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81.
Simcha Lev-Yadun 《Plant signaling & behavior》2009,4(6):482-483
Müllerian mimicry is common in aposematic animals but till recently, like other aspects of plant aposematism was almost unknown. Many thorny, spiny and prickly plants are considered aposematic because their sharp defensive structures are colorful and conspicuous. Many of these spiny plant species (e.g., cacti and Agave in North American deserts; Aloe, Euphorbia and acacias with white thorns in Africa; spiny plants in Ohio; and spiny members of the Asteraceae in the Mediterranean basin) have overlapping territories, and also similar patterns of conspicuous coloration, and suffer from the evolutionary pressure of grazing by the same large herbivores. I propose that many of these species form Müllerian mimicry rings.Key words: aposematic coloration, defense, evolution, herbivory, müllerian mimicry, spines, thornsAposematic (warning) coloration is a biological phenomenon in which poisonous, dangerous or otherwise unpalatable organisms visually advertise these qualities to other animals. The evolution of aposematic coloration is based on the ability of target enemies to associate the visual signal with the risk, damage or non-profitable handling, and later to avoid such organisms as prey. Typical colors of aposematic animals are yellow, orange, red, purple, black, white or brown and combinations of these.1–5 Many thorny, spiny and prickly plant species were proposed to be aposematic because their sharp defensive structures are usually colorful (yellow, orange, red, brown, black, white) and/or associated with similar conspicuous coloration.5–22 Animal spines also have similar conspicuous coloration and were proposed to be aposematic.1,5,17,23Several authors have proposed that mimicry of various types helps in plant defense, e.g.,9,24–34 More specifically, Müllerian mimicry was already proposed to exist in several defensive plant signaling systems. The first was for several spiny species with white-variegated leaves.8,10 The second was for some tree species with red or yellow poisonous autumn leaves.35 The third cases are of a mixture of Müllerian and Batesian mimicry, of thorn auto-mimicry found in many Agave species.8Here I propose that many species of visually aposematic spiny plants of the following taxa: (1) Cactaceae, (2) the genus Agave, (3) the genus Aloe, (4) African thorny members of the genus Euphorbia, (5) African acacias with white thorns, (6) spiny vascular plants of southeastern Ohio, (7) spiny Near Eastern plants with white variegation on their leaves, (8) Near Eastern members of the Asteraceae with yellow spines, form Müllerian mimicry rings of spiny plants.To consider the existence of Müllerian mimicry rings in aposematic organisms, two factors are needed: (1) a similar signal, and (2) an overlapping distribution in respect to the territory of predators in animals, or herbivores in plants. I will show below that for the plant taxa proposed here to form Müllerian mimicry rings, both criteria operate.The accumulating data about the common association of plant defenses by spines with visual conspicuousness, along with the fact that many such species overlap in their habitat, raises the possibility of the broad phenomenon of existence of Müllerian mimicry rings in plants. Even from the limited number of publications proposing visual aposematism in spiny plants, the operation of vegetal Müllerian mimicry rings seems to be obvious. The phenomenon can now be traced to both the Old World (Asia, Africa and Europe) and the New World (North America). The best-studied cases include Cactaceae and the genera Agave, Aloe and Euphorbia,6 African acacias with white thorns,12,15 Near Eastern spiny plants with white variegation on their leaves,7,11 aposematic spiny vascular plants of southeastern Ohio,16 and many spiny Mediterranean species of the Asteraceae with yellow spines.22In the four spiny taxa (Cactaceae and the genera Agave, Aloe and Euphorbia) that were the first to be proposed as visually aposematic6 there is a very strong morphological similarity. In cacti, there are two types of conspicuousness of spines that are typical of many plant species: (1) colorful spines, and (2) white spots, or white or colorful