Identification of the CAD gene from Eucalyptus urophylla GLU4 and its functional analysis in transgenic tobacco

Cinnamyl alcohol dehydrogenase (CAD) catalyzes the final step in lignin biosynthesis. The genus Eucalyptus belongs to the family Myrtaceae, which is the main cultivated species in China. Eucalyptus urophylla GLU4 (GLU4) is widely grown in Guangxi. It is preferred for pulping because of its excellent cellulose content and fiber length. Based on GLU4 and CAD gene expression, a Eucalyptus variety low in lignin content should be obtained using transgenic technology, which could reduce the cost of pulp and improve the pulping rate, and have favorable prospects for application. However, the role and function of CAD in GLU4 is still unclear. In the present study, EuCAD was cloned from GLU4 and identified using bioinformatic tools. Subsequently, in order to evaluate its impact on lignin synthesis, a full-length EuCAD RNAi vector was constructed, and transgenic tobacco was obtained via Agrobacterium-mediated transformation. A significant decrease in CAD expression and lignin content in transgenic tobacco demonstrated a key role for EuCAD in lignin biosynthesis and established a regulatory role for RNAi. In our study, the direct molecular basis of EuCAD expression was determined, and the potential regulatory effects of this RNAi vector on lignin biosynthesis in E. urophylla GLU4 were demonstrated. Our results provide a theoretical basis for the study of lignin biosynthesis in Eucalyptus.

[Clinicopathologic analysis of extranodal Rosai-Dorfman disease of breast: a report of 12 cases]

OBJECTIVE

To investigate the clinicopathologic features, diagnosis and differential diagnosis of extranodal Rosai-Dorfman disease(RDD)of the breast.

METHODS

Twelve cases of extranodal RDD of the breast were analyzed using hematoxylin-eosin stain and immunohistochemical staining.The morphological features and immunophenotype were observed by light microscopy, accompanied with a review of the literature.

RESULTS

Twelve cases of extranodal RDD of the breast are presented. The patients were women and their ages ranged from 15 to 55 years (mean =37 years). Except one patient with involvement of the right breast and ipsilateral axillary lymph nodes, other eleven patients' disease confined to the breast. Seven cases located in the right breast, the other five cases in the left breast. Microscopically, it showed a typical morphology, characterized by diffuse infiltration of large histiocytes, lymphocytes and plasmocytes that formed irregular nodular structure with light and dark appearance under microscope. Spindling of histiocytosis often arranged in a vague storiform with prominent fibrosis, accumulation of foamy histiocytes and scattered atypical nuclei. The characteristic histocytes and emperipolesis could not be seen obviously in extranodal RDD of the breast.Immunohistochemical staining showed histocytes were strongly positive for S-100 protein, CD68 and CD163, while negative for CD1a.

CONCLUSIONS

Extranodal RDD of the breast is very rare. Because of unconspicuous emperipolesis and lack of specificity in clinic and images, extranodal RDD of the breast is easy to be misdiagnosed as other histiocytosis. The microscopic differential diagnosis includes idiopathic granulomatous mastitis, infective granulomas, langerhans cell histiocytosis, IgG4 related sclerosing disease, Erdheim-Chester disease, benign fibrous histiocytoma, malignant fibrous histiocytoma and Hodgkin Lymphoma. Light and dark appearance under microscope is the important clue in diagnosis of extranodal RDD in breast. Immunohistochemistry is also helpful.

Chimeric repressor of PtSND2 severely affects wood formation in transgenic Populus

NAC domain transcription factors are important regulators that activate the secondary wall biosynthesis in wood formation. In this work, we investigated the possible functions of an NAC family member SECONDARY WALL-ASSOCIATED NAC DOMAIN PROTEIN2 (PtSND2) using chimeric repressor silencing technology. Reverse transcription-polymerase chain reaction, subcellular localization and transcriptional activation analyses indicated that PtSND2 is a wood-associated transcriptional factor with the predicted transcriptional activation activity, which could be inhibited by the repression domain SUPERMAN REPRESSION DOMAIN X (SRDX) in yeast. Wood formation was severely repressed in transgenic poplar plants overexpressing PtSND2-SRDX. Meanwhile, the secondary cell wall thickness of xylem fibers was restrained, and the contents of cellulose and lignin were obviously decreased in the stems of transgenic plants. Further studies indicated that expressions of a number of wood-associated genes were down-regulated in the stems of transgenic plants. Our results suggest that PtSND2 may play important roles during the secondary growth of stems in poplar.

Surface morphology and defect formation of the {100} face of ZnCd(SCN)4crystals investigated by AFM

Surface morphology and defect formation of the prismatic {100} face of ZCTC crystals were investigated by atomic force microscopy (AFM). Both screw-dislocation-controlled growth and two-dimensional nucleation growth occur on the face at a supersaturation of 0.03. Steps advance with strong kinetic anisotropy along theb-axis direction, probably because different parts of the ZCTC molecules are exposed along different crystallographic directions. By comparing heights of elementary steps with the structure of the ZCTC crystal, it is deduced that the growth of ZCTC crystals occurs mostly by direct incorporation of monomers or dimers of ZCTC molecules into the crystal. Defects of hollow channels, negative crystals and cracks that are oriented preferentially along the direction of theborcaxis were observed. The formation of the defects is mainly related to the growth mechanism and structural features of the ZCTC crystal.

