Plant leaves are studied by the analysis of the magnitude and phase spectra of their thickness mechanical resonances. These resonances appear at ultrasonic frequencies and have been excited and sensed using air-coupled ultrasounds. In spite of the complex leaf microstructure, the effective medium approach can be applied to solve the inverse problem, at least in the vicinity of the first thickne...

The Plant Vigor Hypothesis (PVH) predicts an oviposition preference of females and higher offspring performance for insect herbivores on longer and fast-growing plant modules. We tested the PVH predictions by investigating the effects of leaf size of Miconia prasina (Sw.) DC. (Melastomataceae) on the oviposition preference and on the offspring survival of the gall-inducing weevil Prospoliata bi...

Agrobacterium tumefaciens causes crown gall disease on a variety of plants. During the infection process Agrobacterium transfers a nucleoprotein complex, the VirD2 T-complex, and at least two Vir proteins, VirE2 and VirF, into the plant cell via the VirB/VirD4 type IV secretion system. Recently, we found that T-DNA could also be transferred from Agrobacterium to Saccharomyces cerevisiae. Here, ...

BACKGROUND Agrobacterium vitis is a causal agent of crown-gall disease. Trifolitoxin (TFX) is a peptide antibiotic active only against members of a specific group of alpha-proteobacteria that includes Agrobacterium and its close relatives. The ability of TFX production by an avirulent strain of Agrobacterium to reduce crown gall disease is examined here. RESULTS TFX was shown to be inhibitory...

Three major hypotheses have been advanced for the adaptive nature of plant galls: nutrition, enemyavoidance, and microenvironment. Of these, the microenvironment hypothesis has been frequently invoked, but rarely tested directly. We tested this hypothesis in a population of Andricus quercuscalifornicus (Bassett) (Hymenoptera: Cynipidae) wasps inducing galls on Quercus lobata Née (Fagaceae) tree...

The relations between a large number of scientific subdisciplines within the population biology of plants are presented. This overview in which the holistic and reductionistic approaches are discussed, emphasizes that conflicts between both attitudes are artificially raised. In fact, the one approach must support the other in order to trace the relations between the individual plants and their ...

Various bioactive compounds possessing the properties as antioxidant, antibacterial, antifungal, antimutagenic and anticancerous have been characterized and isolated from different parts of plants. Some studies in recent years have reported the occurrence of such bioactive compounds in pollen grains as well. Considering this, the present study was planned to examine antitumor activities of etha...

Crops can be devastated by pathogenic strains of Agrobacterium tumefaciens that cause crown gall tumors. This devastation can be prevented by the nonpathogenic biocontrol agent A. radiobacter K84, which prevents disease by production of the "Trojan horse" toxin agrocin 84, which is specifically imported into tumorgenic A. tumefaciens strains to cause cell death. We demonstrate that this biocont...

  Background: Tumors involving the hand skeleton are rare. However, a basic knowledge of hand tumors is necessary for every clinician. This is due to the importance of distinguishing typical benign tumors from life or limb threatening malignant ones. Methods: This study is a review of 99 cases of osseous hand tumors presented to the department of orthopedic surgery, Imam Khomeini Hospital in Te...

background gastrointestinal stromal tumors (gists) are potentially malignant tumors; however their behavior and response to treatment is dependent on the type of mutation and immunohistochemical expression of antigens. it is recommended to perform routine molecular and immunohistochemical tests in kit and platelet derived growth factor receptor alpha (pdgfra) molecules for making decision regar...