Can the agricultural AquaCrop model simulate water use and yield of a poplar short‐rotation coppice?

We calibrated and evaluated the agricultural model AquaCrop for the simulation of water use and yield of a short‐rotation coppice (SRC) plantation with poplar (Populus) in East Flanders (Belgium) during the second and the third rotation (first 2 years only). Differences in crop development and growth during the course of the rotations were taken into account during the model calibration. Overall, the AquaCrop model showed good performance for the daily simulation of soil water content (R² of 0.57–0.85), of green canopy cover (R² > 0.87), of evapotranspiration (ET; R² > 0.76), and of potential yield. The simulated, total yearly water use of the SRC ranged between 55% and 85% of the water use of a reference grass ecosystem calculated under the same environmental conditions. Crop transpiration was between 67% and 93% of total ET, with lower percentages in the first than in the second year of each rotation. The observed (dry mass) yield ranged from 6.61 to 14.76 Mg ha^?1 yr^?1. A yield gap of around 30% was observed between the second and the third rotation, as well as between simulated and observed yield during the third rotation. This could possibly be explained by the expansion of the understory (weed) layer; the relative cover of understory weeds was 22% in the third year of the third rotation. The agricultural AquaCrop model simulated total water use and potential yield of the operational SRC in a reliable way. As the plantation was extensively managed, potential effects of irrigation and/or fertilization on ET and on yield were not considered in this study.     

A cyclic peptidylic inhibitor of murine urokinase-type plasminogen activator: changing species specificity by substitution of a single residue

The variance of the U-box domain in 64 Arabidopsis thaliana (thale cress) E3s (ubiquitin-protein ligases) was used to examine the interactions between E3s and E2s (ubiquitin-conjugating enzymes). E2s and E3s are components of the ubiquitin protein degradation pathway. Seven U-box proteins were analysed for their ability to ubiquitinate proteins in vitro in co-operation with different E2s. All U-box domains exhibited ubiquitination activity and interacted productively with UBC4/5-type E2s. Three and four of the U-box domains mediated ubiquitin addition in the presence of UBC13 and UBC7 E2s respectively, but no productive interaction was observed with the UBC15 E2 tested. The activity of AtPUB54 [Arabidopsis thaliana (thale cress) plant U-box 54 protein] was dependent on Trp(266) in the E2-binding cleft, and the E2 selectivity was changed by substitution of this position. The function of the distant U-box protein, AtPUB49, representing a large family of eukaryotic proteins containing a U-box linked to a cyclophilin-like peptidyl-prolyl cis-trans isomerase domain, was characterized biochemically. AtPUB49 functioned both as a prolyl isomerase and a chaperone by catalysing cis-trans isomerization of peptidyl-prolyl bonds and dissolving protein aggregates. In conclusion, both typical and atypical Arabidopsis U-box proteins were active E3s. The overlap in the E3/E2 selectivity suggests that in vivo specificity is not determined only by the E3-E2 interactions, but also by other parameters, e.g. co-existence or interactions with additional domains. The biochemical functions of AtPUB49 suggest that the protein can be involved in folding or degradation of protein substrates. Similar functions can also be retained within a protein complex with separate chaperone and U-box proteins.     

A Longitudinal Study of Disability,Cognition and Gray Matter Atrophy in Early Multiple Sclerosis Patients According to Evidence of Disease Activity

New treatment options may make “no evidence of disease activity” (NEDA: no relapses or disability progression and no new/enlarging MRI lesions, as opposed to “evidence of disease activity” (EDA) with at least one of the former), an achievable goal in relapsing-remitting multiple sclerosis (RRMS). The objective of the present study was to determine whether early RRMS patients with EDA at one-year follow-up had different disability, cognition, treatment and gray matter (GM) atrophy rates from NEDA patients and healthy controls (HC). RRMS patients (mean age 34 years, mean disease duration 2.2 years) were examined at baseline and one-year follow-up with neurological (n = 72), neuropsychological (n = 56) and structural MRI (n = 57) examinations. Matched HC (n = 61) were retested after three years. EDA was found in 46% of RRMS patients at follow-up. EDA patients used more first line and less second line disease modifying treatment than NEDA (p = 0.004). While the patients groups had similar disability levels at baseline, they differed in disability at follow-up (p = 0.010); EDA patients progressed (EDSS: 1.8–2.2, p = 0.010), while NEDA patients improved (EDSS: 2.0–1.7, p<0.001). Cognitive function was stable in both patient groups. Subcortical GM atrophy rates were higher in EDA patients than HC (p<0.001). These results support the relevance of NEDA as outcome in RRMS and indicate that pathological neurodegeneration in RRMS mainly occur in patients with evidence of disease activity.     