stripes, associated with spines on the stems. These two types of aposematic coloration also dominate the spine system of Agave, Aloe and Euphorbia. The fact that many species of three of these four spiny taxa (Agave, Aloe and Euphorbia) are also poisonous36–38 further indicates their potential to form Müllerian mimicry rings.I propose that each of these groups for itself and some of these groups (e.g., Cactaceae and the genus Agave in North America; Aloe, Euphorbia and acacias in east and south Africa) that have overlapping distribution and share at least some of the herbivores, form Müllerian mimicry rings.The first Müllerian mimicry ring is of cacti and Agave that have an overlapping distribution over large areas in North America.37,39 The large herbivores in North America disappeared not so long ago in evolutionary time scales and seem to have shaped the spiny defense of these plant taxa.40The second Müllerian mimicry ring is of the spiny and thorny members of the African genera Aloe, Euphorbia and certain acacias with very conspicuous white thorns, which partly overlap in distribution and share various large mammalian herbivores.12,15,36,41The third Müllerian mimicry ring is the outcome of the common presence of aposematic coloration in spiny vascular plants of southeastern Ohio,16 with color patterns in thorns and spines similar to those of Cactaceae and the genera Agave, Aloe and Euphorbia described in Lev-Yadun.6The next case of potential operation of Müllerian mimicry ring of spiny plants with overlapping territories that suffer from the same large herbivores, but on a much smaller geographical scale, has recently been proposed for several spiny species with white-variegated leaves,7 and later for more than 20 spiny species in the flora of Israel that have white markings associated with their spines.11The last case of a probable Müllerian mimicry ring was described by Ronel et al.22 who while studying the spine system of Near Eastern spiny members of the Asteraceae, found 29 spiny species with yellow spines, and additional such species are expected to occur. Since some of these species and others with yellow spines also grow in southern Europe, it is clear that the same phenomenon is also common there.I conclude that Müllerian mimicry rings seem to be very common in plants, and that it is probable that many other spiny plants that form Müllerian mimicry rings are waiting to be studied. Such defensive rings are probably also formed by poisonous plants that share similar colors or odors. 相似文献
82.
Michaeli A Finci-Yeheskel Z Dishon S Linke RP Levin M Urieli-Shoval S 《Biochemical and biophysical research communications》2008,368(2):368-373
We have recently reported that the acute phase protein serum amyloid A (SAA), is locally and differentially expressed in neoplastic tissues of human colon. In the present study, we demonstrate that SAA enhances the plasminogen activation (PA)-activity of HT-29 colon cancer cell line. Cell-associated PA-activity was measured following the plasminogen-dependent ability of the cells to cleave the chromogenic substrate S-2251. The SAA-enhanced PA-activity was inhibited by anti-SAA antibodies. These antibodies also decreased the basal PA-activity of HT-29 cells and neutralized their cytokines (Interleukin-1β + Interleukin-6)—enhanced PA-activity. Using specific chromogenic substrates and the fibrin clot-lysis assay, we found that SAA enhances also the PA-activity mediated by purified urokinase- and tissue-type plasminogen activators. Together, the data indicate that SAA enhances plasminogen activation and suggest its possible role in plasmin(ogen)-mediated colon cancer progression. 相似文献
83.
<Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> as a Model System for Graft Union Development in Homografts and Heterografts 总被引:1,自引:0,他引:1
Moshe A. Flaishman Kamelia Loginovsky Sara Golobowich Simcha Lev-Yadun 《Journal of Plant Growth Regulation》2008,27(3):231-239
Homografting of Arabidopsis
thaliana scions on stocks of A.
thaliana and heterografting on other species were used to study the compatibility and the ontogeny of graft union formation. Highly compatible homografting with scions of young leafy inflorescence stems was obtained on stocks of inflorescence stems
growing from large 3-month-old A.
