Sequence signatures of direct complementarity between mRNAs and cognate proteins on multiple levels

A potential connection between physico-chemical properties of mRNAs and cognate proteins, with implications concerning both the origin of the genetic code and mRNA–protein interactions, is unexplored. We compare pyrimidine content of naturally occurring mRNA coding sequences with the propensity of cognate protein sequences to interact with pyrimidines. The latter is captured by polar requirement, a measure of solubility of amino acids in aqueous solutions of pyridines, heterocycles closely related to pyrimidines. We find that the higher the pyrimidine content of an mRNA, the stronger the average propensity of its cognate protein’s amino acids to interact with pyridines. Moreover, window-averaged pyrimidine profiles of individual mRNAs strongly mirror polar-requirement profiles of cognate protein sequences. For example, 4953 human proteins exhibit a correlation between the two with |R| > 0.8. In other words, pyrimidine-rich mRNA regions quantitatively correspond to regions in cognate proteins containing residues soluble in pyrimidine mimetics and vice versa. Finally, by studying randomized genetic code variants we show that the universal genetic code is highly optimized to preserve these correlations. Overall, our findings redefine the stereo-chemical hypothesis concerning code’s origin and provide evidence of direct complementary interactions between mRNAs and cognate proteins before development of ribosomal decoding, but also presently, especially if both are unstructured.     

Reliable micromethod for determination of the protein content in tissue homogenates]

A micromodification for protein determination in tissue material using Amido black 10 B is described. Compared with the method of LOWRY et al. it requires a comparable time expenditure, but has three principal advantages: 1) it is 5-10fold more sensitive; 2) the calibration curve is linear over a virtually unlimited range; 3) it is feasible in the presence of a number of substances frequently used in protein analyses and making difficult or impossible measurement according to LOWRY et al.     

IDH1-Associated Primary Glioblastoma in Young Adults Displays Differential Patterns of Tumour and Vascular Morphology

Glioblastoma is a highly aggressive tumour with marked heterogeneity at the morphological level in both the tumour cells and the associated highly prominent vasculature. As we begin to develop an increased biological insight into the underlying processes driving the disease, fewer attempts have thus far been made to understand these phenotypic differences. We sought to address this by carefully assessing the morphological characteristics of both the tumour cells and the associated vasculature, relating these observations to the IDH1/MGMT status, with a particular focus on the early onset population of young adults who develop primary glioblastoma. 276 primary glioblastoma specimens were classified into their predominant cell morphological type (fibrillary, gemistocytic, giant cell, small cell, oligodendroglial, sarcomatous), and assessed for specific tumour (cellularity, necrosis, palisades) and vascular features (glomeruloid structures, arcades, pericyte proliferation). IDH1 positive glioblastomas were associated with a younger age at diagnosis, better clinical outcome, prominent oligodendroglial and small cell tumour cell morphology, pallisading necrosis and glomeruloid vascular proliferation in the absence of arcade-like structures. These features widen the phenotype of IDH1 mutation-positive primary glioblastoma in young adults and provide correlative evidence for a functional role of mutant IDH1 in the differential nature of neo-angiogenesis in different subtypes of glioblastoma.     

The oxidoreductase PYROXD1 uses NAD(P)+ as an antioxidant to sustain tRNA ligase activity in pre-tRNA splicing and unfolded protein response

1. Download : Download high-res image (107KB)
2. Download : Download full-size image

     

Biomesogenic Matrix Systems

Abstract

The bifunctionally reactive nucleoside and distant nucleoside analogs adenosine (Ado), S-[(adenine-9-yl)methoxyethyl]-L-cysteine (Na-salt) (cysA) and 9-vinyladenine (vA) in aqueous solutions assemble on complementary polyuridylic acid templates to form complex lyomesophases. The systems are investigated by polarizing microscopy, differential scanning calorimetry (DSC) and ¹H- and ³¹P-nmr spectroscopies, assisted by molecular modeling studies. The results indicate the importance of biomesogenic (pre)ordering in nucleic acid native and artificial matrix reactions.     

Directionality of the tympanal vibrations in a cicada: a biophysical analysis

1. Laser vibrometry and acoustic measurements were used to study the biophysics of directional hearing in males and females of a cicada, in which most of the male tympanum is covered by thick, water filled tissue “pads”. 2. In females, the tympanal vibrations are very dependent on the direction of sound incidence in the entire frequency range 1–20 kHz, and especially at the main frequencies of the calling song (3–7 kHz). At frequencies up to 10 kHz, the directionality disappears if the contralateral tympanum, metathoracic spiracle, and folded membrane are blocked with Vaseline. This suggests some pressure-difference receiver properties in the ear. 3. In males, the tympanal vibrations depend on the direction of sound incidence only within narrow frequency bands (around 1.8 kHz and at 6–7 kHz). At frequencies above 10–12 kHz, the directionality appears to be determined by diffraction, and the ear seems to work as a pressure receiver. The peak in directionality at 6–7 kHz disappears when the contralateral timbal, but not the tympanum, is covered. Covering the thin ventral abdominal wall causes the peak around 1.8 kHz to disappear. 4. Most observed tympanal directionalities, except around 1.8 kHz in males, are well predicted from measured transmissions of sound through the body and measured values of sound amplitude and phase at the ears at various directions of sound incidence. Accepted: 18 October 1996