Matrix metalloproteinase-2 and -9 secretion by the equine ovary during follicular growth and prior to ovulation

Profound hormonally controlled tissue remodelling occurs in the equine ovary for follicle growth and development, and also for the alteration in follicle shape directed towards the ovulation fossa, the site where ovulation occurs. The aim of this study was to examine the spatial and temporal regulation of matrix metalloproteinases (MMP)-2 and MMP-9, important enzymes in tissue remodelling, during follicle growth, and ovulation. Using gelatin substrate zymography, we measured these MMPs in follicular fluid of large anovulatory follicles collected during spring transition, early dominant follicles (> 23 mm), and at oestrus in follicles approximately 3 days prior to ovulation, and post-hCG treatment when ovulation was predicted in approximately 4 h. The most abundant activity detected in follicular fluid was MMP-2, although there were no changes in secretion or activation in association with ovulation. The activity of MMP-9 was detected in lower amounts, with no changes prior to ovulation, although it decreased significantly (P < 0.05) post-hCG treatment. At oestrus, when different regions of the ovary were maintained in explant culture for 24 h, there were no significant changes in either MMP-2 or MMP-9 secretion by stromal tissues collected at the ovarian fossa, adjacent to the preovulatory follicle but away from the fossa, and a further site remote from the preovulatory follicle. Over this same time period, follicular progesterone (P < 0.01) and oestradiol (P < 0.05) increased significantly, although oestradiol tended to decrease after hCG administration. These findings indicate that MMP-2 and MMP-9 are not key acute regulators for the changes in follicle shape immediately prior to ovulation.     

FAS-Dependent Cell Death in α-Synuclein Transgenic Oligodendrocyte Models of Multiple System Atrophy

Multiple system atrophy is a parkinsonian neurodegenerative disorder. It is cytopathologically characterized by accumulation of the protein p25α in cell bodies of oligodendrocytes followed by accumulation of aggregated α-synuclein in so-called glial cytoplasmic inclusions. p25α is a stimulator of α-synuclein aggregation, and coexpression of α-synuclein and p25α in the oligodendroglial OLN-t40-AS cell line causes α-synuclein aggregate-dependent toxicity. In this study, we investigated whether the FAS system is involved in α-synuclein aggregate dependent degeneration in oligodendrocytes and may play a role in multiple system atrophy. Using rat oligodendroglial OLN-t40-AS cells we demonstrate that the cytotoxicity caused by coexpressing α-synuclein and p25α relies on stimulation of the death domain receptor FAS and caspase-8 activation. Using primary oligodendrocytes derived from PLP-α-synuclein transgenic mice we demonstrate that they exist in a sensitized state expressing pro-apoptotic FAS receptor, which makes them sensitive to FAS ligand-mediated apoptosis. Immunoblot analysis shows an increase in FAS in brain extracts from multiple system atrophy cases. Immunohistochemical analysis demonstrated enhanced FAS expression in multiple system atrophy brains notably in oligodendrocytes harboring the earliest stages of glial cytoplasmic inclusion formation. Oligodendroglial FAS expression is an early hallmark of oligodendroglial pathology in multiple system atrophy that mechanistically may be coupled to α-synuclein dependent degeneration and thus represent a potential target for protective intervention.     

Dynamic association of CD45 with detergent-insoluble microdomains in T lymphocytes

The receptor-like protein tyrosine phosphatase CD45 is essential for TCR signal transduction. Substrates of CD45 include the protein tyrosine kinases p56(lck) and p59(fyn), both of which have been shown to be enriched in detergent-insoluble microdomains. Here we find that there is a cholesterol-dependent association between CD45 and the raft-associated protein linker for activation of T cells, suggesting that CD45 and linker for activation of T cells may colocalize in lipid rafts. Consistent with this observation, we find that approximately 5% of total CD45 can be detected in Triton X-100-insoluble buoyant fractions of sucrose gradients, demonstrating that CD45 is not excluded from lipid rafts. Upon stimulation of T cells with anti-CD3, there is a reduction in the amount of CD45 found associating with lipid rafts. Our data suggest that CD45 is present in lipid rafts in T cells before activation, perhaps to activate raft-associated p56(lck), allowing membrane-proximal signaling events to proceed. Furthermore, the reduction in CD45 content of lipid rafts after CD3 stimulation may serve to limit the amounts of activated p56(lck) in rafts and thus possibly the duration of T cell responses.     

The HtrA Protease of Campylobacter jejuni Is Required for Heat and Oxygen Tolerance and for Optimal Interaction with Human Epithelial Cells

Campylobacter jejuni is a predominant cause of food-borne bacterial gastroenteritis in the developed world. We have investigated the importance of a homologue of the periplasmic HtrA protease in C. jejuni stress tolerance. A C. jejuni htrA mutant was constructed and compared to the parental strain, and we found that growth of the mutant was severely impaired both at 44°C and in the presence of the tRNA analogue puromycin. Under both conditions, the level of misfolded protein is known to increase, and we propose that the heat-sensitive phenotype of the htrA mutant is caused by an accumulation of misfolded protein in the periplasm. Interestingly, we observed that the level of the molecular chaperones DnaK and ClpB was increased in the htrA mutant, suggesting that accumulation of nonnative proteins in the periplasm induces the expression of cytoplasmic chaperones. While lack of HtrA reduces the oxygen tolerance of C. jejuni, the htrA mutant was not sensitive to compounds that increase the formation of oxygen radicals, such as paraquat, cumene hydroperoxide, and H₂O₂. Using tissue cultures of human epithelial cells (INT407), we found that the htrA mutant adhered to and invaded human epithelial cells with a decreased frequency compared to the wild-type strain. This defect may be a consequence of the observed altered morphology of the htrA mutant. Thus, our results suggest that in C. jejuni, HtrA is important for growth during stressful conditions and has an impact on virulence.     

