The influence of a reduced gibberellin biosynthesis and nitrogen supply on the morphology and anatomy of leaves and roots of tomato (Solanum lycopersicum)

We investigated how the differences in growth and morphology, between fast-growing wildtype (Wt) tomato ( Solanum lycopersicum L.) plants and slow-growing gibberellin (GA) deficient W335 mutants, were reflected in cell numbers and cell sizes. We also studied whether the differences between the Wt and the low-GA mutant would persist at a growth-limiting supply of nitrate. Both a low endogenous GA concentration and a low supply of nitrate reduced the number and size of leaf cells, whereas they increased the size and number of root cortex cells. The effects of low N-supply on the size and number of leaf and root cells did not depend on endogenous GA concentrations. The mutant's higher allocation to roots seemed to be the result of the strongly reduced growth of the shoot.     

Effects of age and distance on the composition of mixed deciduous forest fragments in an agricultural landscape

Abstract. Forest patches in central Belgium were inventoried twice for the presence or absence of forest plant species to study the effects of age and distance on species composition. All forests in the study area were subdivided based on their land use history. To avoid effects of autocorrelated environmental characteristics on species composition, habitat homogeneity was indirectly investigated using a TWINSPAN classification of the vegetation data. Two major habitats (alluvial and non‐alluvial forests) were distinguished and analysed separately. Patterns of species composition were investigated at the landscape level using Mantel tests. Species composition similarity measures were calculated between all pairs of fragments based on the floristic data. A highly significant correlation was found between species composition similarity and inter‐patch distance. Difference in age, which we used as a measure for habitat quality, was less important in explaining species composition patterns. The effects of spatial configuration became significant when difference in age was accounted for, and a partial correlation was calculated between inter‐patch distance and species composition similarity. Different results were found for alluvial and non‐alluvial forest types. Alluvial forests were more influenced by the spatial configuration than the non‐alluvial. For the non‐alluvial forest type effects measured with the difference in age between forest fragments obscured the effects of inter‐patch distance. Based on our findings we suggest that species composition is not only internally generated, but external processes such as differential colonization caused by varying degrees of isolation may be of overriding importance.     

Renewable resources in the chemical industry – Breaking away from oil?

Rising prices for fossil-based raw materials suggest that sooner or later renewable raw materials will, in principle, become economically viable. This paper examines this widespread paradigm. Price linkages like those seen for decades particularly in connection with petrochemical raw materials are now increasingly affecting renewable raw materials. The main driving force is the competing utilisation as an energy source because both fossil-based and renewable raw materials are used primarily for heat, electrical power and mobility. As a result, prices are determined by energy utilisation. Simple observations show how prices for renewable carbon sources are becoming linked to the crude oil price. Whether the application calls for sugar, starch, virgin oils or lignocellulose, the price for the raw material rises with the oil price. Consequently, expectations regarding price trends for fossil-based energy sources can also be utilised for the valuation of alternative processes. However, this seriously calls into question the assumption that a rising crude oil price will favour the economic viability of alternative products and processes based on renewable raw materials. Conversely, it follows that these products and processes must demonstrate economic viability today. Especially in connection with new approaches in white biotechnology, it is evident that, under realistic assumptions, particularly in terms of achievable yields and the optimisation potential of the underlying processes, the route to utilisation is economically viable. This makes the paradigm mentioned at the outset at least very questionable.     

An extracellular loop of the human non-gastric H,K-ATPase alpha-subunit is involved in apical plasma membrane polarization.

The human non-gastric H,K-ATPase, ATP1AL1, belongs to the gene family of P-type ATPases. Consistent with their physiological roles in ion transport, members of this group, including the Na,KATPase and the gastric and non-gastric H,K-ATPases, are differentially polarized to either the basolateral or apical plasma membrane in epithelial cells. However, their polarized distribution is highly complex and depends on specific sorting signals or motifs which are recognized by the subcellular targeting machinery. For the gastric H,K-ATPase it has been suggested that the 4(th) transmembrane spanning domain (TM4) and its flanking regions induce conformational sorting motifs which direct the ion pump exclusively to the epithelial apical membrane. Here, we show in transfected Madin-Darby canine kidney (MDCK) cells that the related non-gastric H,KATPase, ATP1AL1, does contain similar sorting motifs in close proximity to TM4. A short extracellular loop between TM3 and TM4 is critical for this pump's apical delivery. A single point mutation in the corresponding region redirects ATP1AL1 to the basolateral membrane. In conclusion, our work provides further evidence that the cellular distribution of P-type ATPases is determined by conformational sorting motifs.     

