scholarly journals What does ‘toughness’ look like? An examination of the breakdown of young and mature leaves under cyclical loading

2021 ◽  
Vol 11 (5) ◽  
pp. 20200087 ◽  
Author(s):  
Jordan Traff ◽  
David J. Daegling
Keyword(s):  
Mechanical Testing ◽  
Axial Loading ◽  
Testing System ◽  
Displacement Control ◽  
Gradual Decline ◽  
Leaf Toughness ◽  
Mature Leaves ◽  
Young Leaves ◽  
Cyclical Loading ◽  
Repetitive Loading

The material property of leaf toughness is considered the crucial mechanical challenge facing folivorous primates. Mature leaves have higher recorded toughness values than young leaves on average, leading to many assumptions about the patterning of food breakdown that follow a tough/not-tough dichotomy. We tested three hypotheses about how leaves break down under repetitive loading cycles, predicting that mature leaves (i) experience more force during simulated occlusal loads, (ii) more effectively resist fragmentation into small pieces, and (iii) show a more gradual decline in resistance over consecutive cycles than young leaves. Under displacement control using a mechanical testing system, we subjected young and mature leaves to 20 cycles of axial loading using interlocking steel wedges, then collected and quantified the size of the leaf fragments. While we found that mature leaves experienced more overall force than young leaves ( p < 0.001), they also shattered into smaller pieces ( p = 0.004) and showed a steeper decline in their resistance to the cycles over the course of a test ( p < 0.01). These results suggest that putatively ‘tougher’ foods (i.e. mature versus young leaves) do not necessarily resist fragmentation as commonly assumed. The current tough/not-tough paradigm of primate foods may not accurately reflect how leaves break down during masticatory behaviour.

Karakter Morfologi Daun Ubi Jalar Sebagai Bahan Pangan Suku Dani Distrik Kurulu Jayawijaya

Agrotek ◽  
2018 ◽  
Vol 2 (3) ◽  
Author(s):  
Antonius Suparno ◽  
Opalina Logo ◽  
Dwiana Wasgito Purnomo
Keyword(s):  
Sweet Potato ◽  
Leaf Morphology ◽  
Food Source ◽  
Staple Food ◽  
Sweet Potatoes ◽  
General Outline ◽  
Leaf Vein ◽  
Mature Leaves ◽  
Young Leaves ◽  
Tuber Roots

Sweet potato serves as a staple food for people in Jayawijaya. Many cultivars of sweet potatoes have been cultivated by Dani tribe in Kurulu as foot for their infant, child and adult as well as feeding especially for pigs. Base on the used of sweet potatoes as food source for infant and child, this study explored 10 different cultivars. As for the leaf morphology, it was indentified that the mature leaves have size around 15 � 18 cm. general outline of the leaf is reniform (40%), 60% have green colour leaf, 50% without leaf lobe, 60% of leaf lobes number is one, 70% of shape of central leaf lobe is toothed. Abazial leaf vein pigmentation have purple (40%), and petiole pigmentation is purple with green near leaf (60%), besides its tuber roots, sweet potatoes are also harvested for its shoots and green young leaves for vegetables.

scholarly journals The role of JrPPOs in the browning of walnut explants

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shugang Zhao ◽  
Hongxia Wang ◽  
Kai Liu ◽  
Linqing Li ◽  
Jinbing Yang ◽  
...  
Keyword(s):  
Tissue Culture ◽  
Production Efficiency ◽  
Phenolic Content ◽  
Leaf Tissue ◽  
Limiting Factor ◽  
Mature Leaves ◽  
Survival Percentage ◽  
Highly Active ◽  
Young Leaves

