Late-Holocene fossil evidence and the interpretation of the vegetation in NW Iberia: management issues in the light of palaeoecological findings

Vegetation History and Archaeobotany - The management of the forests of Pinus sylvestris L. in north-western Iberia has been subjected to intense debate as the tree has been long considered an...     

Chloride as a macronutrient increases water‐use efficiency by anatomically driven reduced stomatal conductance and increased mesophyll diffusion to CO2

Chloride (Cl^?) has been recently described as a beneficial macronutrient, playing specific roles in promoting plant growth and water‐use efficiency (WUE). However, it is still unclear how Cl^? could be beneficial, especially in comparison with nitrate (NO₃^?), an essential source of nitrogen that shares with Cl^? similar physical and osmotic properties, as well as common transport mechanisms. In tobacco plants, macronutrient levels of Cl^? specifically reduce stomatal conductance (g_s) without a concomitant reduction in the net photosynthesis rate (A_N). As stomata‐mediated water loss through transpiration is inherent in the need of C₃ plants to capture CO₂, simultaneous increase in photosynthesis and WUE is of great relevance to achieve a sustainable increase in C₃ crop productivity. Our results showed that Cl^?‐mediated stimulation of larger leaf cells leads to a reduction in stomatal density, which in turn reduces g_s and water consumption. Conversely, Cl^? improves mesophyll diffusion conductance to CO₂ (g_m) and photosynthetic performance due to a higher surface area of chloroplasts exposed to the intercellular airspace of mesophyll cells, possibly as a consequence of the stimulation of chloroplast biogenesis. A key finding of this study is the simultaneous improvement of A_N and WUE due to macronutrient Cl^? nutrition. This work identifies relevant and specific functions in which Cl^? participates as a beneficial macronutrient for higher plants, uncovering a sustainable approach to improve crop yield.     

Intrinsic competition between resident and invasive parasitoids (Hymenoptera: Braconidae) that attack the West Indian fruit fly Anastrepha obliqua under field conditions

We evaluated under semi-field conditions the intrinsic competition between Diachasmimorpha longicaudata (Ashmead), as an invasive parasitoid, and Doryctobracon areolatus (Szépligeti) and Utetes anastrephae (Viereck) (all Hymenoptera: Braconidae) as resident parasitoids, as well as that between U. anastrephae as an invader and D. areolatus as a resident. The percentage of live D. areolatus larvae decreased by 39.8% and 29.4% following attack by D. longicaudata and U. anastrephae as invasive parasitoids, respectively. Likewise, the parasitism percentage of D. areolatus decreased by 31.5% and 60.8% under competition with the invasive parasitoids D. longicaudata and U. anastrephae, respectively. Parasitism by D. longicaudata decreased by 44.6% and 41.6% in the presence of the residents D. areolatus and U. anastrephae, respectively, while parasitism of U. anastrephae was only affected when this species was a resident. We concluded that D. areolatus is an inferior intrinsic competitor and that U. anastrephae resists the competitive presence of D. longicaudata.     

Sterility of the coffee berry borer,Hypothenemus hampei (Coleoptera: Curculionidae), caused by the nematode Metaparasitylenchus hypothenemi (Tylenchidae: Allantonematidae)

Metaparasitylenchus hypothenemi is an endoparasitic nematode that causes partial or total sterility of coffee berry borer (Hypothenemus hampei) females, although the causes are unknown. Fecundity and the average size of the common and lateral oviduct, vitellarium, and germarium in the four ovarioles (I, II, III and IV) were compared between parasitised and non-parasitised insects to determine the causes of sterility. The nematode significantly lowers the number of oocytes and 86% of parasitised insects (24 out of 28 insects) were sterile, while fecundity in the remaining 13% was non-significantly different to that in non-parasitised insects. No significant differences were recorded in the size of the common oviduct, lateral oviduct, vitellarium, and germarium between parasitised and non-parasitised insects and the nematode does not cause any apparent damage on the surface of the ovary.     