Phosphorus nutrition and mycorrhiza effects on grass leaf growth. P status- and size-mediated effects on growth zone kinematics

This study tested whether leaf elongation rate (LER, mm h(-1)) and its components--average relative elemental growth rate (REGRavg, mm mm(-1) h(-1)) and leaf growth zone length (L(LGZ), mm)--are related to phosphorus (P) concentration in the growth zone (P(LGZ) mg P g(-1) tissue water) of Lolium perenne L. cv. Condesa and whether such relationships are modified by the arbuscular mycorrhizal fungus (AMF) Glomus hoi. Mycorrhizal and non-mycorrhizal plants were grown at a range of P supply rates and analysed at either the same plant age or the same tiller size (defined by the length of the sheath of the youngest fully expanded leaf). Both improved P supply (up to 95%) and AMF (up to 21%) strongly increased LER. In tillers of even-aged plants, this was due to increased REGRavg and L(LGZ). In even-sized tillers, it was exclusively due to increased REGRavg. REGRavg was strictly related to P(LGZ) (r2 = 0.95) and independent of tiller size. Conversely, L(LGZ) strictly depended on tiller size (r2 = 0.88) and not on P(LGZ). Hence, P status affected leaf growth directly only through effects on relative tissue expansion rates. Symbiosis with AMF did not modify these relationships. Thus, no evidence for P status-independent effects of AMF on LER was found.     

Porcine circovirus 2 uses heparan sulfate and chondroitin sulfate B glycosaminoglycans as receptors for its attachment to host cells

Monocyte/macrophage lineage cells are target cells in vivo for porcine circovirus 2 (PCV2) replication. The porcine monocytic cell line 3D4/31 supports PCV2 replication in vitro, and attachment and internalization kinetics of PCV2 have been established in these cells. However, PCV2 receptors remain unknown. Glycosaminoglycans (GAG) are used by several viruses as receptors. The present study examined the role of GAG in attachment and infection of PCV2. Heparin, heparan sulfate (HS), chondroitin sulfate B (CS-B), but not CS-A, and keratan sulfate reduced PCV2 infection when these GAG were incubated with PCV2 prior to and during inoculation of 3D4/31 cells. Enzymatic removal of HS and CS-B prior to PCV2 inoculation of 3D4/31 cells significantly reduced PCV2 infection. Similarly, when PCV2 virus-like particles (VLP) were allowed to bind onto 3D4/31 cells in the presence of heparin and CS-B, attachment was strongly reduced. Titration of field isolates and low- and high-passage laboratory strains of PCV2 in the presence of heparin significantly reduced PCV2 titers, showing that the capacity of PCV2 to bind GAG was not acquired during in vitro cultivation but is an intrinsic feature of wild-type virus. When Chinese hamster ovary (CHO) cells were inoculated with PCV2, relative percentages of PCV2-infected cells were 27% +/- 8% for HS-deficient and 12% +/- 10% for GAG-deficient cells compared to wild-type cells (100%). Furthermore, it was shown using heparin-Sepharose chromatography that both PCV2 and PCV2 VLP directly interacted with heparin. Together, these results show that HS and CS-B are attachment receptors for PCV2.     

Structure-toxicity relationships for different types of dinuclear platinum complexes

Nine structurally distinct dinuclear platinum complexes have been evaluated in a novel model system for the investigation of renal epithelial toxicity of platinum drugs. The results showed that these compounds are toxic when applied at the basolateral side of renal epithelia, whereas their toxic effects on the apical side are negligible. Such a difference in toxicity of the complexes has been found to result from their poor uptake through the apical membrane, as compared to the basolateral membrane. Toxicity of the compounds on the basolateral side varies depending on their structure. Structure-toxicity relationships for the group of complexes with rigid ligands and for the group of complexes with flexible ligands are discussed. Among the dinuclear complexes with rigid ligands, sterically hindered complexes are less toxic, due to their poor uptake and low reactivity towards glutathione. Within the group of complexes with flexible ligands, cis-configured isomers are more toxic than their trans-counterparts.     

Solution structures and model membrane interactions of lactoferrampin, an antimicrobial peptide derived from bovine lactoferrin

Bovine lactoferrampin (LFampinB) has been identified as a novel antimicrobial peptide, which is derived from the N-terminal lobe of bovine lactoferrin. In this study, the solution structure of LFampinB bound to negatively charged sodium dodecyl sulphate micelles and zwitterionic dodecyl phosphocholine micelles was determined using 2-dimensional nuclear magnetic resonance (NMR) spectroscopy. The interaction between LFampinB and multilamellar phospholipid vesicles, containing choline and glycerol head groups, was examined using differential scanning calorimetry (DSC). In addition, the interaction between the N-terminal tryptophan residue and model membranes of varying composition was analyzed by fluorescence spectroscopy. LFampinB adopts an amphipathic alpha-helical conformation across the first 11 residues of the peptide but remains relatively unstructured at the C-terminus. The hydrophobic surface of the amphipathic helix is bordered by the side chains of Trp1 and Phe11, and is seen in both micelle-bound structures. The fluorescence results suggest that Trp1 inserts into the membrane at the lipid/water interface. The phenyl side chain of Phe11 is oriented in the same direction as the indole ring of Trp1, allowing these two residues to serve as anchors for the lipid bilayer. The DSC results also indicate that LFampinB interacts with glycerol head groups in multilamellar vesicles but has little effect on acyl chain packing. Our results support a two step model of antimicrobial activity where the initial attraction of LFampinB is mediated by the cluster of positive charges on the C-terminus followed by the formation of the N-terminal helix which binds to the surface of the bacterial lipid bilayer.     

