Function and evolution of nodulation genes in legumes

Root nodule (RN) symbiosis has a unique feature in which symbiotic bacteria fix atmospheric nitrogen. The symbiosis is established with a limited species of land plants, including legumes. How RN symbiosis evolved is still a mystery, but recent findings on legumes genes that are necessary for RN symbiosis may give us a clue.     

Biology of HLA-G in cancer: a candidate molecule for therapeutic intervention?

Although the expression of the non-classical HLA class I molecule HLA-G was first reported to be restricted to the fetal–maternal interface on the extravillous cytotrophoblasts, the distribution of HLA-G in normal tissues appears broader than originally described. HLA-G expression was found in embryonic tissues, in adult immune privileged organs, and in cells of the hematopoietic lineage. More interestingly, under pathophysiological conditions HLA-G antigens may be expressed on various types of malignant cells suggesting that HLA-G antigen expression is one strategy used by tumor cells to escape immune surveillance. In this article, we will focus on HLA-G expression in cancers of distinct histology and its association with the clinical course of diseases, on the underlying molecular mechanisms of impaired HLA-G expression, on the immune tolerant function of HLA-G in tumors, and on the use of membrane-bound and soluble HLA-G as a diagnostic or prognostic biomarker to identify tumors and to monitor disease stage, as well as on the use of HLA-G as a novel therapeutic target in cancer.     

Fluctuation and response in biology

In 1905, Albert Einstein proposed that the forces that cause the random Brownian motion of a particle also underlie the resistance to macroscopic motion when a force is applied. This insight, of a coupling between fluctuation (stochastic behavior) and responsiveness (non-stochastic behavior), founded an important branch of physics. Here we argue that his insight may also be relevant for understanding evolved biological systems, and we present a ‘fluctuation–response relationship’ for biology. The relationship is consistent with the idea that biological systems are similarly canalized to stochastic, environmental, and genetic perturbations. It is also supported by in silico evolution experiments, and by the observation that ‘noisy’ gene expression is often both more responsive and more ‘evolvable’. More generally, we argue that in biology there is (and always has been) an important role for macroscopic theory that considers the general behavior of systems without concern for their intimate molecular details.     

Molecular enigma of multicolor bioluminescence of firefly luciferase

Firefly luciferase-catalyzed reaction proceeds via the initial formation of an enzyme-bound luciferyl adenylate intermediate. The chemical origin of the color modulation in firefly bioluminescence has not been understood until recently. The presence of the same luciferin molecule, in combination with various mutated forms of luciferase, can emit light at slightly different wavelengths, ranging from red to yellow to green. A historical perspective of development in understanding of color emission mechanism is presented. To explain the variation in the color of the bioluminescence, different factors have been discussed and five hypotheses proposed for firefly bioluminescence color. On the basis of recent results, light-color modulation mechanism of firefly luciferase propose that the light emitter is the excited singlet state of OL⁻ [¹(OL⁻)*], and light emission from ¹(OL⁻)* is modulated by the polarity of the active-site environment at the phenol/phenolate terminal of the benzothiazole fragment in oxyluciferin.     

Visual perception and memory systems: from cortex to medial temporal lobe

Visual perception and memory are the most important components of vision processing in the brain. It was thought that the perceptual aspect of a visual stimulus occurs in visual cortical areas and that this serves as the substrate for the formation of visual memory in a distinct part of the brain called the medial temporal lobe. However, current evidence indicates that there is no functional separation of areas. Entire visual cortical pathways and connecting medial temporal lobe are important for both perception and visual memory. Though some aspects of this view are debated, evidence from both sides will be explored here. In this review, we will discuss the anatomical and functional architecture of the entire system and the implications of these structures in visual perception and memory.     

Beyond natural antimicrobial peptides: multimeric peptides and other peptidomimetic approaches

Naturally occurring antimicrobial peptides (AMPs) present several drawbacks that strongly limit their development into therapeutically valuable antibiotics. These include susceptibility to protease degradation and high costs of manufacture. To overcome these problems, researchers have tried to develop mimics or peptidomimetics endowed with better properties, while retaining the basic features of membrane-active natural AMPs such as cationic charge and amphipathic design. Protein epitope mimetics, multimeric (dendrimeric) peptides, oligoacyllysines, ceragenins, synthetic lipidated peptides, peptoids and other foldamers are some of the routes explored so far. The synthetic approach has led to compounds that have already entered clinical evaluation for the treatment of specific conditions, such as Staphylococcus (MRSA) infections. Should these trials be successful, an important proof-of-concept would be established, showing that synthetic oligomers rather than naturally occurring molecules could bring peptide-based antibiotics to clinical practice and the drug market for local and systemic treatment of medical conditions associated with multi-drug resistant pathogens.