scholarly journals Divergence of stem biomechanics and hydraulics between Bauhinia lianas and trees

AoB Plants ◽  
2021 ◽  
Author(s):  
Yan Xiao ◽  
Yu Song ◽  
Fu-Chuan Wu ◽  
Shu-Bin Zhang ◽  
Jiao-Lin Zhang
Keyword(s):  
Mechanical Strength ◽  
Common Garden ◽  
Life Forms ◽  
Modulus Of Rupture ◽  
Hydraulic Efficiency ◽  
Growth And Survival ◽  
The Past ◽  
Conduit Wall ◽  
Lower Stem ◽  
Seasonal Forests

Abstract Liana abundance and biomass are increasing in neotropical and Asian tropical seasonal forests over the past decades. Stem mechanical properties and hydraulic traits influence the growth and survival of plants, yet the differences in stem mechanical and hydraulic performance between congeneric lianas and trees remain poorly understood. Here, we measured 11 stem mechanical and hydraulic traits for 10 liana species and 10 tree species from Bauhinia grown in a tropical common garden. Our results showed that Bauhinia lianas possessed lower stem mechanical strength as indicated by both modulus of elasticity and modulus of rupture, and higher stem potential hydraulic conductivity than congeneric trees. Such divergence was mainly attributed to the differentiation in liana and tree life forms. Whether the phylogenetic effect was considered or not, mechanical strength was positively correlated with wood density, vessel conduit wall reinforcement and sapwood content across species. Results of principle component analysis showed that traits related to mechanical safety and hydraulic efficiency were loaded in the opposite direction, suggesting a trade-off between biomechanics and hydraulics. Our results provide evidence for obvious differentiation in mechanical demand and hydraulic efficiency between congeneric lianas and trees.

Stability and Folding of the Unusually Stable Hemoglobin from Synechocystis is Subtly Optimized and Dependent on the Key Heme Pocket Residues.

2020 ◽  
Vol 27 ◽  
Author(s):  
Sheetal Uppal ◽  
Mohd. Asim Khan ◽  
Suman Kundu
Keyword(s):  
Molten Globule ◽  
Life Forms ◽  
Model System ◽  
Heme Pocket ◽  
The Past ◽  
Specific Manner ◽  
Delivery Vehicles ◽  
The Stability ◽  
Key Residues ◽  
Synechocystis Sp

Aims: The aim of our study is to understand the biophysical traits that govern the stability and folding of Synechocystis hemoglobin, a unique cyanobacterial globin that displays unusual traits not observed in any of the other globins discovered so far. Background: For the past few decades, classical hemoglobins such as vertebrate hemoglobin and myoglobin have been extensively studied to unravel the stability and folding mechanisms of hemoglobins. However, the expanding wealth of hemoglobins identified in all life forms with novel properties, like heme coordination chemistry and globin fold, have added complexity and challenges to the understanding of hemoglobin stability, which has not been adequately addressed. Here, we explored the unique truncated and hexacoordinate hemoglobin from the freshwater cyanobacterium Synechocystis sp. PCC 6803 known as “Synechocystis hemoglobin (SynHb)”. The “three histidines” linkages to heme are novel to this cyanobacterial hemoglobin. Objective: Mutational studies were employed to decipher the residues within the heme pocket that dictate the stability and folding of SynHb. Methods: Site-directed mutants of SynHb were generated and analyzed using a repertoire of spectroscopic and calorimetric tools. Result: The results revealed that the heme was stably associated to the protein under all denaturing conditions with His117 playing the anchoring role. The studies also highlighted the possibility of existence of a “molten globule” like intermediate at acidic pH in this exceptionally thermostable globin. His117 and other key residues in the heme pocket play an indispensable role in imparting significant polypeptide stability. Conclusion: Synechocystis hemoglobin presents an important model system for investigations of protein folding and stability in general. The heme pocket residues influenced the folding and stability of SynHb in a very subtle and specific manner and may have been optimized to make this Hb the most stable known as of date. Other: The knowledge gained hereby about the influence of heme pocket amino acid side chains on stability and expression is currently being utilized to improve the stability of recombinant human Hbs for efficient use as oxygen delivery vehicles.

