Pre-and post-pollination barriers between two exotic and five native Sagittaria species:Implications for species conservation

Anthropogenic introduction of species has resulted in a breakdown of geographical barriers and hybridization in previously allopatric species.Thus,examining hybridization proneness of exotic species contributes to revealing its potential threat.Moreover,reproductive barriers may be strengthened or weakened due to long-term geographical isolation for these newly sympatric species.However,few studies have evaluated multiple barriers between alien and native species.In this study,we quantified the importance of four pre-pollination barriers(phenological,floral traits,pollen production,and floral constancy)and four post-pollination barriers(pollen-pistil incompatibility,seed set,seed viability,and seedling survival)between two introduced and five native Sagittaria species.Results showed that introduced S.platyphylla was cross-compatible with two native species,whereas introduced S.montevidensis was incapable of hybridizing with any native species.Different barriers were asymmetric within species pairs and multiple barriers acted in concert to maintain species boundaries.Postpollination barriers contributed more to total reproductive isolation in native species,whereas prepollination barriers played a stronger role in total reproductive isolation for two introduced species.Seed set was the only barrier that was positively correlated with genetic distance.Our results provide a perspective to better understand reproductive barriers for secondary contact species.We highlight the importance of monitoring hybridization events before human introduction and the possible conservation strategies to remove invasive species with hybridization proneness.

Fish oil-containing lipid emulsions prevention on parenteral nutrition-associated cholestasis in very low birth weight infants:a meta-analysis

Background The effect of fish oil-containing lipid emulsions on preventing parenteral nutrition-associated cholestasis(PNAC)in very low birth weight(VLBW)infants is not known.Thus,we conducted a meta-analysis to identify any preven-tion effect.Methods PubMed,EMBASE,and CENTRAL were searched up to 26 January 2021 for studies related to the preventive effect of fish oil-containing lipid emulsions and fish oil-free lipid emulsions on cholestasis in VLBW infants.Revman 5.3 was used to synthesize the results.A fixed-effect model was used to summarize the data when the heterogeneity was non-significant(I2<50%),and a random-effects model was used when the heterogeneity was significant(I2>50%).Results Of 728 articles,11 randomized controlled trials met the inclusion criteria.The meta-analysis indicated that fish oil-containing lipid emulsion reduced the occurrence of PNAC significantly with risk ratio(RR)=0.53,95%confidence interval(CI)0.36-0.80,P=0.002.The heterogeneity was non-significant with I2=23%.Subgroup analysis based on par-enteral nutrition duration and median birth weight was performed.The synthesis results for patients with parenteral nutri-tion duration exceeding 14 days revealed I2=35%(P=0.15)and pooled RR=0.47,95%CI 0.30-0.73,P=0.0008;and for patients with duration less than 14 days revealed I2=0%(P=0.72)and pooled RR=1.14,95%CI 0.39-3.35,P=0.81.The synthesis for patients with birth weight more than 1000 g revealed I2=0%(P=0.41)and pooled RR=0.55,95%CI 0.26-1.18,P=0.12;and for patients with birth weight below 1000 g revealed I2=44%(P=0.11)and pooled RR=0.53,95%CI 0.33-0.85,P=0.009.Conclusions The fish oil-containing lipid emulsion can reduce the occurrence of PNAC in VLBW infants based on the avail-able original randomized controlled trial studies,especially for patients with parenteral nutrition duration exceeding 14 days and extremely low birth weight infants.Future studies should be performed before a definitive conclusion can be established.

A review of solute-point defect interactions in vanadium and its alloys: first-principles modeling and simulation

Vanadium alloys are the promising first wall and blanket materials for fusion reactors.Large amounts of helium(He)and hydrogen(H)impurities are produced inside the materials along with irradiation defects under neutron irradiation,leading to bubble formation and microstructure changes,which will degrade the thermal and mechanical properties of vanadium alloys.The microstructure changes of materials are influenced by the interactions of point defects with solute atoms.Nowadays,first-principles calculations are intensively performed to elucidate these interactions,clustering,and dissolution,which can provide valuable information for the design of high-performance anti-irradiation materials.This paper reviews the recent findings of the interactions of point defects(vacancies,self-interstitial atoms)with substitutional solutes and interstitial solutes(C,O,N,H,and He)as well as their clusters in vanadium and its alloys from first-principles calculations.