Candicidin Biosynthesis Gene Cluster Is Widely Distributed among Streptomyces spp. Isolated from the Sediments and the Neuston Layer of the Trondheim Fjord,Norway

A large number of Streptomyces bacteria with antifungal activity isolated from samples collected in the Trondheim fjord (Norway) were found to produce polyene compounds. Investigation of polyene-containing extracts revealed that most of the isolates produced the same compound, which had an atomic mass and UV spectrum corresponding to those of candicidin D. The morphological diversity of these isolates prompted us to speculate about the involvement of a mobile genetic element in dissemination of the candicidin biosynthesis gene cluster (can). Eight candicidin-producing isolates were analyzed by performing a 16S rRNA gene-based taxonomic analysis, pulsed-field gel electrophoresis, PCR, and Southern blot hybridization with can-specific probes. These analyses revealed that most of the isolates were related, although they were morphologically diverse, and that all of them contained can genes. The majority of the isolates studied contained large plasmids, and two can-specific probes hybridized to a 250-kb plasmid in one isolate. Incubation of the latter isolate at a high temperature resulted in loss of the can genes and candicidin production, while mating of the “cured” strain with a plasmid-containing donor restored candicidin production. The latter result suggested that the 250-kb plasmid contains the complete can gene cluster and could be responsible for conjugative transfer of this cluster to other streptomycetes.Actinomycete bacteria, especially those belonging to the family Streptomycetaceae, are well-known producers of secondary metabolites with diverse biological activities. Representatives of the genus Streptomyces produce a variety of antibiotics with antibacterial, antifungal, and antitumor activities. The majority of antibiotic-producing streptomycetes have been isolated from terrestrial environments, while antibiotic-producing streptomycetes from the marine sources remain largely unexplored. Therefore, studies of streptomycetes from the marine environment are important for unraveling their potential for antibiotic production. In addition, such studies might reveal the means by which antibiotic biosynthesis and resistance genes are spread in nature.It is widely acknowledged that plasmids play an important role in genetic exchange between bacterial species. Conjugative plasmids are quite common in Streptomyces strains (13), and a number of these mobile genetic elements have been characterized in detail. The characterized mobile genetic elements include both circular plasmids, such as pIJ101 from Streptomyces lividans (14) and SCP2 from Streptomyces coelicolor (2, 35), and linear plasmids, such as SLP2 from S. lividans (6) and SCP1 from S. coelicolor (38, 39). The presence of a linear plasmid in Streptomyces was first reported in 1979, and the plasmid was the 17-kb pSLA2 plasmid of Streptomyces rochei (11). SCP1 of S. coelicolor was discovered in the early 1970s (38, 39), but because of its large size (356 kb), isolation of this plasmid with conventional techniques was not possible and therefore it was not recognized as a linear plasmid until pulsed-field gel electrophoresis (PFGE) was invented. Later, SCP1 was shown to harbor a complete set of genes for biosynthesis of the antibiotic methylenomycin (21; K. F. Chater, C. J. Bruton, S. J. O''Rouke, and A. W. Wietzorrek, 5 July 2001, Patent Cooperation Treaty international application WO/2001/048228), while another linear plasmid, found in S. rochei, has been shown to contain genes for biosynthesis of both lankamycin and lankacidin (16, 19, 28, 36). Other examples of plasmids include pPZG103 carrying oxytetracycline biosynthesis genes acquired from the chromosome of Streptomyces rimosus (10) and pKSL from Streptomyces lasaliensis, which might be involved in the production of lasalocid and/or echinomycin (17, 20).Linear plasmids can be transferred between Streptomyces strains by means of conjugation, and SCP1 is an example of a conjugative linear plasmid as it is easily transferred from an SCP1⁺ strain to an SCP1⁻ strain (39). Interspecific transfer to S. lividans and Streptomyces parvulus has also been reported for this plasmid, and it was demonstrated that the recipient strains had acquired the ability to produce and be resistant to methylenomycin (12, 21). Transfer of intact linear plasmids containing mercury resistance genes from two Streptomyces strains isolated from the marine environment to S. lividans, conferring mercury resistance to the initially mercury-sensitive recipient, has been reported by Ravel et al. (32). It has also been shown that interspecific transfer of linear plasmids is possible in sterile amended soil microcosms, suggesting that mercury resistance might be spread by plasmid transfer in polluted environments (31).We report here isolation and screening of several thousand actinobacterial strains from the Trondheim fjord (Norway), which resulted in identification of producers of both known and potentially new polyene macrolides with antifungal activity. The ability to produce the polyene macrolide candicidin D was found to be widespread among the Trondheim fjord Streptomyces isolates. We also report that the candicidin biosynthesis genes (can) are present on a linear plasmid identified in one of these isolates, suggesting that the can genes might be spread by means of conjugation.