Resistance of bioincised wood treated with wood preservatives to blue-stain and wood-decay fungi

Bioincising is a biotechnological process that aims at the improvement of wood preservative uptake in wood species with a low permeability, such as Norway spruce (Picea abies (L.) Karst). The process is based on a short-term pre-treatment with white-rot fungus Physisporinus vitreus. During incubation the membranes of bordered and half bordered pits are supposed to be degraded by fungal activity resulting in a better treatability of the wood structure for wood preservatives. In the present study, first of all the resistance of bioincised Norway spruce heartwood and untreated controls against blue-stain and wood-decay fungi (white- and brown-rot) was determined. Then, bioincised and untreated specimens were dipped or vacuum impregnated with six wood preservatives and substance uptake was assessed gravimetrically. Additionally, the penetration of 3-iodo-2-propynyl butylcarbamate (IPBC) into the wood was analyzed by high-pressure liquid chromatography (HPLC). Finally, wood resistance was assessed according to the European standards EN 152 and EN 113. Results showed no difference between bioincised wood without preservatives and the untreated wood against blue-stain discolouration. However, a significant (P < 0.05) increase in susceptibility against wood decay was recorded. In the bioincised wood samples a significantly higher uptake of all the different preservatives was determined and the HPLC-method revealed that IPBC penetrated deeper into bioincised wood than into control samples. The improved uptake of preservatives into bioincised wood resulted in a significantly higher resistance against white- and brown-rot fungi. However, only a slight protection against wood discolouration by blue-stain fungi was recorded. The results of this study show for the first time that the biotechnological process with P. vitreus can be used to improve wood durability by increasing the uptake and penetration of wood preservatives.     

Ratio of erythro and threo forms of beta-O-4 structures in tension wood lignin

The ratio of erythro and threo forms of beta-O-4 structures in tension wood lignin was investigated by ozonation analysis of wood meal taken from various positions in the stem of yellow poplar (Liriodendron tulipifera). The proportion of the erythro form was higher in tension wood than in opposite wood, and the methoxyl group content showed a similar trend. The proportion of the erythro form and the methoxyl group content in the 7 positions in the stem lignin was correlated (correlation coefficient R=0.98), suggesting that the type of aromatic ring, syringyl or guaiacyl, is one of the factors which stereochemically controls the ratio of erythro and threo forms of beta-O-4 structures during lignin formation.     

Comparative study on the delignification of Azadirachta indica (L) Del., wood by Chrysosporium asperatum and Trichoderma harzianum

Structural alterations induced in response to degradation by two white rot Basidiomycetes on the secondary xylem of Azadirachta indica (L) Del., was compared. In vitro decay test was employed to investigate the pattern of delignification of Azadirachta wood by Trichoderma harzianum and Chrysosporium asperatum. Wood samples inoculated with both the strains were analyzed for different periods viz. 30, 60, 90 and 120 days after fungal inoculation. Initially there was no appreciable percent weight loss of the wood blocks but later on (after 60 days) it increased rapidly and was found similar for both the strains (43-46% of wood mass). Samples inoculated with both the strains showed dual pattern of degradation i.e. selective delignification in the initial stage followed by simultaneous rot during advance stage of decay. Separation of the cells due to dissolution of middle lamella was the characteristic feature of both strains but in the advanced stage of decay, formation of erosion troughs were conspicuous in all the cell types. Other features such as cell wall thinning, rounded pit erosion, formation of erosion channels and bore holes were also observed frequently. Initially, fungal invasion started through the vessel lumen, followed by all the cell types of the xylem. From the vessels, mycelia entered into the adjacent rays and parenchyma cells through the pits. In advanced stage, degradation was so pronounced that rays were partially or even completely destroyed while many cells including vessels were either deformed or destroyed due to loss of rigidity of their walls. Structural alterations induced in response to C. asperatum and T. harzianum attack is described in details.     

