The Mechanical Feedback Theory of Leaf Lamina Formation

2020 ◽  
Author(s):  
Yuling Jiao ◽  
Fei Du ◽  
Jan Traas
Keyword(s):  
Leaf Lamina ◽  
Mechanical Feedback

Effect of light intensity on assimilation characteristics of detached tea leaves

1964 ◽  
Vol 63 (2) ◽  
pp. 265-271 ◽  
Author(s):  
D. N. Barua
Keyword(s):  
Light Intensity ◽  
Chlorophyll Concentration ◽  
Leaf Lamina ◽  
Tea Leaves ◽  
Tungsten Filament ◽  
Strong Light ◽  
Filament Lamp ◽  
Sun Leaves ◽  
Different Sources ◽  
Effect Of Light

Photosynthetic rates of detached, mature tea leaves from four different sources were determined in excess CO2 and light of 4, 10, 16 and 32 klux intensities from a tungsten-filament lamp. Temperature was maintained at 25°C. The assimilation rates were significantly different for the four sources both in weak and in strong light. Neither thickness of the leaf lamina nor chlorophyll concentration could explain the cause of this difference.The effect of shade adaptation on the subsequent rate of assimilation was examined in one of the four sources of leaf. Shade-adapted leaves had significantly higher rates of photosynthesis at the weakest light intensity of 4 klux and lower rates in 16 and 32 klux intensities than the corresponding sun leaves.

scholarly journals The Crossroads between RAS and RHO Signaling Pathways in Cellular Transformation, Motility and Contraction

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 819
Author(s):  
Olga Soriano ◽  
Marta Alcón-Pérez ◽  
Miguel Vicente-Manzanares ◽  
Esther Castellano
Keyword(s):  
Signaling Pathways ◽  
Actin Polymerization ◽  
Mapk Pathway ◽  
Human Cancer ◽  
Cellular Transformation ◽  
Dependent Manner ◽  
Rho Proteins ◽  
Filament Assembly ◽  
Multiple Signaling ◽  
Mechanical Feedback

Ras and Rho proteins are GTP-regulated molecular switches that control multiple signaling pathways in eukaryotic cells. Ras was among the first identified oncogenes, and it appears mutated in many forms of human cancer. It mainly promotes proliferation and survival through the MAPK pathway and the PI3K/AKT pathways, respectively. However, the myriad proteins close to the plasma membrane that activate or inhibit Ras make it a major regulator of many apparently unrelated pathways. On the other hand, Rho is weakly oncogenic by itself, but it critically regulates microfilament dynamics; that is, actin polymerization, disassembly and contraction. Polymerization is driven mainly by the Arp2/3 complex and formins, whereas contraction depends on myosin mini-filament assembly and activity. These two pathways intersect at numerous points: from Ras-dependent triggering of Rho activators, some of which act through PI3K, to mechanical feedback driven by actomyosin action. Here, we describe the main points of connection between the Ras and Rho pathways as they coordinately drive oncogenic transformation. We emphasize the biochemical crosstalk that drives actomyosin contraction driven by Ras in a Rho-dependent manner. We also describe possible routes of mechanical feedback through which myosin II activation may control Ras/Rho activation.

Puccinia levis var. brachiariae. [Descriptions of Fungi and Bacteria].

2009 ◽  
Author(s):  
P. F. Cannon
Keyword(s):  
Host Plant ◽  
Geographical Distribution ◽  
Conservation Status ◽  
Leaf Lamina ◽  
Brachiaria Brizantha ◽  
Urochloa Decumbens ◽  
Urochloa Brizantha

Abstract A description is provided for Puccinia levis var. brachiariae comb. nov., which causes small lesions on young stems and leaf lamina of the host plant and, where present in quantity, could significantly reduce vigour. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (Malawi, Uganda, Zambia and Brazil) and hosts (Brachiaria brizantha [Urochloa brizantha], B. decumbens [Urochloa decumbens], B. humidicola [Urochloa humidicola] and an unnamed Brachiaria sp.).

Two new endemic species of Caraipa (Calophyllaceae) from the Central Amazon Basin, Amazonas State, Brazil

Phytotaxa ◽  
2017 ◽  
Vol 311 (1) ◽  
pp. 77
Author(s):  
FERNANDA NUNES CABRAL ◽  
VOLKER BITTRICH ◽  
MARIA DO CARMO ESTANISLAU DO AMARAL
Keyword(s):  
New Species ◽  
Endemic Species ◽  
Amazon Basin ◽  
Leaf Lamina ◽  
Small Tree ◽  
Central Amazon ◽  
White Sand ◽  
Two New Species ◽  
Amazonas State ◽  
Fruit Surface

Two new species of Caraipa (Calophyllaceae) are described and illustrated: Caraipa glabra and C. iracemensis. Both species are known only from the municipality of Presidente Figueiredo, Amazonas state, Brazil. They both occur on patches of white-sand vegetation and they are locally abundant. Caraipa glabra is a small tree and can be distinguished from other Caraipa species by the complete absence of hairs on the leaf lamina, pedicel and fruits. Caraipa iracemensis is morphologically similar to C. grandifolia and C. caespitosa, and can be distinguished by its habit, leaves and petiole size, as well as fruit surface and size.

scholarly journals Biological and serological characterization of viruses of summer squash crops in Yugoslavia

2002 ◽  
Vol 47 (2) ◽  
pp. 149-160 ◽  
Author(s):  
Natasa Dukic ◽  
Branka Krstic ◽  
Ivana Vico ◽  
N.I. Katis ◽  
Chryssa Papavassiliou ◽  
...  
Keyword(s):  
Aphis Gossypii ◽  
Virus Transmission ◽  
Leaf Lamina ◽  
Serological Characterization ◽  
Summer Squash ◽  
Leaf Yellowing ◽  
Prevalent Virus ◽  
Viral Nature

