Molecular mechanism of the juvenile hormone action.

Structures, physiological role and level regulation of the juvenile hormones are described. A scheme of juvenile hormone mode of action at the molecular level, which includes transport of hormone via its binding protein, is presented.     

Immunosuppressory activity of the cyclodimeric peptide with RGD-sequences.

Our previous studies showed that the nonapeptide fragment of HLA-DQ of the sequence H-Thr-Pro-Gln-Arg-Gly-Asp-Val-Tyr-Thr-OH, located in the beta164-172 loop, strongly suppresses the humoral and cellular immune responses, while its shorter analogs, H-Arg-Gly-Asp-Val-OH, H-Arg-Gly-Asp-Val-Tyr-OH and H-Gln-Arg-Gly-Asp-Val-Tyr-OH show only a weak stimulatory activity in respect to the humoral immunological response. These fragments contain the Arg-Gly-Asp (RGD) sequence, known for its importance for cellular association phenomena. Based on the crystal structure of HLA-DR1, we also designed and synthesized a cyclic analog H-Cys-Arg-Gly-Asp-Val-Tyr-Cys-OH with restricted conformation, which strongly suppresses the immune response and selectively inhibits the alphavbeta3 integrin, suggesting that the mechanism of the immunosuppressory action of the peptide is associated with inhibition of the integrin. In this paper we present the design and synthesis of the cyclodimeric peptide, Arg-Gly-Asp-Arg-Gly-Asp, which is also known as a selective alphavbeta3 inhibitor. The synthesized peptide strongly suppresses both the humoral and cellular immune response. The results support our hypothesis that the immunomodulatory activity of HLA-DQ fragments may be connected with their interactions with some particular integrins on the cell surface.     

The Role of MPK6 as Mediator of Ethylene/Jasmonic Acid Signaling in <Emphasis Type="Italic">Serendipita indica</Emphasis>-Colonized Arabidopsis Roots

Serendipita indica is an axenically cultivable fungus, which colonizes a broad range of plant species including the model plant Arabidopsis thaliana. Root colonization by this endophyte leads to enhanced plant fitness and performance and promotes resistance against different biotic and abiotic stresses. The involvement of MPK6 in this mutualistic interaction had been previously shown with an mpk6 A. thaliana mutant, which failed to respond to S. indica colonization. Here, we demonstrate that mpk6 roots are significantly less colonized by S. indica compared to wild-type roots and the foliar application of plant hormones, ethylene, or jasmonic acid, restores the colonization rate at least to the wild-type level. Further, hormone-treated mpk6 plants show typical S. indica-induced growth promotion effects. Moreover, expression levels of several genes related to plant defense and hormone signaling are significantly changed at different colonization phases. Our results demonstrate that the successful root colonization by S. indica depends on efficient suppression of plant immune responses. In A. thaliana, this process relies on intact hormone signaling in which MPK6 seems to play a pivotal role.     

Alterations of the portal protein,gpB, of bacteriophage lambda suppress mutations in cosQ,the site required for termination of DNA packaging

The cosQ site of bacteriophage lambda is required for DNA packaging termination. Previous studies have shown that cosQ mutations can be suppressed in three ways: by a local suppressor within cosQ, an increase in the length of the lambda chromosome, and missense mutations affecting the prohead's portal protein, gpB. In the present work, revertants of a set of lethal cosQ mutants were screened for suppressors. Seven new cosQ suppressors affected gene B, which encodes the portal protein of the prohead. All seven were allele-nonspecific suppressors of cosQ mutations. Experiments with several phages having two cosQ suppressors showed that the suppression effects were additive. Furthermore, these double suppressors had minimal effects on the growth of cosQ(+) phages. These trans-acting suppressors affecting the portal protein are proposed to allow the mutant cosQ site to be more efficiently recognized, due to the slowing of the rate of translocation.     

Using evolutionary tools to facilitate the prediction and prevention of host‐based differentiation in biological control: a review and perspective

The unprecedented success of biological control (biocontrol) agents led some of the proponents of this technology to promote its use as a panacea for all pest problems. Following an accumulation of non‐target host interactions, because of generalist or new association introductions, techniques to help ensure classical biocontrol agent's success and reduce non‐target interactions were implemented. Even with these new measures in place, public and scientific mistrust and lack of consistency has resulted in increased regulation of biocontrol introductions. This has likely decreased the probability of effective, sustainable control measures being expeditiously implemented. With the current apprehension concerning the safety of biocontrol, we should incorporate the processes (adaptation, selection, etc.) and theoretical concepts of evolutionary biology to predict and enhance the effectiveness of biocontrol. The microevolutionary perspective that involves mutation, drift, selection and gene flow may be a crucial consideration in the realm of biocontrol. Here, we discuss how and why spatial and evolutionary models should be implemented into future risk assessment analyses of potential biocontrol agents. We suggest that it is necessary to re‐assess the approach that has developed over the past approximately 100 years of sustained releases and illuminate them in the context of an evolutionary timescale.     

Heterozygous submicroscopic inversions involving olfactory receptor-gene clusters mediate the recurrent t(4;8)(p16;p23) translocation

The t(4;8)(p16;p23) translocation, in either the balanced form or the unbalanced form, has been reported several times. Taking into consideration the fact that this translocation may be undetected in routine cytogenetics, we find that it may be the most frequent translocation after t(11q;22q), which is the most common reciprocal translocation in humans. Case subjects with der(4) have the Wolf-Hirschhorn syndrome, whereas case subjects with der(8) show a milder spectrum of dysmorphic features. Two pairs of the many olfactory receptor (OR)-gene clusters are located close to each other, on both 4p16 and 8p23. Previously, we demonstrated that an inversion polymorphism of the OR region at 8p23 plays a crucial role in the generation of chromosomal imbalances through unusual meiotic exchanges. These findings prompted us to investigate whether OR-related inversion polymorphisms at 4p16 and 8p23 might also be involved in the origin of the t(4;8)(p16;p23) translocation. In seven case subjects (five of whom both represented de novo cases and were of maternal origin), including individuals with unbalanced and balanced translocations, we demonstrated that the breakpoints fell within the 4p and 8p OR-gene clusters. FISH experiments with appropriate bacterial-artificial-chromosome probes detected heterozygous submicroscopic inversions of both 4p and 8p regions in all the five mothers of the de novo case subjects. Heterozygous inversions on 4p16 and 8p23 were detected in 12.5% and 26% of control subjects, respectively, whereas 2.5% of them were scored as doubly heterozygous. These novel data emphasize the importance of segmental duplications and large-scale genomic polymorphisms in the evolution and pathology of the human genome.     

Synthesis and biological evaluation of a water-soluble derivative of the potent V-ATPase inhibitor archazolid

The water-solubility of the highly potent V-ATPase inhibitors archazolid A and the glucosylated derivative archazolid C was studied in the presence of a wide range of cosolvents, revealing very low solubilites. The first water-soluble analogue was then designed, synthesized, and evaluated for V-ATPase inhibitory activity in vitro.