A molecular approach to explore the extent of the threatened fungus Hypocreopsis rhododendri within wood

Hypocreopsis rhododendri is a rare fungus that grows on woody stems in hyperoceanic climax scrub on the west coasts of Britain, Ireland, and France. Knowledge of the distribution and abundance of the fungus is based entirely on sporocarp records; it does not account for any occurrence as vegetative mycelia. To address this issue, a H. rhododendri-specific polymerase chain reaction (PCR) was developed and used to assay Corylus avellana (hazel) stems for the presence of H. rhododendri mycelia. The primers ITSHrF and ITSHrR were designed within the internal transcribed spacer 2 region, and their specificity to H. rhododendri was established by their failure to amplify DNA extracted from 14 other Hypocreaceae species. The sensitivity of the assay was demonstrated by amplifying DNA extracted from 4 mg C. avellana wood spiked with 0.0013 % H. rhododendri mycelium. Samples of wood and bark were then taken from around and directly underneath 11 H. rhododendri sporocarps and assayed for the presence of H. rhododendri. PCR products were obtained from a third of the surface bark samples, but only one faint product was obtained from 70 samples taken from beneath the outer bark. The results support the view that H. rhododendri does not form mycelia within stems. We suggest that H. rhododendri is not a saprotrophic fungus, but instead appears to be a parasitic on the wood decay fungus Hymenochaete corrugata, with which it always occurs. Evidence that tissue of H. corrugata is present within the sporocarps of H. rhododendri is discussed.     

Seasonal dynamics of entomopathogenic nematodes of the genera Steinernema and Heterorhabditis as a response to abiotic factors and abundance of insect hosts

The seasonal dynamics of entomopathogenic nematodes (EPNs) of the genus Steinernema and Heterorhabditis were studied during one season in meadow and oak wood habitats, in the vicinity of Ceské Budejovice, Czech Republic. The influences of soil temperature, moisture, and abundance of suitable hosts on EPN dynamics were investigated. The host range of these nematodes, in both habitats was also observed. A total of four EPN species were found in both habitats. Steinernema affine was the dominant species both in oak wood and in meadow. Additionally, the oak wood habitat was inhabited by S. kraussei and S. weiseri; the meadow habitat by Heterorhabditis bacteriophora. The mean abundance of total EPN community was 28,000ind./m(2) in oak wood and 11,000ind./m(2) in meadow. The seasonal dynamics of entomopathogenic nematodes in both habitats were characterized by high nematode densities in the beginning of the season, followed by a rapid decrease, and then stabilization. EPN abundances did not show any apparent correlation with soil temperature and moisture, but they were negatively correlated with the abundance of suitable insect hosts. Inter- and intraspecific competition for limited nutrients (hosts) probably played a major role in EPN seasonal dynamics. Broad host range of entomopathogenic nematodes in both habitats was predominantly represented by dipteran and coleopteran larvae. Most common hosts belonged to the families Asilidae, Bibionidae, and Empididae (Diptera), as well as Carabidae and Curculionidae (Coleoptera).     

White-rots, chlorine and the environment - a tale of many twists

White-rot fungi possess a unique oxidative mechanism by which the recalcitrant lignin component of wood is mineralised. The activity of lignin-degrading enzymes, chiefly lignin and manganese peroxidases, depends on several small organic molecules. Some of these (e.g. chloroanisyl alcohols) are chloroaromatics and may act as environmental pollutants in the forest soil, whereas the synthesis of others (e.g. veratryl alcohol) requires chloromethane. Certain white-rot genera, notably Phellinus and Inonotus, release excess quantities of chloromethane into the atmosphere where it acts as a greenhouse gas. On the other hand, their powerful ligninolytic system enables white-rot fungi to degrade a wide range of man-made environmental pollutants, including recalcitrant chloroaromatics such as DDT, PCP, 2,4-D and 2,4,5-T. This review describes the multifarious interactions of white-rot fungi with their environment via the chlorine cycle.     

New xylological data and the biogeography of the Iberian Peninsula during the Early Cretaceous

The position of the Iberian Peninsula during the Early Cretaceous, sandwiched between Laurasia and Gondwana, makes it an important area for the biogeography study of terrestrial ecosystems. Relevant data are, however, scarce. The discovery of silicified wood in the west of the Cameros Basin, in the village Hacinas (Spain), is the first record of the genus Protopodocarpoxylon in Spain and the seventh of Agathoxylon. A new species, Protopodocarpoxylon haciniensis sp. nov., is described. The anatomy of the samples studied shows that paleoclimatic conditions during the Early Cretaceous in the western part of the Cameros Basin were favorable to tree growth, with good water supply during the growth season. Although much impoverished in comparison with Western Europe, the Iberian Early Cretaceous wood floras are clearly Laurasian in affinity.     

