Meta-analysis Reveals Different Competition Effects on Tree Growth Resistance and Resilience to Drought

Ecosystems - Drought will increasingly threaten forest ecosystems worldwide. Understanding how competition influences tree growth response to drought is essential for forest management aiming at...     

The potential of quantitative models to improve microalgae photosynthetic efficiency

The massive increase in carbon dioxide concentration in the atmosphere driven by human activities is causing huge negative consequences and new sustainable sources of energy, food and materials are highly needed. Algae are unicellular photosynthetic microorganisms that can provide a highly strategic contribution to this challenge as alternative source of biomass to complement crops cultivation. Algae industrial cultures are commonly limited by light availability, and biomass accumulation is strongly dependent on their photon‐to‐biomass conversion efficiency. Investigation of algae photosynthetic metabolism is thus strategic for the generation of more efficient strains with higher productivity. Algae are cultivated at industrial scale in conditions highly different from the natural niches they adapted to and strains development efforts must fully consider the seminal influence on productivity of regulatory mechanism of photosynthesis as well as of cultivation parameters like cells concentration, light distribution in the culture, mixing, nutrients and carbon dioxide availability. In this review we will focus in particular on how mathematical models can account for the complex influence of all environmental parameters and can be exploited for development of improved algae strains.     

Cell susceptibility to apoptosis by glutamine deprivation and rescue: Survival and apoptotic death in cultured lymphoma-leukemia cell lines

Human leukemia/lymphoma cells maintained in culture medium without provision of fresh nutrients lose viability and die by a process resembling apoptosis within a few days. Upon incubation in an FCS-supplemented RPMI 1640 medium containing 2 mM L-glutamine CEM, Namalwa, HL-60 and U937 cells, seeded at initial densities of 0.2 to 1 × 10⁶ cells/ml, ceased growing within 3–5 days and progressively entered an apoptotic pathway, as assessed by nucleosomal DNA fragmentation and morphology. Both the major energy-source nutrients in the medium, glucose and glutamine, became rapidly exhausted during the incubation. Further studies were performed using CEM cells. Incubation in glutamine-free or glucose-free medium renewed every 24 h showed that glutamine deprivation is associated with cell death by apoptosis independent of energetic failure, whereas glucose deprivation is followed by rapid loss of mitochondrial function with sharp drop of intracellular ATP and cell death by necrosis. A 12–24 h incubation in glutamine-depleted medium was required to direct the cells toward the apoptotic pathway. Growth arrest followed by apoptotic death was detected in CEM cells when medium glutamine concentration remained below 0.3–0.4 mM for at least 24 h, but a reinstatement of medium glutamine to 2 mM within this period rescued the cells from growth arrest and death. © 1996 Wiley-Liss, Inc.     

Biodemoraphy and genetics of the Berba of Benin

Genetic structure of the Berba of Benin was studied on the basis of biodemographic data and ABO, RH, MNS, KEL, JK, FY, ACP1, ADA, AK1, CA2, ESD, GLO1, G6PD, PGD, PGM1 (subtypes and thermostability), PGM2, PGP, SODA, HBα, HBβ, HBδ, BF, C3, and Hp gene frequencies. Comparisons were carried out with other populations of Benin and of sub-Sahara Africa. Correspondence analysis revealed genetic differentiation among the three main groups of populations who inhabit sub-Saharan Africa: Bushmen-Hottentots, Pygmies, and Negroes. The genetic differentiation of the Negroes in relation to their linguistic affiliation and geographic localization was evident. The first group included the populations belonging to the Bantoid subfamily of the Nigritic linguistic stock living in southern Africa; in the second subcluster the populations of central-eastern Africa were localized, and the third subcluster included the populations living in the West. © 1996 Wiley-Liss, Inc.     

