Stimulating the production of homoisoflavonoids in cell suspension cultures of Caesalpinia pulcherrima using cork tissue

It has previously been demonstrated that cork tissue increases the efficiency of the production of lipophilic secondary metabolites in diverse plant cell suspension cultures. In the present study, three new homoisoflavonoids--named dihydrobonducellin, 2'-methoxydihydrobonducellin, and 2'-methoxybonducellin--and bonducellin and isobonducellin were isolated from Caesalpinia pulcherrima cultured cells coincubated with cork tissue. Cork tissue increased the production of 2'-methoxybonducellin by about 7-fold relative to control cells, and more than 80% of the product was recoverable from the cork tissue. When cork tissue and methyl jasmonate or yeast extract were added simultaneously to the medium, the amount of 2'-methoxybonducellin produced increased further. The production of the other four homoisoflavonoids was enhanced by variable amounts. Our results indicate that the addition of cork tissue would be an effective technique for investigating formation of secondary metabolites that usually accumulate only in trace amounts.     

Atomic force microscopy of pea starch granules: granule architecture of wild-type parent, r and rb single mutants, and the rrb double mutant

AFM studies have been made of the internal structure of pea starch granules. The data obtained provides support for the blocklet model of starch granule structure (Carbohydr. Polym. 32 (1997) 177-191). The granules consist of hard blocklets dispersed in a softer matrix material. High-resolution images have yielded new insights into the detailed structure of growth rings within the granules. The blocklet structure is continuous throughout the granule and the growth rings originate from localised defects in blocklet production distributed around the surface of spheroidal shells within the granules. A mutation at the rb locus did not lead to significant changes in granule architecture. However, a mutation at the r locus led to loss of growth rings and changed blocklet structure. For this mutant the blocklets were distributed within a harder matrix material. This novel composite arrangement was used to explain why the granules had internal fissures and also changes in gelatinisation behaviour. It is suggested that the matrix material is the amylose component of the granule and that both amylose and amylopectin are present within the r mutant starch granules in a partially-crystalline form. Intermediate changes in granule architecture have been observed for the double mutant rrb.     

Suction pressure can induce uncoupling of the plasma membrane from cortical actin

We tested the hypothesis that a pressure difference can cause blebbing associated with uncoupling of the plasma membrane from the cortical actin, a phenomenon found earlier in locomoting blebbing Walker carcinosarcoma cells. Untreated, initially spherical Walker carcinosarcoma cells were exposed to suction pressure by partial aspiration into micropipettes. The suction pressure required to induce blebbing was in the range of 0.9-3 cm H2O, i.e., somewhat lower than the increase in intracellular pressure measured before formation of protrusions in Amoeba proteus (Yanai et al., Cell Motil. Cytoskeleton 33, 22-29, 1996). The response was temperature-dependent, blebbing occurring more frequently at 37 degrees C than at room temperature. Blebbing was associated with formation of cytoplasmic actin layers, restriction rings and/or of gaps in the plasma membrane-associated cortical actin. The results support the view that blebbing associated with uncoupling of cortical actin and plasma membrane as observed in locomoting cells can be caused by a pressure gradient.     

Intersex and Littorina littorea in Cork Harbour: results of a medium-term monitoring programme

Cork Harbour, located on the south coast of Ireland, is a complex, multi-user environment. In the present study Littorina littorea (L.) is used as a bio-indicator of TBT pollution, as it has a wide range within the harbour, unlike the more common bio-indicator, Nucella lapillus (L.), which is limited to rocky substrata near the mouth of the harbour. Intersex in L. littorea is used for the first time in Ireland as a medium-term indicator of TBT pollution and results show that there are no deviations in levels of intersex over the three year period from 1994–1996. These results are discussed.     

Ring formation on otoliths and scales of Pagrus pagrus: a comparative study

One annulus formed on the scales of farmed red porgy Pagrus pagrus each year during March and one opaque zone on the otoliths during June. Scales proved to be more sensitive than otoliths in recording the life history of the red porgy. A false annulus (ring of capture) was observed on the scales of the 0+ age group, but not on the otoliths. A gradual lengthening of the period of annulus formation was observed, from the younger to the older fish. The annulus formation in fish older than 2+ was less synchronized, due to the aquaculture conditions. Scales were more accurate than otoliths in annuli formation. A high percentage of missing or additional opaque zones were observed on otoliths of older fish. These irregularities were related to fish maturation and/or farming conditions. Farmed fish grew three times as fast as the wild fish.     

Stand structure of the emergent conifer Araucaria laubenfelsii) in maquis and rainforest,Mont Do,New Caledonia

Abstract Despite its small size, New Caledonia has a flora which includes 43 endemic species of conifer. This study examines the stand structure of the New Caledonian conifer, Araucaria laubenfelsii Corbasson, a species which occurs on ukramafic soils as an emergent tree in rainforest and in an unusual structural association with maquis vegetation. Fire and cyclone blow-down are the primary disturbances in the maquis, but fire is infrequent in the rainforests which is evident from the low proportion of fire scarred trees. Preliminary results show abundant seedlings and saplings of A. laubenfelsii both in maquis and forest. Size class distributions of individuals suggest that the species is continuously regenerating in the maquis and immature forests. Variability in the stand structure in maquis communities reflects the probable patchy nature of disturbance from small-scale fires and blow-down from tropical cyclones. In mature forests, Nothofagus codonandra (Baillon) Steenis is the dominant canopy species and ‘other tree species’ are continuously regenerating, while the size class distributions and basal area of A. laubenfelsii suggest that there is, at present, limited regeneration of this species. Tree ring counts indicate that individuals in forest areas grow at a slower rate than those in maquis, but attain greater age, probably as a result of greater protection from fire.     