A new species of Phaeohelotium from Nothofagus forests in Argentina and Chile, with a key to the Southern Hemisphere species

Phaeohelotium nothofagi, sp.nov., found on fallen wood and leaves of Nothofagus dombeyi, is described and illustrated. The fungus is characterized by pale yellow discs, and fumose ascospores with asperulate walls. A key with distributional data for the five species of the genus now known in the Southern Hemisphere is provided.     

A pilot study on lignocelluloses to ethanol and fish feed using NMMO pretreatment and cultivation with zygomycetes in an air-lift reactor

A complete process for the production of bioethanol and fungal biomass from spruce and birch was investigated. The process included milling, pretreatment with N-methylmorpholine-N-oxide (NMMO), washing of the pretreated wood, enzymatic hydrolysis, and cultivation of the zygomycetes fungi Mucor indicus. Investigated factors included wood chip size (0.5-16 mm), pretreatment time (1-5 h), and scale of the process from bench-scale to 2 m high air-lift reactor. Best hydrolysis yields were achieved from wood chips below 2 mm after 5 h of pretreatment. Ethanol yields (mg/g wood) of 195 and 128 for spruce, and 175 and 136 for birch were achieved from bench-scale and airlift, respectively. Fungal biomass yields (mg/g wood) of 103 and 70 for spruce, and 86 and 66 for birch from bench scale and airlift respectively were simultaneously achieved. NMMO pretreatment and cultivation with M. indicus appear to be a good alternative for ethanol production from birch and spruce.     

三种外来入侵斑潜蝇种间竞争研究进展

美洲斑潜蝇、南美斑潜蝇、三叶斑潜蝇是危害蔬菜、花卉的世界性大害虫。不同种间相互更替或取代的现象时有发生。根据国内外相关研究报道,综述了对近年来3种斑潜蝇种间竞争的研究。对斑潜蝇种间更替和取代现象的分析显示,生殖干扰、新生物型的出现、天敌、生态位、寄主植物以及抗药性等因素可能是影响它们种间竞争的关键。以期为斑潜蝇种群演替研究及防治策略制定提供参考。     

Intermolecular interactions of homologs of germ plasm components in mammalian germ cells

In some species such as flies, worms, frogs and fish, the key to forming and maintaining early germ cell populations is the assembly of germ plasm, microscopically distinct egg cytoplasm that is rich in RNAs, RNA-binding proteins and ribosomes. Cells which inherit germ plasm are destined for the germ cell lineage. In contrast, in mammals, germ cells are formed and maintained later in development as a result of inductive signaling from one embryonic cell type to another. Research advances, using complementary approaches, including identification of key signaling factors that act during the initial stages of germ cell development, differentiation of germ cells in vitro from mouse and human embryonic stem cells and the demonstration that homologs of germ plasm components are conserved in mammals, have shed light on key elements in the early development of mammalian germ cells. Here, we use FRET (Fluorescence Resonance Energy Transfer) to demonstrate that living mammalian germ cells possess specific RNA/protein complexes that contain germ plasm homologs, beginning in the earliest stages of development examined. Moreover, we demonstrate that, although both human and mouse germ cells and embryonic stem cells express the same proteins, germ cell-specific protein/protein interactions distinguish germ cells from precursor embryonic stem cells in vitro; interactions also determine sub-cellular localization of complex components. Finally, we suggest that assembly of similar protein complexes may be central to differentiation of diverse cell lineages and provide useful diagnostic tools for isolation of specific cell types from the assorted types differentiated from embryonic stem cells.     