Neo-adjuvant chemo-(immuno-)therapy of advanced squamous-cell head and neck carcinoma: a multicenter, phase III, randomized study comparing cisplatin + 5-fluorouracil (5-FU) with cisplatin + 5-FU + recombinant interleukin 2

We carried out an open, randomized, phase III, multicenter clinical trial to compare, in neo-adjuvant setting, the clinical response and toxicity of the combination chemotherapy cisplatin + 5-FU with the same combination plus s.c. recombinant interleukin-2 (rIL-2) in patients with advanced (stage III–IV) head and neck squamous-cell carcinoma (HNSCC). Regimen A was the classical Al Sarraf treatment: 100 mg/m² cisplatin i.v. on day 1 plus 1000 mg m⁻² day⁻¹ 5-FU on days 1–5 as a continuous infusion. Regimen B was the same as regimen A plus 4.5 MIU/day rIL-2 s.c. on days 8–12 and 15–19. Treatment was repeated every 3 weeks for three cycles. A total of 33 patients were enrolled in the study; 30 were evaluable for toxicity and 28 for response. Seventeen patients were assigned to group A and 16 were assigned to group B. Three patients (20%) of group A and 4 (31%) of group B had a complete response, 9 patients (60%) of group A and 6 (46%) of group B had a partial response, with an overall response rate of 12 patients (80%) for group A and 10 patients (77%) for group B. Two patients (13%) of group A and 3 patients (23%) group B had stable disease; 1 patient (7%) of group A had progressive disease. Thus, there was not a statistically significant difference in response rate between the two groups and therefore there was no benefit from the addition of immunotherapy with rIL-2 to the standard chemotherapy. Both regimens were well tolerated. There were 2 toxic deaths (6.7%), 1 from hematological causes in group A and 1 from cardiac causes in group B. Myelosuppression and gastrointestinal toxicity, mainly nausea/vomiting and stomatitis, were the most frequent toxicities. The calculated number of patients for the sample has not yet been reached; however, the projection of our present results suggests that it is highly improbable that a clinically significant difference between the two treatment groups will be observed even if the calculated patient sample size is achieved. Received: 9 April 1998 / Accepted: 30 June 1998     

The Arabidopsis Athb-8, -9 and genes are members of a small gene family coding for highly related HD-ZIP proteins

We report the isolation and characterization of two Arabidopsis homeobox genes highly related to the Athb-8 gene. The full-length cDNAs encode proteins of 841 and 852 amino acids which we have designated Athb-9 and -14, respectively. Athb-8, -9 and -14 are members of a small family of HD-Zip proteins (HD-ZIP III) characterized by a HD-Zip motif confined to the N-terminus of the polypeptide. The spatial organization of the HD-Zip domain of Athb-8, -9 and -14 is different from that of the Athb-1 (a member of the HD-ZIP I family) and Athb-2 (a member of the HD-ZIP II family) HD-Zip domains. DNA binding analysis performed with random-sequence DNA templates showed that the Athb-9 HD-Zip (HD-Zip-9) domain, but not the Athb-9 HD alone, binds to DNA. The HD-Zip-9 domain recognizes a 11 bp pseudopalindromic sequence (GTAAT(G/C)ATTAC), as determined by selecting high-affinity binding sites from random-sequence DNA. Moreover, gel retardation assays demonstrated that the HD-Zip-9 domain binds to DNA as a dimer. These data support the notion that the HD-ZIP III domain interacts with DNA recognition elements in a fashion similar to the HD-ZIP I and II domains.     

Understanding human cancer using Drosophila: Tid47, a cytosolic product of the DnaJ-like tumor suppressor gene l2Tid,is a novel molecular partner of patched related to skin cancer

Recessive mutations of the Drosophila gene lethal(2)-tumorous imaginal discs (l(2)tid) cause neoplastic growth of the anlagen of the adult organs, the imaginal discs. Here we report that the three proteins encoded by this evolutionarily conserved gene, Tid50, Tid47, and Tid40, identified as members of the DnaJ cochaperone family, are destined for different cellular compartments, build complexes with many proteins in a developmental stage-specific manner, and are likely to be involved in different cellular processes. We show that the cytosolic Tid47 molecule is a novel component of the Hedgehog (Hh)-Patched (Ptc) signaling regulating cell/tissue polarity and spatial patterning during development and is associated with human tumors such as basal cell carcinoma (BCC) and medulloblastoma. We provide functional evidence for its direct in vivo interaction with the Hh-bound Ptc receptor during signal transmission. Because loss of l(2)tid causes neoplastic transformation of Hh-responsive cells, we suggest that Tid47 may at least act as a guardian of the Hh signaling gradient by regulating Ptc homeostasis in the tissue. Finally, we show that the expression of htid-1, the human counterpart of l(2)tid, is altered in human BCCs. We demonstrate that in BCCs loss of htid expression correlates with loss of differentiation capacity of the neoplastic cells similar to that found in the Drosophila tumor model.     