scholarly journals Involvement of CesA4, CesA7-A/B and CesA8-A/B in secondary wall formation in Populus trichocarpa wood

2019 ◽  
Vol 40 (1) ◽  
pp. 73-89 ◽  
Author(s):  
Manzar Abbas ◽  
Ilona Peszlen ◽  
Rui Shi ◽  
Hoon Kim ◽  
Rui Katahira ◽  
...  
Keyword(s):  
Solid State ◽  
Mechanical Strength ◽  
Cell Walls ◽  
Secondary Wall ◽  
Populus Trichocarpa ◽  
Wood Formation ◽  
Fiber Cell ◽  
Modulus Of Rupture ◽  
Cellulose Content ◽  
Wall Formation

Abstract Cellulose synthase A genes (CesAs) are responsible for cellulose biosynthesis in plant cell walls. In this study, functions of secondary wall cellulose synthases PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B were characterized during wood formation in Populus trichocarpa (Torr. & Gray). CesA RNAi knockdown transgenic plants exhibited stunted growth, narrow leaves, early necrosis, reduced stature, collapsed vessels, thinner fiber cell walls and extended fiber lumen diameters. In the RNAi knockdown transgenics, stems exhibited reduced mechanical strength, with reduced modulus of rupture (MOR) and modulus of elasticity (MOE). The reduced mechanical strength may be due to thinner fiber cell walls. Vessels in the xylem of the transgenics were collapsed, indicating that water transport in xylem may be affected and thus causing early necrosis in leaves. A dramatic decrease in cellulose content was observed in the RNAi knockdown transgenics. Compared with wildtype, the cellulose content was significantly decreased in the PtrCesA4, PtrCesA7 and PtrCesA8 RNAi knockdown transgenics. As a result, lignin and xylem contents were proportionally increased. The wood composition changes were confirmed by solid-state NMR, two-dimensional solution-state NMR and sum-frequency-generation vibration (SFG) analyses. Both solid-state nuclear magnetic resonance (NMR) and SFG analyses demonstrated that knockdown of PtrCesAs did not affect cellulose crystallinity index. Our results provided the evidence for the involvement of PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B in secondary cell wall formation in wood and demonstrated the pleiotropic effects of their perturbations on wood formation.

scholarly journals Effect of Moderate Temperature Thermal Modification Combined with Wax Impregnation on Wood Properties

2020 ◽  
Vol 10 (22) ◽  
pp. 8231
Author(s):  
Jing-Wen Zhang ◽  
Hong-Hai Liu ◽  
Lin Yang ◽  
Tian-Qi Han ◽  
Qin Yin
Keyword(s):  
Mechanical Strength ◽  
Dimensional Stability ◽  
Color Change ◽  
Strength Loss ◽  
Wood Properties ◽  
Thermal Modification ◽  
Moderate Temperature ◽  
Modulus Of Rupture ◽  
Internal Surfaces ◽  
Higher Temperature

Thermal modification (TM) improves the hydrophobicity, dimensional stability, and durability of wood, but TM commonly results in severe color change and mechanical strength loss as wood is treated at higher temperature. In this study, Pterocarpus macrocarpus Kurz wood was thermally modified at moderate temperature (150 °C) and higher temperature (200 °C), and subsequently TM wood at 150 °C was subjected to wax impregnation (WI), the effect of a combination of TM and WI on the hygroscopicity, dimensional stability, and mechanical properties, as well as the micro-structure of wood, were investigated and compared. The results showed that the mass loss of wood was slight at 150 °C TM, while it became severe at 200 °C TM conditions. TM conditions affected the amount of the subsequent wax impregnation; the equilibrium moisture content (EMC), water absorption ratio, and adsorption and absorption swelling of the 150 °C TM + WI group were lower than that of 200 °C TM, and presented the lowest value. Moderate temperature TM could improve the hydrophobicity and dimensional stability of wood, but WI played a key role in the improvement. TM decreased the modulus of rupture (MOR) of wood, while WI improved the MOR. TM increased the modulus of elasticity (MOE) of wood, but WI had little effect on MOE; Scanning electron microscope (SEM) observation showed that the wax was successfully impregnated into the wood interior, and presented an even distribution on the internal surfaces of wood cells; Fourier-transform infrared spectroscopy (FTIR) spectra verified the changes of –OH and C=O after TM and TM + WI, which contributed to decreasing hygroscopicity and improving the dimensional stability of the wood. Impregnated wax improved wood mechanical strength, but decreased the lightness, and deepened the color of wood. The combination of thermal modification at moderate temperature with subsequent wax impregnation is a practical approach for improving wood properties.