Shallow-soil endemics: adaptive advantages and constraints of a specialized root-system morphology

Worldwide, many rare plant species occur in shallow-soil, drought-prone environments. For most of these species, the adaptations required to be successful in their own habitats, as well as their possible consequences for establishment and persistence in others, are unknown. Here, two rare Hakea (Proteaceae) species confined to shallow-soil communities in mediterranean-climate south-western Australia were compared with four congeners commonly occurring on deeper soils. Seedlings were grown for 7 months in a glasshouse in individual 1.8 x 0.2-m containers, to allow for unconstrained root development. In addition, a reciprocal transplant experiment was carried out. The rare Hakea species differed consistently from their common congeners in their spatial root placement. They invested more in deep roots and explored the bottom of the containers much more quickly. In the reciprocal transplant experiment they showed increased survival in their own habitat, but not in others. This research suggests that shallow-soil endemics have a specialized root system that allows them to explore a large rock surface area, thereby presumably increasing their chance to locate cracks in the underlying rock. However, this root-system morphology may be maladaptive on deeper soils, providing a possible explanation for the restricted distribution of many shallow-soil endemics.     

The effect of patients' sex on physicians' recommendations for total knee arthroplasty

Background

The underuse of total joint arthroplasty in appropriate candidates is more than 3 times greater among women than among men. When surveyed, physicians report that the patient''s sex has no effect on their decision-making; however, what occurs in clinical practice may be different. The purpose of our study was to determine whether patients'' sex affects physicians'' decisions to refer a patient for, or to perform, total knee arthroplasty.

Methods

Seventy-one physicians (38 family physicians and 33 orthopedic surgeons) in Ontario performed blinded assessments of 2 standardized patients (1 man and 1 woman) with moderate knee osteoarthritis who differed only by sex. The standardized patients recorded the physicians'' final recommendations about total knee arthroplasty. Four surgeons did not consent to the inclusion of their data. After detecting an overall main effect, we tested for an interaction with physician type (family physician v. orthopedic surgeon). We used a binary logistic regression analysis with a generalized estimating equation approach to assess the effect of patients'' sex on physicians'' recommendations for total knee arthroplasty.

Results

In total, 42% of physicians recommended total knee arthroplasty to the male but not the female standardized patient, and 8% of physicians recommended total knee arthroplasty to the female but not the male standardized patient (odds ratio [OR] 4.2, 95% confidence interval [CI] 2.4–7.3, p < 0.001; risk ratio [RR] 2.1, 95% CI 1.5–2.8, p < 0.001). The odds of an orthopedic surgeon recommending total knee arthroplasty to a male patient was 22 times (95% CI 6.4–76.0, p < 0.001) that for a female patient. The odds of a family physician recommending total knee arthroplasty to a male patient was 2 times (95% CI 1.04–4.71, p = 0.04) that for a female patient.

Interpretation

Physicians were more likely to recommend total knee arthroplasty to a male patient than to a female patient, suggesting that gender bias may contribute to the sex-based disparity in the rates of use of total knee arthroplasty.Disparity in the use of medical or surgical interventions based on patient characteristics, such as sex, ethnic background or socioeconomic status, is an important health care issue.¹ Women are less likely than men to receive lipid-lowering medication after a myocardial infarction,² receive kidney dialysis,³ be admitted to an intensive care unit,⁴ or undergo cardiac catheterization,⁵ renal transplantation⁶ or total joint arthroplasty.⁷ Although women''s preferences for surgery or the information needed to make an informed decision may differ from men and explain sex-based differences in care,^8,9 subtle or overt gender bias may inappropriately influence physicians'' clinical decision-making.^2,5,7 A more pronounced gender bias might be expected when the clinical decision involves an elective surgical procedure such as total joint arthroplasty.Total hip and knee arthroplasty is the definitive treatment for relieving pain and restoring function in people with moderate to severe osteoarthritis for whom medical therapy has failed.¹⁰ Although age-adjusted rates of total joint arthroplasty are higher among women than among men,¹¹ based on a population-based epidemiologic survey, underuse of arthroplasty is 3 times greater in women.⁷ In prior opinion surveys, more than 93% of referring physicians and orthopedic surgeons have reported that patients'' sex has no effect on their decision to refer a patient for, or perform, total knee arthroplasty.^12,13 However, there may be a difference between what is reported in a survey and what occurs in clinical practice. The purpose of our study was to determine whether physicians would provide the same recommendation about total knee arthroplasty to a male and a female standardized patient presenting to their offices with identical clinical scenarios that differed only by sex.