Comparison based on field tests of three low-environmental-impact wood treatments

In order to promote the use of Pinus pinea L. wood within the Migliarino-San Rossore Nature Reserve (Pisa, central Italy), three low-environmental-impact wood treatments, supposed to enhance natural durability, were compared. Impregnations with an oil-based preservative and natural waxes and a wood thermal treatment were tested in the field in accordance with standards ENV 12037 and EN 252. The above-ground test revealed that: P. pinea sapwood is more durable than Pinus sylvestris sapwood; all the alternative treatments showed a low mean decay level; wax and oil treatments performed as well as the traditional copper-based preservative; the natural durability class of P. pinea will only be calculated upon the complete failure of all reference lap-joints. The main outcomes from the in-ground test were: All the tested treatments increased the durability of wood, and the protective effectiveness of alternative treatments was comparable to traditional copper-based ones, or even superior in the case of heated oil. Taking certain mechanical and aesthetic limitations into account, all the treatments were suitable for the promotion of the P. pinea wood commodity in use classes 3 and 4.     

Phenolic and heterocyclic metabolite profiles of the grapevine pathogen Eutypa lata

The ascomycete Eutypa lata is the causative agent of eutypa dieback in grapevines, a serious economic problem in major wine grape producing areas. In order to develop a predictive, non-destructive assay for early detection of fungal infection, the phenolic metabolite profiles of 11 strains of E. lata grown on four different artificial growth media were analyzed by HPLC and their variability compared with growth on Cabernet Sauvignon grapevine wood and wood extracts. Six compounds were generally produced in significant amounts, namely eutypinol, eulatachromene, and eutypine and its benzofuran cyclization product, together with siccayne and eulatinol. The two most widely distributed and abundant metabolites were eutypinol and eulatachromene, which were present in 8 of the strains grown on grapewood aqueous extract fortified with sucrose. Metabolite production on grapevine extract was greatly enhanced relative to the artificial media, indicating that this native substrate provides optimal conditions and a more representative profile of the metabolites produced in the natural disease state. The primary metabolites were tested in a grapeleaf disc bioassay to establish their relative toxicity. Neither eutypinol nor siccayne were phytotoxic; eulatachromene, eulatinol, eutypine, and the benzofuran exhibited necrotic effects in the bioassay. The results indicate that eutypa dieback may be caused by several E. lata metabolites rather than a single compound.     

Anatomy and lignin distribution in reaction phloem fibres of several Japanese hardwoods

Background and Aims Although tension wood formation and the structure of gelatinous fibres (G-fibres) have been widely investigated, studies of the influence of the reaction phenomenon on phloem fibres have been few and incomplete in comparison with those of xylem wood fibres. This study was undertaken to clarify the influence of stem inclination on phloem fibres using several Japanese hardwood species that produce different G-fibre types in tension wood. Methods Eight hardwood species were inclined at 30-45° at the beginning of April. Specimens were collected in July and December. The cell-wall structure and lignin distribution of phloem fibres on both the tension and opposite sides were compared by light microscopy, ultraviolet microscopy, confocal laser scanning microscopy after staining with acriflavine, and transmission electron microscopy after staining with potassium permanganate. Key Results Three types of changes were found in tension-side phloem fibres: (1) increases in the proportion of the syringyl unit in lignin in the S(1) and S(2) layers and compound middle lamella (Cercidiphyllum japonicum), (2) formation of unlignified gelatinous layers (Melia azedarach and Acer rufinerve) and (3) increases in the number of layers (n) in the multi-layered structure of S(1) + S(2) + n (G + L) (Mallotus japonicus). Other species showed no obvious change in cell-wall structure or lignin distribution. Conclusions Phloem fibres of the tree species examined in our study showed three types of changes in lignin distribution and cell-wall structure. The reaction phenomenon may vary with tree species and may not be closely related to G-fibre type in tension wood.     

Sex in flies: what 'body--mind' dichotomy?

Sexual behavior in Drosophila results from interactions of multiple neural and genetic pathways. Male-specific fruitless (fruM) is a major component inducing male behaviors, but recent work indicates key roles for other sex-specific and sex-non-specific components. Notably, male-like courtship by retained (retn) mutant females reveals an intrinsic pathway for male behavior independent of fruM, while behavioral differences between males and females with equal levels of fruM expression indicate involvement of another sex-specific component. Indeed, sex-specific products of doublesex (dsxF and dsxM), that control sexual differentiation of the body, also contribute to sexual behavior and neural development of both sexes. In addition, the single product of the dissatisfaction (dsf) gene is needed for appropriate behavior in both sexes, implying additional complexities and levels of control. The genetic mechanisms controlling sexual behavior are similar to those controlling body sexual development, suggesting biological advantages of modifying an intermediate intrinsic pathway in generation of two substantially different behavioral or morphological states.     