scholarly journals Vulnerability to cavitation, hydraulic efficiency, growth and survival in an insular pine (Pinus canariensis)

2013 ◽  
Vol 111 (6) ◽  
pp. 1167-1179 ◽  
Author(s):  
Rosana López ◽  
Unai López de Heredia ◽  
Carmen Collada ◽  
Francisco Javier Cano ◽  
Brent C. Emerson ◽  
...  
Keyword(s):  
Hydraulic Efficiency ◽  
Pinus Canariensis ◽  
Growth And Survival ◽  
Vulnerability To Cavitation

scholarly journals First inventory of vascular flora of Matokit mountain (Biokovo massif, Croatia)

2020 ◽  
Vol 144 (5-6) ◽  
pp. 257-268
Author(s):  
Ivana Vitasović-Kosić ◽  
Mara Vukojević ◽  
Sandro Bogdanović
Keyword(s):  
Mediterranean Climate ◽  
Invasive Plant ◽  
Vascular Plant ◽  
Life Forms ◽  
Herbarium Specimens ◽  
Vascular Flora ◽  
The Past ◽  
Floristic Data ◽  
High Influence ◽  
Southern Croatia

The vascular flora of Matokit Mt (Biokovo Massif) in southern Croatia was researched in different vegetation periods from 2010-2015, and a total of 604 vascular plant taxa belonging to 86 families and 337 genera were found. The studied area has never been studied in the past and these are the first detailed floristic data about grasslands in different succession stages of Matokit Mt. Collected herbarium specimens (345 sheets) were digitalized and are available at the ZAGR Virtual Herbarium. The most dominant families were legumes (Fabaceae 9.9%), grasses (Poaceae 9.1%), daisies (Asteraceae 7.4%) and mints (Lamiaceae 6.8%). The analysis of life forms shows the dominance of hemicryptophytes (39.9%) and therophytes (26.2%) on Matokit Mt that indicates a high influence of the Mediterranean climate. A total of 36 endangered and 17 invasive plant taxa across the whole studied area were recorded. Endemic are 32 plant taxa (26 endemics in a broader sense and 6 stenoendemics) and they represent new site of Croatian flora. The occurrence of some very rare endemics (Cardamine fialae Fritsch and Erysimum croaticum Polatschek) in the flora of Matokit Mt is of special interest for the national flora.

The Clay Figurines of Acambaro, Guanajuato, Mexico

1953 ◽  
Vol 18 (4) ◽  
pp. 388-389 ◽  
Author(s):  
Charles C. Di Peso
Keyword(s):  
Life Forms ◽  
The State ◽  
Modern Life ◽  
The Past ◽  
Private Collection

For the past eight years, stories have appeared concerning a vast collection of animal and human figurines of great antiquity, gathered in the vicinity of Acambaro in the state of Guanajuato, Mexico. Senor Waldemar Julsrud possesses some 32,000 of these artifacts in his private collection. These ceramic figures consist of such forms as Brontosaurus, Tyrannosaurus Rex, Stegosaurus, Trachodon, Dimetrodon and other Mesozoic reptilian life-forms. Also included in the collection are a number of modern life-forms such as cow, horse, hippopotamus, elephant, rabbit, and dog. Even more fabulous is the number of miniature Egyptian sarcophagi found in the collection.