Volcanic explosive eruptions of the Vesuvio decrease tree-ring growth but not photosynthetic rates in the surrounding forests

Volcanic eruptions impact the global and the hemispheric climate, but it is still unknown how and to what degree they force the climate system and in particular the global carbon cycle. In this paper, the relationships between individual eruptions (reconstructed for the past using written records), tree primary productivity (estimated using ring widths), photosynthetic rate and stomatal conductance (assessed by carbon and oxygen isotope data) are investigated, to understand the impact of volcanic eruptions on net primary production. Data from a mixed stand of Fagus sylvatica L. and Acer pseudoplatanus L. located in the area of the Vesuvio volcanic complex (Southern Italy) showed a significant decrease in ring width following each eruption. Isotope analyses indicate a change in climatic conditions after such events. Specifically, the lower oxygen isotope ratio in the tree‐ring cellulose strongly suggests an increase in relative humidity and a decrease in temperature, with the latter resulting in a strong limitation to tree‐ring growth. The carbon isotope ratio was only moderately but not significantly reduced in the years of volcanic eruption, suggesting no major changes in C fixation rates. This work is a case study on the effects of volcanic eruptions resulting in strong climatic changes on the local scale. This is an opportunity to explore the process and causal relationships between climatic changes and the response of the vegetation. Thus, we propose here a realistic model scenario, from which we can extrapolate to global scales and improve our interpretations of results of global studies.     

Reconstruction of disturbance history of a typical broad-leaved Pinus koraiensis forest and mechanisms of disturbance occurrence

该文依托于小兴安岭典型阔叶红松(Pinus koraiensis)林9 hm2森林动态监测样地,对样地内林窗边缘主要树种红松和臭冷杉(Abies nephrolepis)进行生长释放判定分析,重建了冠层树木的干扰历史。结果表明:整体上林窗木与非林窗木的生长变化百分率变化规律基本一致,而不同林窗间生长变化百分率存在明显的差异,林窗干扰及其产生的影响存在较大的变异性。在1733–1738、1748–1752、1769–1771、1798–1801、1827–1833、1841–1844、1935–1939及1968–1973年间红松生长释放较强,其中1752、1770、1800、1830、1842、1937及1970年出现了明显的干扰峰;在1889–1904、1932–1938、1947–1973和1986–2005年间臭冷杉生长释放较强,其中1894、1934、1951、1968和1990年出现了明显的干扰峰。红松干扰存在2.0 a、3.5 a、3.8 a、7.3–7.9 a和9.1–18.2 a的显著周期,臭冷杉干扰存在3.5–3.6 a、7.5–48.8 a和65–85 a的显著周期。风干扰是典型阔叶红松林干扰释放的主要因子,异常温度也影响该地区树木生长释放事件。太阳活动通过影响局地风速、温度、降水等气候因子以及其他大尺度气候模态影响林窗动态,可能是小兴安岭典型阔叶红松林的干扰机制之一。     

Vasodilator effects of peptides derived from egg white proteins

The aim of this work was to investigate the effect of several peptides, identified before and after simulated gastrointestinal digestion of an egg white hydrolysate, on the vascular function, in rat aorta. The sequences IVF, RADHPFL and YAEERYPIL (0.1 mM) induced vasodilatation in intact aortic rings, with the maximum percentage of dilation corresponding to RADHPFL (40.5 ± 7.0%). Two of the end products of the gastrointestinal digestion, RADHP and YPI, also showed vasodilator activity with degrees of relaxation higher than 50%. However, all these peptides failed to induce relaxation in endothelium-denuded aortic rings. The relaxation induced by RADHP was concentration-dependent and it was partially blocked by the nitric oxide synthase inhibitor l-NAME (100 μM) and by the B₁ bradykinin receptor antagonist Des-HOE 140 (30 nM), thus showing that it was mediated by NO production through the activation of B₁ bradykinin receptors. These findings suggest that these peptides could reduce the vascular resistance and could be used as functional food ingredients in the prevention and treatment of hypertension.     

Acorn dispersal estimated by radio-tracking

Bird-dispersed seeds are difficult to track, especially in the case of long-distance dispersal events. To estimate the oak dispersal distance and the seed shadow generated by the European jay (Garrulus glandarius), we inserted radio-transmitters in 239 acorns, placed them in bird-feeders and then located them by radio-tracking. Using this methodology we located the exact caching site of 94 Quercus ilex and 54 Q. suber acorns and determined the caching habitat characteristics (vegetation type, distance, spatial distribution). The results show that: (1) there is no differences in the dispersal distance distribution between the different acorn species or sizes, (2) dispersal distances range from approximately 3 m up to approximately 550 m (mean = 68.6 m; median = 49.2 m), (3) recently abandoned fields and forest tracks were the sites preferred by jays to cache acorns, whereas fields and shrublands were avoided and (4) seed shadows showed acorn aggregation zones (i.e. clusters of caches) close to the feeder as well as isolated caches at longer distances. The results also suggest that radio-transmitters are a cheap and reliable way to determine seed shadows and quantify both seed dispersal and post-dispersal seed predation for medium to large seeds.