脂肪酸对中华哲水蚤摄食两种海洋微藻的指示作用

在室内以饥饿培养为对照,以海洋原甲藻(Prorocentrum micans)和中肋骨条藻(Skeletonema costatum)培养中华哲水蚤(Calanus sinicus),研究了各脂肪酸标记对中华哲水蚤摄食不同饵料的指示作用。结果显示,海洋原甲藻中18 ∶ 4ω3、22 ∶ 6ω3含量较高,中肋骨条藻中16 ∶ 1ω7、20 ∶ 5ω3的含量较高。二者分别表现出典型的甲藻门和硅藻门的脂肪酸组成特征。中华哲水蚤的脂肪酸组成有两个特点:(1)20 ∶ 5ω3和22 ∶ 6ω3的含量均较高;(2)其体内表征桡足类浮游植物食性、由桡足类自身合成的20 ∶ 1和22 ∶ 1脂肪酸占有相当的比例。虽然中华哲水蚤对不同脂肪酸的吸收和转化效率不同,但以脂肪酸作为标记还是成功的指示了中华哲水蚤对微藻的摄食。在饥饿培养中,首先消耗的是那些浮游动物自身不能合成的多不饱和脂肪酸,而结构脂肪酸都表现出了较高的保守性。结合各脂肪酸标记变化趋势和Pearson相关性分析的结果认为,18 ∶ 4ω3、18 ∶ 4ω3/16 ∶ 1ω7、∑18/∑16能较好的指示中华哲水蚤对海洋原甲藻的摄食,仅16 ∶ 1ω7/18 ∶ 4ω3能指示中华哲水蚤对中肋骨条藻的摄食。     

Marker genes identify three somatic cell types in the fetal mouse ovary

The two main functions of the ovary are the production of oocytes, which allows the continuation of the species, and secretion of female sex hormones, which control many aspects of female development and physiology. Normal development of the ovaries during embryogenesis is critical for their function and the health of the individual in later life. Although the adult ovary has been investigated in great detail, we are only starting to understand the cellular and molecular biology of early ovarian development. Here we show that the adult stem cell marker Lgr5 is expressed in the cortical region of the fetal ovary and this expression is mutually exclusive to FOXL2. Strikingly, a third somatic cell population can be identified, marked by the expression of NR2F2, which is expressed in LGR5- and FOXL2 double-negative ovarian somatic cells. Together, these three marker genes label distinct ovarian somatic cell types. Using lineage tracing in mice, we show that Lgr5-positive cells give rise to adult cortical granulosa cells, which form the follicles of the definitive reserve. Moreover, LGR5 is required for correct timing of germ cell differentiation as evidenced by a delay of entry into meiosis in Lgr5 loss-of-function mutants, demonstrating a key role for LGR5 in the differentiation of pre-granulosa cells, which ensure the differentiation of oogonia, the formation of the definitive follicle reserve, and long-term female fertility.     

Lignification in relation to the biennial growth habit in brassicas

The forage brassicas are a useful model system for the study of wood formation because the thickened cell walls of their vascular tissue can vary widely in lignin content. Solid-state 13C NMR spectroscopy was used to quantify lignin, and determine features of its structure, in the vascular cell walls of forage rape (Brassica napus L.), and Thousandhead and marrowstem cultivars of kale (Brassica oleracea L. var. acephala). During the first season of vegetative growth, lignin levels in these cell walls remained low in the upper part of the stems despite the physical resemblance of this tissue to wood. The extended flowering stems produced in the following year were thinner and their vascular tissue contained much more strongly lignified cell walls. The structure of the lignin was typical of angiosperm wood. It showed only small variations in syringyl/guaiacyl ratio, but this ratio increased with lignin content and thus with the proportion of the lignin that was associated with secondary cell-wall layers.