Small-scale patterns of forest plants and environmental heterogeneity

Small-scale pattern analysis of plant populations was done in nine forest communities of the Moscow region (USSR). In most cases the vegetatively immobile and low-mobile species were found to have less contagious distributions than vegetatively mobile species. In different communities one and the same species may display a different kind of pattern, though no relationship between the abundance of species and the kind of its spatial distribution could be identified. Ecological indicator values were used to obtain data on the variability of environmental parameters inside the communities. Environmental heterogeneity appears to be the major factor determining the kind of vascular plant pattern. The kind of distribution of bryophytes (as a rule, high-contagious) is insignificantly related to environmental heterogeneity.     

Characteristics of kinetoplastic DNA from Leptomonas pessoai

The kinetoplast (mitochondrial) DNA from trypanosomatid Leptomonas pessoai represents a network, composed of mini-circles heterogeneous in base sequence and homogeneous maxi-circles and thus has the main structural features in common with DNAs from kinetoplasts of other Trypanosomatidae. The size of mini-circular molecules of DNA is 1,35 kilobase pairs (kbp) and that of maxicircular molecules-30,9 kbp. Based on the data of single and double restriction cleavages the physical map of the maxi-circular molecules was constructed for the endonucleases BamHI, BglII, BspI , HindIII, MspI, SalGI and PstI.     

Titration of active centers of enzymes by means of reversible inhibitors. Dipeptidyl-carboxypeptidase - inhibitor SQ 20881 from venom of the snake Bothrops jararca)

The essentials of estimation of the number of enzyme active sites by reversible inhibition are discussed. The necessity of evaluation of the substrate effect on the equilibrium of the systems with a rapidly dissociating enzyme -- inhibitor complex has been demonstrated. Some procedures for determination of the number of active sites of dipeptidyl-carboxypeptidase (EC 3.4.15.1) from bovine kidney cortex, using the competitive inhibitor SQ 20 881 (Glu-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro) have been developed. The kinetic and equilibrium constants for the enzyme-inhibitor interaction (ki = 3.2 . 10(6) M-1s-1, k-i = 8 ms-1 and Ki = 2.5 +/- 0.5 nm) have been calculated.     

Role of κ1 opioid receptors and cAMP in regulation of cardiac tolerance to ischemia and reperfusion

Cardioprotective, inotropic, and antiarrhythmic effects of the selective agonist of κ₁ opioid receptors (κ₁-ORs) U-50.488H have been studied after 45-min global ischemia and 30-min reperfusion of isolated perfused rat hearts. The heart κ₁-ORs were stimulated by adding 0.1 or 1 μmol/l U-50.488H to the perfusion solution. The opioid did not affect the frequency of reperfusion arrhythmias. At a concentration of 0.1 μmol/l, it induced a twofold decrease in the reperfusion release of creatine phosphokinase (CPK), which positively correlated with a decrease in the myocardial cAMP level (r = 0.89, p < 0.01). Application of U-50.488H at a final concentration of 1 μmol/l did not change the cAMP level and CPK release. These results suggest that the cardioprotective effect of U-50.488H is due to a decrease in the level of cAMP in cardiomyocytes. Activation of κ₁-ORs decreased the frequency and force of myocardial contractions. It has been shown that the negative inotropic and chronotropic effects of U-50.488H are independent of changes in the myocardial cAMP level. A hypothesis is proposed that the absence of cardioprotective effect of 1μM U-50.488H is a result of activation of nonopioid receptors in cardiomyocytes.     

Uncharged Gemini-Amphiphiles as Components of Cationic Liposomes for Delivery of Nucleic Acids

Russian Journal of Bioorganic Chemistry - New uncharged gemini-amphiphiles have been synthesized. A series of cationic liposomes based on the polycationic amphiphile...     

Three-dimensional Optical-resolution Photoacoustic Microscopy

Optical microscopy, providing valuable insights at the cellular and organelle levels, has been widely recognized as an enabling biomedical technology. As the mainstays of in vivo three-dimensional (3-D) optical microscopy, single-/multi-photon fluorescence microscopy and optical coherence tomography (OCT) have demonstrated their extraordinary sensitivities to fluorescence and optical scattering contrasts, respectively. However, the optical absorption contrast of biological tissues, which encodes essential physiological/pathological information, has not yet been assessable. The emergence of biomedical photoacoustics has led to a new branch of optical microscopy optical-resolution photoacoustic microscopy (OR-PAM)¹, where the optical irradiation is focused to the diffraction limit to achieve cellular¹ or even subcellular² level lateral resolution. As a valuable complement to existing optical microscopy technologies, OR-PAM brings in at least two novelties. First and most importantly, OR-PAM detects optical absorption contrasts with extraordinary sensitivity (i.e., 100%). Combining OR-PAM with fluorescence microscopy³ or with optical-scattering-based OCT⁴ (or with both) provides comprehensive optical properties of biological tissues. Second, OR-PAM encodes optical absorption into acoustic waves, in contrast to the pure optical processes in fluorescence microscopy and OCT, and provides background-free detection. The acoustic detection in OR-PAM mitigates the impacts of optical scattering on signal degradation and naturally eliminates possible interferences (i.e., crosstalks) between excitation and detection, which is a common problem in fluorescence microscopy due to the overlap between the excitation and fluorescence spectra. Unique for optical absorption imaging, OR-PAM has demonstrated broad biomedical applications since its invention, including, but not limited to, neurology^{5, 6}, ophthalmology^{7, 8}, vascular biology⁹, and dermatology¹⁰. In this video, we teach the system configuration and alignment of OR-PAM as well as the experimental procedures for in vivo functional microvascular imaging.Download video file.^{(52M, mov)}