Effects of laminin glycopeptides on metastasis-related behaviors of cancer cells

Our previous reports have shown that laminin-glycopeptides (LN-GPs), the total glycopeptides prepared from laminin (LN), can prevent the experimental lung metastasis and liver metastasis of mouse cancer cells. In order to explore the anti-metastatic mechanism of LN-GPs, we studied the effects of LN-GPs on metastasis-related behaviors of cancer cells in vitro. LN-GPs did not affect cell survival. However, LN-GPs inhibited cell attachment and spreading of S180 cells on LN- and Matrigel-substrate in dose-dependent and time-dependent manners. Moreover, inhibition of cell attachment and spreading on Matrigel substrates were much greater on Matrigel substrate than on LN substrate. In the presence of LN-GPs, S180 cells on LN substrate changed from a flattened polygonal shape to a round one, the migration of S180 cells on LN substrate decreased, and the number of a highly invasive human pulmonary giant carcinoma PG cells invading Matrigel filter in a Boyden chamber was reduced. LN-GPs thus have multiple inhibitory effects on cancer metastasis-related behaviors.

A novel bifunctional fusion enzyme catalyzing ethylene synthesis via 1-aminocyclopropane1-carboxylic acid

A C terminus truncated soybean 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (466 aa) was fused to an N terminus truncated tomato ACC oxidase (312 aa) to create a 778-amino acid fusion polypeptide. This ACC synthase-ACC oxidase fusion enzyme (ACSO) was expressed in a heterologous prokaryotic Escherichia coli system, which is capable of converting endogenous S-adenosyl-L-methionine (AdoMet) to ethylene. The molecular weight of the fusion enzyme, ACSO, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was 90 +/- 3 kDa. Gel filtration analysis indicates that the native ACSO is oligomeric and is capable of converting exogenously supplied AdoMet to ethylene. The ethylene production rate of ACSO fusion enzyme was determined to be 6.0 nmol h-1 mg-1 under our assaying conditions using the partially purified enzyme extract. In the enzyme reaction mixture, an increase in ethylene production catalyzed by the bifunctional ACSO was accompanied by a decrease in ACC accumulation. Similarly, in E. coli cells, the level of ACC, produced as an intermediate during the sequential reactions from AdoMet to ethylene, was also found to arise earlier than that of ethylene. Because ACSO could produce ethylene from the ubiquitous AdoMet in living cell and the method commonly used to measure gaseous ethylene is simple, fast, and sensitive, we anticipate this bifunctional fusion enzyme to be useful as a reporter and for research in molecular biology, developmental biology, fermentation, and genetic engineering.

First- and second-year aboveground growth and productivity of two Populus hybrids grown at ambient and elevated CO(2)

Two hybrid poplar (Populus) clones (the fast-growing clone Beaupré (P. trichocarpa Torr. and Gray x P. deltoides Bartr. ex Marsh.) and the slow-growing clone Robusta (P. deltoides Bartr. ex Marsh. x P. nigra L.)) were grown from hardwood cuttings for one or two growing seasons (1993-1994) in either ambient or elevated (= ambient + 350 micro mol mol(-1)) CO(2) in open-top chambers at the University of Antwerpen. Both clones responded positively to the elevated CO(2) treatment with increased stem volume and aboveground biomass production; however, the clones exhibited different response strategies to the elevated CO(2) treatment, and the responses varied with cutting age and duration of exposure. Clone Beaupré responded to the elevated CO(2) treatment with increases in leaf area and leaf area index during both the first and second growing seasons, but little increase in height growth. Clone Robusta exhibited increased height growth, leaf biomass and total leaf nitrogen content in response to elevated CO(2), but no increase in leaf area index. The elevated CO(2) treatment increased the total number of branches and total branch biomass in both clones during both growing seasons. At the end of the first growing season, woody stem biomass of the fast- and slow-growing clones was increased by 38 and 55%, respectively. At the end of the second growing season, stem volume was increased by 43% in clone Beaupré and by 58% in clone Robusta. The increase in stem volume was a result of the stimulation of both height and diameter growth in the slow-growing clone, whereas only height growth was stimulated in the fast-growing clone. In the fall of the first growing season, the average date of bud set in clone Robusta was advanced by 4 days in the elevated CO(2) treatment; there were no other significant effects of the elevated CO(2) treatment on bud set. The elevated CO(2) treatment enhanced leaf C/N ratios in both clones in both years.

Effects of CO2 enrichment, leaf position and clone on stomatal index and epidermal cell density in poplar (Populus)

The effects of CO₂ , enrichment and leaf position on stomatal characteristics (stomatal density, stomatal index and stomatal pore length) and epidermal cell density were examined for two different Populus clones, Beaupre and Robusta, grown from cuttings in open-top chambers under ambient and elevated atmospheric CO₂ conditions. Both clones had amphistomatous leaves, and stomatal density was significantly larger on the abaxial leaf surface than on the adaxial. Significant interactions between CO₂ enrichment, leaf position and clone were observed for most stomatal and epidermal characteristics. A significant reduction of the number of stomata mm^-2 under elevated CO₂ was observed in expanding leaves near the upper portion of the plant for both leaf surface sides and in both clones. For the abaxial leaf side only, this reduction under elevated CO₂ , was accompanied by a similar reduction of the stomatal index in both clones. In mature leaves on the middle and lower portion of the plants, there was no significant effect of the CO₂ treatment on stomatal density. In young, expanding leaves near the upper part of the plant there were significant interactions between the CO₂ treatment and leaf surface side for epidermal cell density. The latter increased under elevated CO₂ at the abaxial leaf surface, but decreased at the adaxial surface on the upper part of the plant. Total epidermal cell numbers of mature, fully expanded leaves increased under elevated CO₂ , in both clones. The observation that interactions with leaf age and/or leaf position significantly confound the CO₂ , treatment effect on stomatal and epidermal cell densities, might contribute to the elucidation of the problem of the phenomenon of stomatal density reduction under elevated atmospheric CO₂ .