Abstract Background Tissue culture is an effective method for the rapid breeding of seedlings and improving production efficiency, but explant browning is a key limiting factor of walnut tissue culture. Specifically, the polymerization of PPO-derived quinones that cause explant browning of walnut is not well understood. This study investigated explants of ‘Zanmei’ walnut shoot apices cultured in agar (A) or vermiculite (V) media, and the survival percentage, changes in phenolic content, POD and PPO activity, and JrPPO expression in explants were studied to determine the role of PPO in the browning of walnut explants. Results The results showed that the V media greatly reduced the death rate of explants, and 89.9 and 38.7% of the explants cultured in V media and A media survived, respectively. Compared with that of explants at 0 h, the PPO of explants cultured in A was highly active throughout the culture, but activity in those cultured in V remained low. The phenolic level of explants cultured in A increased significantly at 72 h but subsequently declined, and the content in the explants cultured in V increased to a high level only at 144 h. The POD in explants cultured in V showed high activity that did not cause browning. Gene expression assays showed that the expression of JrPPO1 was downregulated in explants cultured in both A and V. However, the expression of JrPPO2 was upregulated in explants cultured in A throughout the culture and upregulated in V at 144 h. JrPPO expression analyses in different tissues showed that JrPPO1 was highly expressed in stems, young leaves, mature leaves, catkins, pistils, and hulls, and JrPPO2 was highly expressed in mature leaves and pistils. Moreover, browning assays showed that both explants in A and leaf tissue exhibited high JrPPO2 activity. Conclusion The rapid increase in phenolic content caused the browning and death of explants. V media delayed the rapid accumulation of phenolic compounds in walnut explants in the short term, which significantly decreased explants mortality. The results suggest that JrPPO2 plays a key role in the oxidation of phenols in explants after branch injury.

Effect of Induced Incomplete Ossification of the Humeral Condyle on Ex Vivo Humeral Condylar Biomechanics

2020 ◽  
Author(s):  
Logan M. Scheuermann ◽  
Michael G. Conzemius
Keyword(s):  
Mechanical Testing ◽  
Study Design ◽  
Ex Vivo ◽  
Peak Load ◽  
Testing System ◽  
Condylar Fracture ◽  
Naturally Occurring ◽  
Left And Right ◽  
Condylar Fractures ◽  
Humeral Condyle

Abstract Objective The aim of this study was to investigate the effects of an induced incomplete ossification of the humeral condyle (IOHC) lesion on ex vivo canine humeral condylar biomechanics. Study Design Nine paired cadaveric elbows were collected from mature dogs weighing between 20 and 25 kg. Left and right limbs were randomized to IOHC or normal groups. Limbs were prepared for mechanical testing; ligaments were preserved and an IOHC lesion was created. Elbows were potted, positioned into a biomaterials testing system at an angle of 135 degrees and axially loaded to failure at a rate of 30 mm/minute. Results Induced IOHC lesions reduced peak load (p = 0.02) when compared with an intact humerus. There was no difference between stiffness (p = 0.36) of intact humeri or humeri with an induced IOHC lesion. An induced IOHC lesion increased (p = 0.012) the probability of intracondylar fracture under load. Conclusion Cadaveric humeri are weakened by the creation of an intracondylar osteotomy and fractures secondary to induced IOHC are similar to spontaneous humeral condylar fractures. These findings support the hypothesis that naturally occurring IOHC weakens the humeral condyle and may predispose to humeral condylar fracture.

scholarly journals Meteorological conditions, ozone concentration and leaf age affect gas exchange in Psidium guajava ‛Palumaʼ

Hoehnea ◽  
2017 ◽  
Vol 44 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Juliana Moreno Pina ◽  
Sérgio Tadeu Meirelles ◽  
Regina Maria de Moraes
Keyword(s):  
Gas Exchange ◽  
Ozone Concentration ◽  
Leaf Age ◽  
Psidium Guajava ◽  
Meteorological Conditions ◽  
Gas Exchanges ◽  
Mature Leaves ◽  
Young Leaves ◽  
Entire Experiment ◽  
The City