A survey on summer squash open field crops was carried out during 2000 and 2001 in order to identify the major viruses infecting these crops in different localities. Plants showed different types of symptoms: mild mosaic, chlorotic spotting, distinctive mosaic, blistering of leaf lamina leaf yellowing, deformation of leaf lamina, knobbed fruits and stunting of plants. The symptoms were very variable but showed the viral nature of the investigated summer squash diseases. The collected samples were tested by bioassay and by two serological methods ELISA and EBIA using cucumber mosaic cucumovirus (CMV), zucchini yellow mosaic potyvirus (ZYMV), watermelon mosaic potyvirus 2 (WMV-2), zucchini yellow flack potyvirus (ZYFV) watermelon mosaic potyvirus 1 (WMV-1), squash mosaic comovirus (SqMV) and cucurbit aphid-borne yellows polerovirus (CABYV) polyclonal antisera. In all tested samples single or mixed infection with ZYMV, CMV and WMV-2 was detected. The most prevalent virus infecting summer squash was ZYMV. This is the first report of ZYMV, the most destructive virus infecting cucurbits, in Yugoslavia. It was also proven that the identified viruses are transmissible by Aphis gossypii in a non-persistent manner, but possible role of seed in virus transmission was not confirmed.

scholarly journals Role of the beet western yellows virus readthrough protein in virus movement in Nicotiana clevelandii

1999 ◽  
Vol 80 (10) ◽  
pp. 2771-2778 ◽  
Author(s):  
J. D. Mutterer ◽  
C. Stussi-Garaud ◽  
P. Michler ◽  
K. E. Richards ◽  
G. Jonard ◽  
...  
Keyword(s):  
Virus Multiplication ◽  
Virus Movement ◽  
Wild Type ◽  
Leaf Lamina ◽  
Thin Sections ◽  
Beet Western Yellows Virus ◽  
Whole Plants ◽  
Readthrough Protein ◽  
Nicotiana Clevelandii

Luteoviruses such as beet western yellows polerovirus (BWYV) are confined to and multiply within the phloem compartment of their hosts. The readthrough domain (RTD) of the minor BWYV capsid protein P74 is required for efficient virus accumulation in Nicotiana clevelandii. Experiments were carried out to determine if the low virus titres observed following agro-inoculation of whole plants with certain RTD mutants are due to a defect in virus multiplication in the nucleate cells of the phloem compartment or to inefficient virus movement to new infection sites. Immuno-localization of wild-type and an RTD-null mutant virus in thin sections of petioles and in phloem cells of leaf lamina, as well as electron microscopy observations, were all consistent with the conclusion that the RTD is not essential for efficient virus multiplication in the nucleate phloem cells but intervenes in virus movement to increase the rate at which new infection foci are established and expand.

scholarly journals Dicranum ignatovii sp. nova (Dicranaceae, Bryophyta) from the Far East

2018 ◽  
Vol 12 (1) ◽  
Keyword(s):  
Phylogenetic Analysis ◽  
New Species ◽  
Far East ◽  
Integrative Taxonomy ◽  
Rrna Gene ◽  
Unique Combination ◽  
Leaf Lamina ◽  
Kurile Islands ◽  
The Far East ◽  
Molecular Phylogenetic

The new species Dicranum ignatovii Tubanova & Fedosov is described from Sakhalin, South Kurile Islands and the Khabarovsk Territory based on the approach of integrative taxonomy. The species is characterized by the unique combination of (1) short leaves with broadly acute apex, (2) slightly recurved distal leaf lamina, (3) short-rectangular to transverse rectangular distal leaf cells, (4) proximal leaf cells abruptly shortened distally and thus occupying only the basalmost leaf portion, (5) costa ending before apex, and (6) presence of flagelliform branchlets in upper leaf axils. Based on nrITS 1, 2 & 5.8 rRNA gene sequences, molecular phylogenetic analysis was carried out. As a result, three studied specimens were found in a well supported clade, nested in a weakly supported clade where D. acutifolium, D. caesium, D. bardunovii, D. angustum, D. bonjeanii, D. scoparium and D. brevifolium were also found.

scholarly journals The statistics of noisy growth with mechanical feedback in elastic tissues

2018 ◽  
Author(s):  
Ojan Khatib Damavandi ◽  
David K. Lubensky
Keyword(s):  
Tissue Growth ◽  
Fundamental Aspect ◽  
Isotropic Case ◽  
Anisotropic Growth ◽  
Clone Size ◽  
Density Correlation ◽  
Precise Control ◽  
Growth Modes ◽  
Elastic Sheets ◽  
Mechanical Feedback

Tissue growth is a fundamental aspect of development and is intrinsically noisy. Stochasticity has important implications for morphogenesis, precise control of organ size, and regulation of tissue composition and heterogeneity. Yet, the basic statistical properties of growing tissues, particularly when growth induces mechanical stresses that can in turn affect growth rates, have received little attention. Here, we study the noisy growth of elastic sheets subject to mechanical feedback. Considering both isotropic and anisotropic growth, we find that the density-density correlation function shows power law scaling. We also consider the dynamics of marked, neutral clones of cells. We find that the areas (but not the shapes) of two clones are always statistically independent, even when they are adjacent. For anisotropic growth, we show that clone size variance scales like the average area squared and that the mode amplitudes characterizing clone shape show a slow 1/n decay, where n is the mode index. This is in stark contrast to the isotropic case, where relative variations in clone size and shape vanish at long times. The high variability in clone statistics observed in anisotropic growth is due to the presence of two soft modes—growth modes that generate no stress. Our results lay the groundwork for more in-depth explorations of the properties of noisy tissue growth in specific biological contexts.

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