Seedling response to water stress in valley oak (Quercus lobata) is shaped by different gene networks across populations

Drought is a major stress for plants, creating a strong selection pressure for traits that enable plant growth and survival in dry environments. Many drought responses are conserved species‐wide responses, while others vary among populations distributed across heterogeneous environments. We tested how six populations of the widely distributed California valley oak (Quercus lobata) sampled from contrasting climates would differ in their response to soil drying relative to well‐watered controls in a common environment by measuring ecophysiological traits in 93 individuals and gene expression (RNA‐seq) in 42 individuals. Populations did not differ in their adjustment of turgor loss point during soil drying, suggesting a generalized species‐wide response. Differential expression analysis identified 689 genes with a common response to treatment across populations and 470 genes with population‐specific responses. Weighted gene co‐expression network analysis (WGCNA) identified groups of genes with similar expression patterns that may be regulated together (gene modules). Several gene modules responded differently to water stress among populations, suggesting regional differences in gene network regulation. Populations from sites with a high mean annual temperature responded to the imposed water stress with significantly greater changes in gene module expression, indicating that these populations may be locally adapted to respond to drought. We propose that this variation among valley oak populations provides a mechanism for differential tolerance to the increasingly frequent and severe droughts in California.     

Willingness of rural communities to reforest with native tree species in central Chile

Economic development of rural people is not always feasible along with concomitant forest restoration, especially when meager reforestation incentives are oriented to poor rural people who probably are not willing to plant native species in their small plots of land. Forest restoration incentives have been created by the Chilean government to engage poor rural people in reforestation using native tree species to recover degraded lands. Our objective was to compare the willingness of people from rural communities to plant native species if they had to bear the costs or if the government did, and we related the answers to environmental and socioeconomic variables. Of the 217 respondents 53.9% were interested in planting native trees if subsidies became available. Interest decreased if the respondents had to pay for the cost, but only slightly. The willingness to reforest was significantly greater at lower distance from the community to the nearest native forest for those with lower income level, and was higher when there was use of nontimber forest products or wood by the respondents. However, in spite of the positive disposition to plant native trees, only 23% of the respondents were interested in planting on their own land, which is a requirement to receive the economic incentives. Most respondents were willing to plant in open sites and on degraded hillsides that surround their communities. We conclude that despite monetary incentives, benefits cannot reach most rural inhabitants because of their lack of interest in reforesting their own land.     

Hydrogen sulfide alleviates uranium‐induced rat hepatocyte cytotoxicity via inhibiting Nox4/ROS/p38 MAPK pathway

As a gasotransmitter, hydrogen sulfide (H₂S) plays a crucial role in regulating the signaling pathway mediated by oxidative stress. The purpose of this study was to investigate the protective effects of H ₂S on uranium‐induced rat hepatocyte cytotoxicity. Primary hepatocytes were isolated and cultured from Sprague Dawley rat liver tissues. After pretreating with sodium hydrosulfide (an H ₂S donor) for 1 hour (or GKT‐136901 for 30 minutes), hepatocytes were treated by uranyl acetate for 24 hours. Cell viability, reactive oxygen species (ROS), malondialdehyde (MDA), NADPH oxidase 4 (Nox4), and p38 mitogen‐activated protein kinase (p38 MAPK) phosphorylation were respectively determined. The effects of direct inhibition of Nox4 expression by GKT‐136901 (a Nox4 inhibitor) on ROS and phospho‐p38 MAPK levels were examined in uranium‐treated hepatocytes. The results implicate that H ₂S can afford protection of rat hepatocytes against uranium‐induced adverse effects through attenuating oxidative stress via prohibiting Nox4/ROS/p38 MAPK signaling.     

Overexpression of RYBP inhibits proliferation,invasion, and chemoresistance to cisplatin in anaplastic thyroid cancer cells via the EGFR pathway

Ring1 and YY1 binding protein (RYBP), a new member of the polycomb group protein family, has been reported to play an important role in various biological processes. Recently, more and more studies have demonstrated an implication of RYBP in cancer development. However, the specific role of RYBP in anaplastic thyroid cancer (ATC) remains unknown. In this study, we investigated for the first time the expression pattern and biological functions of RYBP in ATC. We showed that RYBP was lowly expressed in ATC tissues and cell lines. We also found that overexpression of RYBP inhibited ATC cell proliferation, invasion, and cisplatin resistance. Furthermore, we observed that upregulation of RYBP decreased the phosphorylation of EGFR and ERK1/2 in ATC cells. Taken together, our data indicated that RYBP might be considered as a promising therapeutic target for the treatment of ATC.