Hair morphology and systematics ofPhysalis (Solanaceae)

Hair morphology was exammed on developing seedlings and mature plants of ten species from five of seven series inPhysalis. The taxonomic importance of hair development and the distribution of hair types then was evaluated with respect to other comparative data. Two classes of hair types were observed, as found in earlier investigations ofSolanum andRhododendron. The first hair class comprises a sequence from unbranched hairs to dendroid-stelliform hairs. Hairs of this class show considerable variability among taxa in size, presence or absence of glandular tips, and presence and degree of branching, and so were useful in making taxonomic comparisons. The second hair class consists of short hairs, each tipped with a multicellular gland. This second hair class was not useful taxonomically because of its lack of variability in morphology and its often rare occurrence on a plant. The taxa studied exhibit distinctive trichome features which serve to distinguish series and, in some cases together with other data, provided new insight into previously enigmatic species relationships.     

Hair morphology and the relationships of species inSolanum sect.Basarthrum

The usefulness of features of leaf hairs in distinguishing subgenera and sections is well documented in bothRhododendron andSolanum. In this analysis of the taxa ofSolanum sect.Basarthrum (23 species), and of a sample of closely related taxa from sect.Petota (22 species), it is shown that such features serve to delineate subsectional groups such as series and some species as well. SectionBasarthrum has an unexpected diversity of hair types. Although this group has been characterized by 2-celled bayonet hairs, more than one half of the taxa in the section bear multicellular finger hairs, and 3 species also possess branched hairs. Thus, major rearrangements of the species previously assigned to sect.Basarthrum are indicated or supported by pubescence features. The taxa studied from seriesEtuberosa andJuglandifolia (both of sect.Petota) show hair types that a) are relatively primitive for the section, and b) show linkage between sects.Petota andBasarthrum.     

Flavonoid data and populational observations in support of hybrid status for Populus acuminata

Flavonoid distribution and populational composition at the collection sites of several samples of Populus acuminata strongly suggest that this taxon is an inter-sectional hybrid between P. angustifolia, sect. Tacamahaca and any one of two or three different species of the section Aigeiros, when the entire range is considered. In the vicinity of the type locality, the Aigeiros parent is P. sargentii. Within any population, foliage of trees of P. acuminata is characterized by morphological intermediacy and an essentially additive flavonoid profile, as compared to the two parental taxa present. In habit the trees resemble those of P. sargentii, and habitats at the collection sites were found to be somewhat intermediate. Fifteen flavonoid compounds were consistently present in samples of the putative hybrid. Twelve of these had diagnostic value because they were absent in one of the parental species. One compound, apigenin 7-O-diglucoside, was found only in P. acuminata. In part, our identifications correspond to compounds reported by Crawford in a morphological and chemical study of P. acuminiata.     

Comparison of forest above‐ground biomass from dynamic global vegetation models with spatially explicit remotely sensed observation‐based estimates

Gaps in our current understanding and quantification of biomass carbon stocks, particularly in tropics, lead to large uncertainty in future projections of the terrestrial carbon balance. We use the recently published GlobBiomass data set of forest above‐ground biomass (AGB) density for the year 2010, obtained from multiple remote sensing and in situ observations at 100 m spatial resolution to evaluate AGB estimated by nine dynamic global vegetation models (DGVMs). The global total forest AGB of the nine DGVMs is 365 ± 66 Pg C, the spread corresponding to the standard deviation between models, compared to 275 Pg C with an uncertainty of ~13.5% from GlobBiomass. Model‐data discrepancy in total forest AGB can be attributed to their discrepancies in the AGB density and/or forest area. While DGVMs represent the global spatial gradients of AGB density reasonably well, they only have modest ability to reproduce the regional spatial gradients of AGB density at scales below 1000 km. The 95th percentile of AGB density (AGB₉₅) in tropics can be considered as the potential maximum of AGB density which can be reached for a given annual precipitation. GlobBiomass data show local deficits of AGB density compared to the AGB₉₅, particularly in transitional and/or wet regions in tropics. We hypothesize that local human disturbances cause more AGB density deficits from GlobBiomass than from DGVMs, which rarely represent human disturbances. We then analyse empirical relationships between AGB density deficits and forest cover changes, population density, burned areas and livestock density. Regression analysis indicated that more than 40% of the spatial variance of AGB density deficits in South America and Africa can be explained; in Southeast Asia, these factors explain only ~25%. This result suggests TRENDY v6 DGVMs tend to underestimate biomass loss from diverse and widespread anthropogenic disturbances, and as a result overestimate turnover time in AGB.     

Spatio-temporal dynamics of endophyte diversity in the canopy of European ash (Fraxinus excelsior)

Leaf-inhabiting endophytic fungi of Fraxinus excelsior growing in a floodplain forest were isolated during 2008 to investigate vertical community structure, species richness and seasonal variation. The analysis of 848 fungal endophytes from 213 leaves resulted in 50 different species. In the understorey, infection density and species richness were higher than in the crowns of mature trees throughout the whole vegetation period. Within tree crowns, sun-exposed leaves of the top canopy exhibited the lowest infection rates. Most species were rare or absent in spring and in the light crowns and frequent in autumn and the understorey. However, some species, especially the two most frequent, Alternaria infectoria and A. alternata, deviated from these patterns. Young leaves were nearly free of endophytes. Apparently, the subsequent infection and establishment of fungi strongly depend on microclimatic parameters and leaf characters, which create highly variable spatial and temporal colonisation patterns within an individual tree.     

Hooked on fat: the role of lipid synthesis in cancer metabolism and tumour development

An increased rate of lipid synthesis in cancerous tissues has long been recognised as an important aspect of the rewired metabolism of transformed cells. However, the contribution of lipids to cellular transformation, tumour development and tumour progression, as well as their potential role in facilitating the spread of cancerous cells to secondary sites, are not yet fully understood. In this article, we review the recent findings that support the importance of lipid synthesis and metabolism in tumorigenesis. Specifically, we explore the role of aberrant lipid biosynthesis in cancer cell migration and invasion, and in the induction of tumour angiogenesis. These processes are crucial for the dissemination of tumour cells and formation of metastases, which constitute the main cause of cancer mortality.     

On the correct use of ‘data’

Acknowledgement  Thanks are due to Drs. Paul Johnston (P.Johnston@ exeter.ac.uk) and E. William Beese (ebeese@t-online.de) for kindly providing dictionary definitions and for sharing their thoughts about the correct use of ‘data’.