ABSTRACT This study aimed to investigate the importance of leaf age, meteorological conditions and ozone concentration (O3) on gas exchange of Psidium guajava ‛Paluma'. Saplings were grown and exposed in standard conditions in the city of São Paulo, in six periods of three months with weekly measurements in young and mature leaves. Gas exchanges were higher in young leaves for almost the entire experiment. Mature leaves showed greater reduction in gas exchange. The multivariate analysis of biotic and abiotic variables indicated that vapor pressure deficit (VPD), O3 concentration and radiation were the main variables associated with gas exchange decrease in young leaves. In mature leaves the influence of VPD is lower, but the temperature importance is higher. Moreover, the opposition between assimilation and O3 is more evident in mature leaves, indicating their greater sensitivity to O3.

scholarly journals Antioxidant Activity Sonneratia caseolaris Leaves Extract at Different Maturity Stages

2020 ◽  
Vol 8 (3) ◽  
pp. 130
Author(s):  
Winarti Winarti ◽  
Boedi Setya Rahardja ◽  
Sudarno Sudarno
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Heart Attack ◽  
Total Content ◽  
Reactive Component ◽  
Mature Leaves ◽  
Maturity Stages ◽  
Sonneratia Caseolaris ◽  
Young Leaves ◽  
Ic50 Values

Free radical is a reactive component because it has one or more electrons. Free radical is very dangerous for our body because it can cause degenerative diseases, such as cancer, heart attack, and aging. Cancer and heart attack are one of the most killer disease. All we can do to decrease the free radical effect is consume antioxidant. S. caseolaris leaves has antioxidant activity, but it has known yet which stage of maturity is the best one for produce the highest antioxidant activity. This purpose of this research is knowing the influence between maturity and antioxidant activity at different maturity stages. This method of this research is experimental with Completely Randomized Design. The treatment in this research is vitamin C, fresh leaves in ethanol 96% extract, young leaves in ethanol 96% extract, and mature leaves in ethanol 96% extract. The main parameter of this research is IC50 values and the secondary parameters are total content of phytochemical in every extract. Data analysis using descriptive method with 4 treatments and five replications. The result of this research show that the maturity has influence in antioxidant activity. Inhibitory concentration 50 (IC50) values of shoot leaves extract, young leaves extract and mature leaves extract is 12.0013 ppm, 13.9915 ppm and 14.6613 ppm. All of them are called antioxidant which has very strong activities. The highest phytochemical compound is found on shoot leaves extract with ethanol 96% solvent.

scholarly journals Effect of kinetin on nucleic acid synthesis in senescing and young leaves in Brassica oleracea L. var. gongylodes L.

2015 ◽  
Vol 44 (4) ◽  
pp. 553-565
Author(s):  
J. Legocka ◽  
A. Szweykowska
Keyword(s):  
Molecular Weight ◽  
Nucleic Acid ◽  
Acid Synthesis ◽  
Inhibitory Effect ◽  
Rrna Synthesis ◽  
Low Molecular Weight ◽  
Chlorophyll B ◽  
Mature Leaves ◽  
Young Leaves ◽  
Brassica Oleracea L

In detached kohlrabi leaves senescing in the dark, the decrease in chlorophyll to was more pronounced than in chlorophyll a. The retardation by kinetin of the chlorophyll loss was also markedly stronger in the case of chlorophyll b. Using the fractionation of nucleic acids on polyacrylamide gels it has been shown that during leaf senescence the level of all RNA species decreased, whereas the amount of DNA was more or less constant. In the presence of kinetin, the loss of RNA was inhibited and the incorporation of precursor into the cytoplasmic rRNA as well as into low molecular weight RNA species was supported. Chloroplast rRNA synthesis has not been detected in mature leaves and kinetin showed no effect in this respect. In young expanding leaves detached and kept in light, the synthesis of cytoplasmic rRNA was strongly stimulated by kinetin, whereas in the case of Chloroplast rRNA only an inhibitory effect of kinetin could be found. The results suggest that the cytokinins are primarily involved in processes of the synthesis of cytoplasmic rRNA and low molecular RNA fractions, and in this way affect the development of plastids, in particular the course of their senescence.