thaliana plants. Histologic analysis revealed four developmental stages of graft union formation in Arabidopsis homografting: (1) development of a necrotic layer, (2) callus proliferation in the grafted scion, (3) differentiation of
new vascular tissues within the scion, and (4) a full vascular graft union formation between the scion and the stock. Vascular
connections were formed within the callus bridge between rootstocks and scions 15 days after grafting. Heterografts of Arabidopsis on two members of Brassicaceae, cabbage (Brassica) and radish (Raphanus), showed partial incompatible interaction with a lower level of vascular differentiation. Arabidopsis grafting on tomato (Solanaceae) rootstock showed complete incompatibility and limited noncontinuous differentiation of new
vascular tissues that did not cross the scion/stock boundary. Although lacking scion/stock vascular connections, Arabidopsis scions grafted onto tomato rootstock flowered and produced seeds. This may indicate some nonvascular functional connections
between the two plants, probably of parenchyma cells, further emphasizing the usefulness of Arabidopsis as a model plant for studying various levels of the complicated scion/stock relationships expressed in grafting biology.
Experiments with dye transport in the xylem showed that although in general there was an agreement between the histologic
study and dye transport, in Arabidopsis homografts water transport frequency was lower than functional and histologic compatability. We conclude that homografting
and heterografting of Arabidopsis inflorescence stems is a convenient and reproducible method for studying the fundamental cellular genetic and molecular aspects
of grafting biology. 相似文献
84.
85.
86.
87.
Hammerman H Isserles S Milo S 《International journal of cardiovascular interventions》1999,2(4):253-255
We describe a patient following acute myocardial infarction with a protracted clinical course presenting transient episodes of hypotension, who eventually developed cardiac tamponade. Echocardiography demonstrated pericardial effusion and emergency pericardiocentesis revealed blood. The patient's condition was stabilized and she underwent emergency thoracotomy with successful repair of left ventricular rupture. We discuss the literature and suggest an approach for management of patients with suspected ventricular rupture after myocardial infarction. 相似文献
88.
Summary The early-formed xylem of Suaeda monoica Forssk. ex J. F. Gmel (Chenopodiaceae) is temporarily rayless. Vascular rays differentiate during later stages of its xylem ontogeny. The rays in Suaeda are heterogeneous, and some of them are aggregated. The mature xylem of this species is characterized by two unique types of vascular rays: (1) rays with several inside initiation centres of small cells formed by local frequent cell divisions in the cambium, and (2) huge xylem rays with radial phloem strands that are connected to the axial phloem. The spacing of the xylem rays is not even, and possible mechanisms controlling ray spacing are discussed. Our observations indicate that rays do not have an inhibitory zone around them in which ray initiation is prevented. The initiation of radial patterns of small cells which appear like inside rays within a large vascular ray suggests that initiation and spacing of rays is controlled by radial signal flows in relationship with axial signal fluxes. 相似文献
89.
90.
Simcha?Lev-YadunEmail author Sarah?E.?Wyatt Moshe?A.?Flaishman 《Journal of Plant Growth Regulation》2004,23(4):301-306
Arabidopsis thaliana is gradually gaining significance as a model for wood and fiber formation.revolute/ifl1 is an important mutant in this respect. To better characterize the fiber system of therevolute/ifl1 mutant, we grew plants of two alleles (rev-9 in Israel andrev-1 in the USA) and examined the fiber system of the inflorescence stems using both brightfield and polarized light. Microscopic
examination of sections of plants belonging to the two different alleles clearly revealed that, contrary to previous views,
in 18 (13 in Israel and 5 in Ohio) out of 30 stems (20 in Israel and 10 in Ohio) the mutant produced the primary wavy fiber
system of the inflorescence stems. Our findings are further supported by the fact that fibers are seen in the figures published
in other studies of the mutant even when it was stated that there were no fibers. The impression of a total lack of the wavy
band of fibers is in many cases just a result of poorly lignified secondary walls. This specific gene that reduces lignification
in fibers is of great significance for biotechnological developments for the paper industry and thus for the global economy
and ecology. We propose thatrevoluta, the first name given to this mutant (Talbert and others 1995), is more appropriate thanifl1.
Online publication: 7 April 2005 相似文献