The anatomical basis of the link between density and mechanical strength in mangrove branches

2013 ◽  
Vol 40 (4) ◽  
pp. 400 ◽  
Author(s):  
Nadia S. Santini ◽  
Nele Schmitz ◽  
Vicki Bennion ◽  
Catherine E. Lovelock
Keyword(s):  
Mechanical Strength ◽  
Avicennia Marina ◽  
Modulus Of Rupture ◽  
Carbon Gain ◽  
Bruguiera Gymnorrhiza ◽  
Mangrove Species ◽  
Rhizophora Stylosa ◽  
Anatomical Characteristics ◽  
Trade Offs ◽  
Anatomical Basis

Tree branches are important as they support the canopy, which controls photosynthetic carbon gain and determines ecological interactions such as competition with neighbours. Mangrove trees are subject to high wind speeds, strong tidal flows and waves that can damage their branches. The survival and establishment of mangroves partly depend on the structural and mechanical characteristics of their branches. In addition, mangroves are exposed to soils that vary in salinity. Highly saline conditions can increase the tension in the water column, imposing mechanical stresses on the xylem vessels. Here, we investigated how mechanical strength, assessed as the modulus of elasticity (MOE) and the modulus of rupture (MOR), and density relate to the anatomical characteristics of intact mangrove branches from southeast Queensland and whether the mechanical strength of branches varies among mangrove species. Mechanical strength was positively correlated with density of mangrove intact branches. Mechanical strength (MOE) varied among species, with Avicennia marina (Forssk.) Vierh. branches having the highest mechanical strength (2079 ± 176 MPa), and Rhizophora stylosa Griff. and Bruguiera gymnorrhiza (L.) Savigny ex Lam. and Poiret having the lowest mechanical strength (536.8 ± 39.2 MPa in R. stylosa and 554 ± 58.2 MPa in B. gymnorrhiza). High levels of mechanical strength were associated with reductions in xylem vessel lumen area, pith content and bark content, and positively associated with increases in fibre wall thickness. The associations between mechanical strength and anatomical characteristics in mangrove branches suggest trade-offs between mechanical strength and water supply, which are linked to tree growth and survival.

scholarly journals Life form dynamics of the tree layer in evergreen and deciduous broad-leaved mixed forest during 1996–2017 in Tianmu Mountains, eastern China

Silva Fennica ◽  
2020 ◽  
Vol 54 (2) ◽  
Author(s):  
Cheng Bai ◽  
Shixue You ◽  
Weipeng Ku ◽  
Qilin Dai ◽  
Zhengyi Wang ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Life Form ◽  
Eastern China ◽  
Mixed Forest ◽  
Small Diameter ◽  
Life Forms ◽  
Recruitment Rate ◽  
Diameter Class ◽  
Evergreen Species ◽  
The Past

In the forest areas of eastern China, there is a change from forest dominated by deciduous broad-leaved trees to forest dominated by evergreen broad-leaved trees as the latitude or altitude decreases. Different life forms have different survival strategies to deal with climate change, and studying the life form dynamics of the tree layers in the mixed forest in eastern China, with increasing temperature, can help us understand how the forest responds. This study was performed in a 1 ha plot in evergreen and deciduous broad-leaved mixed forest in Tianmu Mountain National Nature Reserve. Based on the data from two surveys (1996 and 2017), the changes in life form composition and biodiversity over the past 21 years were analyzed. We obtained the following results: (1) The proportion of evergreen trees increased from 55.0% in 1996 to 67.5% in 2017, and the dominance of evergreen species was enhanced. (2) The diversity of both life forms increased, and the tree species were more abundant. (3) The average annual recruitment rate of the evergreen species was 2.1% greater than their mortality rate, and the average annual recruitment rate of the deciduous species was 0.5% less than their mortality rate. (4) The competition among the trees in the small-diameter class (10 cm ≤ DBH < 20 cm) was fierce for many tree species. The proportion of the evergreen species in the small-diameter class was high. The life forms making up the mixed climax forest community has changed over the past 21 years, with the proportion and dominance of evergreen trees increasing significantly.

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