A new endangered species of Psidium (Myrtaceae, Myrteae) from Bahia, Brazil

Phytotaxa ◽  
2016 ◽  
Vol 288 (2) ◽  
pp. 161 ◽  
Author(s):  
AMÉLIA CARLOS TULER ◽  
ARIANE LUNA PEIXOTO ◽  
CAROLYN E.B. PROENÇA
Keyword(s):  
Endangered Species ◽  
Atlantic Forest ◽  
21St Century ◽  
Deciduous Forests ◽  
Northeastern Brazil ◽  
Distribution Map ◽  
Small Tree ◽  
Early 21St Century ◽  
Mature Leaves ◽  
Young Leaves

This paper describes a new, very distinctive, endangered species of Psidium (Myrtaceae, Myrteae) occurring in Bahia in Northeastern Brazil, in the Diamantina Atlantic Forest center of endemism, considered in the Atlantic Forest domain although transitional with the Caatinga domain. It is a small tree up to 5m tall. The species, that we have named Psidium rotundidiscum, is promptly recognized by the combination of petioles 4–7mm long, young leaves that are densely ferrugineous pubescent, spathulate and strongly revolute and mature leaves that are glabrescent, revolute, with an inconspicuous venation. The inflorescences are terminal precocious (auxotelic) racemes with 1–2 pairs of flowers or solitary flowers on new growth. Floral buds are nearly closed, ca. 7–10mm long and densely ferruginous pubescent; specimens with open flowers are unknown. The oblate fruits, with a rounded disk with relatively few staminal scars and rather thick, explanate calyx lobes are also distinctive. The species is known from only three late 20th/early 21st century collections from deciduous forests, semi-deciduous forests, liana forests and xerophytic forests along a North to South extension of ca. 700 km in inland Bahia. Images of collections in bud and in fruit are furnished as well as a geographic distribution map.

scholarly journals Detection and identification of a novel 16SrXIII subgroup phytoplasma associated with strawberry red leaf disease in Argentina

2015 ◽  
Vol 65 (Pt_8) ◽  
pp. 2741-2747 ◽  
Author(s):  
Franco D. Fernández ◽  
Natalia G. Meneguzzi ◽  
Fabiana A. Guzmán ◽  
Daniel S. Kirschbaum ◽  
Vilma C. Conci ◽  
...  
Keyword(s):  
Rflp Analysis ◽  
Rrna Gene ◽  
The Novel ◽  
Universal Primer ◽  
Mature Leaves ◽  
Leaf Disease ◽  
Detection And Identification ◽  
Rflp Profile ◽  
Young Leaves ◽  
Leaf Symptoms

Strawberry red leaf phytoplasma was found in strawberry plants from production fields in Lules (Tucumán province) and Bella Vista (Corrientes province), Argentina. Characteristic strawberry red leaf symptoms were stunting, young leaves with yellowing at the edges, mature leaves which curled and were reddish at the abaxial face, flower and fruit deformation and death. The pathogen was detected with phytoplasma-universal primer pairs P1/P7 followed by R16F2n/R16R2 as nested primers in 13 diseased plants. Based on RFLP and sequence analysis of the amplified 16S rRNA gene, the phytoplasma was related to the 16SrXIII group (Mexican periwinkle virescence). In silico the RFLP profile of all the samples analysed revealed the presence of a unique pattern, showing that the novel phytoplasma is different from all the phytoplasmas currently composing the 16SrXIII group. The phylogenetic analysis was consistent with RFLP analysis as the strawberry red leaf phytoplasma was grouped within the 16SrXIII group, but formed a particular cluster. On this basis, the Strawberry red leaf phytoplasma associated with strawberry red leaf disease was assigned to a new subgroup, 16SrXIII-F.