Selective gamma-hydroxybutyric acid receptor ligands increase extracellular glutamate in the hippocampus, but fail to activate G protein and to produce the sedative/hypnotic effect of gamma-hydroxybutyric acid

Two gamma-hydroxybutyric acid (GHB) analogues, trans-gamma-hydroxycrotonic acid (t-HCA) and gamma-(p-methoxybenzyl)-gamma-hydroxybutyric acid (NCS-435) displaced [3H]GHB from GHB receptors with the same affinity as GHB but, unlike GHB, failed to displace [3H]baclofen from GABAB receptors. The effect of the GHB analogues, GHB and baclofen, on G protein activity and hippocampal extracellular glutamate levels was compared. While GHB and baclofen stimulated 5'-O-(3-[35S]thiotriphospate) [35S]GTPgammaS binding both in cortex homogenate and cortical slices, t-HCA and NCS-435 were ineffective up to 1 mm concentration. GHB and baclofen effect was suppressed by the GABAB antagonist CGP 35348 but not by the GHB receptor antagonist NCS-382. Perfused into rat hippocampus, 500 nm and 1 mm GHB increased and decreased extracellular glutamate levels, respectively. GHB stimulation was suppressed by NCS-382, while GHB inhibition by CGP 35348. t-HCA and NCS-435 (0.1-1000 microm) locally perfused into hippocampus increased extracellular glutamate; this effect was inhibited by NCS-382 (10 microm) but not by CGP 35348 (500 microm). The results indicate that GHB-induced G protein activation and reduction of glutamate levels are GABAB-mediated effects, while the increase of glutamate levels is a GHB-mediated effect. Neither t-HCA nor NCS-435 reproduced GHB sedative/hypnotic effect in mice, confirming that this effect is GABAB-mediated. The GHB analogues constitute important tools for understanding the physiological role of endogenous GHB and its receptor.     

Multiple Sclerosis Decreases Explicit Counterfactual Processing and Risk Taking in Decision Making

Introduction

Deficits in decision making (DM) are commonly associated with prefrontal cortical damage, but may occur with multiple sclerosis (MS). There are no data concerning the impact of MS on tasks evaluating DM under explicit risk, where different emotional and cognitive components can be distinguished.

Methods

We assessed 72 relapsing-remitting MS (RRMS) patients with mild to moderate disease and 38 healthy controls in two DM tasks involving risk with explicit rules: (1) The Wheel of Fortune (WOF), which probes the anticipated affects of decisions outcomes on future choices; and (2) The Cambridge Gamble Task (CGT) which measures risk taking. Participants also underwent a neuropsychological and emotional assessment, and skin conductance responses (SCRs) were recorded.

Results

In the WOF, RRMS patients showed deficits in integrating positive counterfactual information (p<0.005) and greater risk aversion (p<0.001). They reported less negative affect than controls (disappointment: p = 0.007; regret: p = 0.01), although their implicit emotional reactions as measured by post-choice SCRs did not differ. In the CGT, RRMS patients differed from controls in quality of DM (p = 0.01) and deliberation time (p = 0.0002), the latter difference being correlated with attention scores. Such changes did not result in overall decreases in performance (total gains).

Conclusions

The quality of DM under risk was modified by MS in both tasks. The reduction in the expression of disappointment coexisted with an increased risk aversion in the WOF and alexithymia features. These concomitant emotional alterations may have implications for better understanding the components of explicit DM and for the clinical support of MS patients.     

Effect of sodium chloride on the gelatinization of starch: a multimeasurement study.

The effect of sodium chloride on the gelatinization and rheological properties of wheat and potato starches has been studied using differential scanning calorimetry, dynamic mechanical thermal analysis, and electron spin resonance techniques. All samples contained 60% water (w/w wet starch basis) and the salt content ranged from 0 to 16% (g/100 g starch-water). The presence of salt affected the onset (T(o)), peak (T(p)), and end (T(e)) temperatures of gelatinization, gelatinization enthalpy (DeltaH), storage modulus (G'), and rotational mobility coefficient (D(rot)), and the effect differed by salt concentration. 1H-NMR was used in parallel in order to elucidate how salts affect the properties of water in starch suspensions and in aqueous salt solutions according to their position on the Hofmeister series classification. The obtained results suggest that the mechanism of starch gelatinization in salt solutions can be attributed to the effect of solute on water properties and direct polymer-solute interactions. These two effects conflict with one another and result in complex effect patterns depending on the concentration of the salts.