no experience of recurrence of treated ulcers. Thus incurable leg ulcer could be healed completely by operation within the average of 2.3 months.

We report a new surgical correction technique using an autologous atrial septal flap and anterolateral right atrial wall in a 3-year-old girl with partial anomalous pulmonary venous return and lower margin atrial septal defect. The patient recovered smoothly and is doing well 3 years after the operation.

Bacterial infection is a serious complication of permanent pacemaker implantation. A 52-year-old woman with sick sinus syndrome and vasospastic angina developed pacemaker infection 4 years after implantation, with methicillin-resistant Staphylococcus aureus detected in arterial blood cultures. We treated the septicemia with antibiotics and removed the infected pacemaker. We treated sick sinus syndrome with intravenous nitroglycerin followed by oral maintenance isosorbide mononitrate. After cardiac pacing was discontinued following removal of the infected permanent pacemaker, the patient remained well, until her sudden death 3.5 years later. Although the precise cause of death was not clear, we suspected sick sinus syndrome or vasospastic angina, and now consider the outcome may have been more favorable if we had reimplanted a permanent pacemaker before she died.

Atresia in the aortic arch is a rare and severe congenital cardiovascular anomaly. Without surgical therapy, only a few patients can survive to adulthood. A 29-year-old woman with atresia of the aortic arch (Celoria-Patton Type A) without any intracardiac shunt underwent primary surgical correction involving reconstruction of the aortic arch with prosthetic interposition between the transverse aortic arch and the descending aorta and division of the persistent ductus arteriosus. Her postoperative course was uneventful, and she is now doing well at three years to date after surgical treatment.

A gene encoding a calcium-dependent seed-specific protein kinase (SPK) is abundantly expressed in developing rice seeds (Kawasaki, T et al. Gene (1993) 129, 183-189). Rice genomic clones encoding SPK were isolated using the entire cDNA fragment as a probe. Physical mapping of these genomic clones indicated that the genomic region corresponding to the entire cDNA was divided into two different regions, SPK-A and SPK-B, located on different rice chromosomes. The results of RACE-PCR analyses showed that the respective transcripts from SPK-A and SPK-B contained additional sequences which were not found in the SPK cDNA, and that these sequences were removed like introns during maturation of the SPK mRNA. These results suggest that two different RNAs were independently transcribed from SPK-A and SPK-B and joined, possibly by trans-splicing.

The recessive floury-2 (flo-2) locus of rice (Oryza sativa L.), which is located on chromosome 4, causes a strong reduction in expression of the gene encoding an isoform of branching enzyme RBE1 in immature seeds 10 d after flowering. Mapping of the RBE1 gene demonstrated the localization on rice chromosome 6, suggesting that the wild-type Floury-2 (Flo-2) gene regulates RBE1 gene expression in trans. However, reduced expression of the genes encoding some other starch-synthesizing enzymes, including another isoform of branching enzyme RBE3 and granule-bound starch synthase, was also found in the flo-2 seeds. In spite of the low level of RBE1 gene expression in the immature seeds of the flo-2 mutants, the RBE1 gene was equally expressed in the leaves of the wild type and flo-2 mutants. Thus, these results imply that the Flo-2 gene may co-regulate expression of some of the genes participating in starch synthesis possibly in a developing seed-specific manner.

The Brassica napus genome contains more than four phosphoenolpyruvate carboxylase (PEPCase) genes. Although the nucleotide sequences of these genes highly resemble each other, an intron corresponding to the 7th intron in the maize gene is present in PE15- and PE105-PEPCase genes but absent in PE3-PEPCase. The intron corresponding to the maize 3rd intron is absent in PE15- and PE105-PEPCase genes. Deletion of these introns occurred precisely such that the coding sequence is faithfully preserved with respect to the maize gene. The PE19-PEPCase gene contains a deletion in the 8th exon instead of the presence of those introns.

In C4 plants the activity of phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) is regulated by phosphorylation/dephosphorylation which is mediated by light/dark signals. The study using protein kinase inhibitors showed that the inhibition pattern of maize PEPC-protein kinase (PEPC-PK) is similar to that of myosin light chain kinase, a Ca2+-calmodulin-dependent PK. The kinase activity was also inhibited by EGTA and the inhibition was relieved by Ca2+. These results suggest that PEPC-PK is Ca2+-dependent in contrast with previous observations by other research groups.