Osmotic Adjustment: Effect of Water Stress on Carbohydrates in Leaves, Stems and Roots of Apple

1995 ◽  
Vol 22 (5) ◽  
pp. 747 ◽  
Author(s):  
Z Wang ◽  
B Quebedeaux ◽  
GW Stutte
Keyword(s):  
Water Stress ◽  
Osmotic Adjustment ◽  
Sucrose Concentration ◽  
Starch Content ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
Malus Domestica Borkh ◽  
Mature Leaves ◽  
Young Leaves ◽  
Response To Water

Potted apple (Malus domestica Borkh. cv. Jonathan) trees were subjected to water stress in a greenhouse. Midday leaf water potential (ΨW), osmotic potential (ΨS), soluble carbohydrates, and starch content of expanding and mature leaves, stems, and roots were measured to determine whether active osmotic adjustment occurred and if water stress affected carbohydrate metabolism. Mature leaves had the highest total soluble carbohydrate level (357 mM) and lowest Ψ (-1.85 MPa), followed by young leaves (278 mM, -1.58 MPa), stems (115 mM, -1.02 MPa), and roots (114 mM, -0.87 MPa). Sorbitol was the major component in all organs ranging from 53% of total soluble carbohydrate in young leaves to 73% in mature leaves. When ΨW decreased from -1.0 to -3.2 MPa, active osmotic adjustments of 0.3-0.4 MPa were observed in mature leaves, stems, and roots while a significantly higher adjustment of 1.0 MPa was detected in young leaves 5 days after the initiation of water stress. Sorbitol levels in leaves and stems gradually increased as ΨW decreased from -1.0 to -2.5 MPa, and then remained relatively stable or decreased slightly as ΨW decreased from -2.5 to -3.2 MPa. However, the percentage of soluble carbohydrate as sorbitol in roots decreased in response to water stress. Sucrose concentration decreased in mature leaves and stems, but increased in young leaves and roots as ΨW decreased. Starch concentrations in stems and roots also decreased as water stress developed. The sorbitol to sucrose ratios increased in mature leaves, but decreased in roots in response to water stress.

scholarly journals Differential responses between mature and young leaves of sunflower plants to oxidative stress caused by water deficit

2010 ◽  
Vol 40 (6) ◽  
pp. 1290-1294 ◽  
Author(s):  
Inês Cechin ◽  
Natália Corniani ◽  
Terezinha de Fátima Fumis ◽  
Ana Catarina Cataneo
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Intercellular Co2 Concentration ◽  
Leaf Age ◽  
Co2 Concentration ◽  
Mature Leaves ◽  
Young Leaves ◽  
Mda Content ◽  
Gas Exchange Characteristics

The effects of water stress and rehydration on leaf gas exchange characteristics along with changes in lipid peroxidation and pirogalol peroxidase (PG-POD) were studied in mature and in young leaves of sunflower (Helianthus annuus L.), which were grown in a greenhouse. Water stress reduced photosynthesis (Pn), stomatal conductance (g s), and transpiration (E) in both young and mature leaves. However, the amplitude of the reduction was dependent on leaf age. The intercellular CO2 concentration (Ci) was increased in mature leaves but it was not altered in young leaves. Instantaneous water use efficiency (WUE) in mature stressed leaves was reduced when compared to control leaves while in young stressed leaves it was maintained to the same level as the control. After 24h of rehydration, most of the parameters related to gas exchange recovered to the same level as the unstressed plants except gs and E in mature leaves. Water stress did not activated PG-POD independently of leaf age. However, after rehydration the enzyme activity was increased in mature leaves and remained to the same as the control in young leaves. Malondialdehyde (MDA) content was increased by water stress in both mature and young leaves. The results suggest that young leaves are more susceptible to water stress in terms of gas exchange characteristics than mature leaves although both went through oxidative estresse.

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