Changes in the composition of ionogenic groups of the wall of the lily pollen grain during germination

Changes in the composition of ionogenic groups of the polymeric matrix of the cell walls of lily (Lilium longiflorum Thunb.) pollen grains were studied during its activation at the early stages of pollen germination. In the cell walls isolated from nonactivated and activated pollen grains, four types of ionogenic groups were identified: amino groups, carboxylic groups of uronic acids, phenolic OH-groups. and groups with pK_a 7–8. During the early stages of germination, ionization constants of each type groups remained unchanged, but the quantitative composition of ionogenic groups in the intine changed. In this matrix, a decrease in the content of phenolic groups and demethylated carboxylic groups of uronic acids was detected. It is supposed that, at early stages of germination, the intine loses some part of acid pectins and some phenolic compounds.     

The role of Cl<Superscript>−</Superscript> in pollen germination and tube growth

The involvement of Cl^? in cytoplasm polarization in the pollen tube and membrane potential control during pollen germination in vitro was studied by fluorescence techniques in Nicotiana tabacum. Cl^? release from cells was blocked by the anion channel inhibitor nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) or by the addition of Cl^? to the incubation medium. The concentrations of the inhibitor (40 μM) and extracellular Cl^? completely inhibiting pollen germination (200 mM) and pollen tube growth (100 mM) were used. The release of anions from the pollen grain has been revealed in the first minutes of hydration also in the presence of 200 mM Cl^?. The inhibitor blocked this process completely, which points to the significance of the NPPB-sensitive anion channels in the transmembrane Cl^? transport at the early activation stage. The pollen tube membrane was hyperpolarized in the presence of 100 mM Cl^?; however, exogenous Cl^? had no effect on the compartmentalization and organelle movement in the tube. The inhibitor depolarized the plasma membrane in the pollen grain and tube and affected the polar organization of the cytoplasm and organelle movement. Thus, activity of NPPB-sensitive chloride channels was required to regulate the potential on the plasma membrane and to maintain the functional compartmentalization of the cytoplasm, which provides for the polar growth.     

KILLER WHALE (ORCINUS ORCA) AUDITORY EVOKED POTENTIALS TO RHYTHMIC CLICKS

Temporal auditory mechanisms were measured in killer whales ( Orcinus orca ) by recording auditory evoked potentials (AEPs) to clicks. Clicks were presented at rates from 10/sec to 1,600/sec. At low rates, clicks evoked an AEP similar to the auditory brainstem response (ABR) of other odontocetes; however, peak latencies of the main waves were 3–3.7 msec longer than in bottlenose dolphins. Fourier analysis of the ABR showed a prominent peak at 300–400 Hz and a smaller one at 800–1,200 Hz. High-rate click presentation (more than 100/sec) evoked a rate-following response (RFR). The RFR amplitude depended little on rate up to 400/sec, decreased at higher rates and became undetectable at 1,120/sec. Fourier analysis showed that RFR fundamental amplitude dependence on frequency closely resembled the ABR spectrum. The fundamental could follow clicks to around 1,000/sec, although higher harmonics of lower rates could arise at frequencies as high as 1,200 Hz. Both RFR fundamental phase dependence on frequency and the response lag after a click train indicated an RFR group delay of around 7.5 msec. This corresponds to the latency of ABR waves PIII-NIV, which indicates the RFR originates as a rhythmic, overlapping ABR sequence. The data suggest the killer whale auditory system can follow high click rates, an ability that may have been selected for as a function of high-frequency hearing and the use of rapid clicks in echolocation.     

血清NGF、BDNF、GFAP水平与老年血管性痴呆严重程度的相关性分析

目的:探讨血清神经生长因子(Nerve Growth Factor,NGF)、脑源性神经营养因子(Brain Derived Neural Nutrition Factor, BDNF)、胶质纤维酸性蛋白(Glial Fibrillary Acidic Protein,GFAP)水平与老年血管性痴呆严重程度的相关性。方法:选择我院2016年1月至2018年12月收治的81例老年血管性痴呆患者,根据简易精神状态检查表(MMES)评分将其分为三组,以MMSE评分21～26分者为轻度组(26例),10～20分者为中度组(28例),0～9分者为重度组(27例),同时选择来院体检的50例健康者作为对照组,检测和比较各组的血清NGF、BDNF、GFAP水平,分析血清NGF、BDNF、GFAP水平与老年血管性痴呆患者MMSE分值的相关性。结果:老年血管性痴呆者的血清NGF、GFAP水平明显高于对照组(P0.05),血清BDNF水平明显低于对照组(P0.05)。轻度组、中度组、重度组的血清NGF、GFAP、BDNF水平对比差异均有统计学意义(P0.05):NGF水平:轻度组中度组重度组,BDNF水平:轻度组中度组重度组;GFAP水平:轻度组中度组重度组。血清NGF、BDNF水平与MMSE分值评分呈显著正相关(r_1=0.652,r_2=0.671,P0.05),血清GFAP水平与MMSE分值呈显著负相关(r3=-0.681,P0.05)。结论:血清NGF、BDNF、GFAP水平均与老年血管性痴呆的严重程度密切相关,可能用于评估老年血管性痴呆病情的严重程度。     

低能离子束促进小麦copia-反转录转座子的转录与转座

LTR-反转录转座子是真核基因组重要的组成部分,能通过RNA中间体完成在基因组上的转座。小麦种子受低能氮离子束注入后能促进其反转录转座子的转录,经不同剂量的氮离子束注入的种子发芽24h和48h后,其中的copia-反转录转座子的转录都有不同程度的提高,最高可达到对照的40倍。用基于反转录转座子扩增多态性和反转录转座子微卫星扩增多态性2种分子标记技术扩增经低能氮离子注入后的小麦DNA,指纹图谱显示出了一定的多态性,这说明低能氮离子束激活了小麦中反转录转座子的转座活性。转座子转录活性的增强可调节其邻近基因的表达和mRNA的拼接,反转录转座子插入到基因组上新的位点后,使基因组上的基因发生了重排,这种重排可能表现为植物表型的改变。因此,推测反转录转座子的转录活性提高和转座激活是产生低能离子束注入生物效应的重要原因之一。     

A Theoretical Graph Method for Search and Analysis of Critical Phenomena in Biochemical Systems. II. Kinetic Models of Biochemical Oscillators Including Two and Three Substances

Four kinetic models of hypothetical complex reactions containing minimal two-substance or three-substance oscillators were constructed on the basis of the graphical rules suggested in the preceding work. The kinetic models are thought to be a part of one of four general biochemical systems: 1) system of mutual protein phosphorylation/dephosphorylation; 2) autophosphorylation of multisubunit protein; 3) association/dissociation of proteins or protein-containing structures during protein–protein or protein–ligand interaction; and 4) two-substrate enzymatic reaction with substrate inhibition by one substrate. Graphical rules of oscillator association with surrounding medium were considered. The graphical criteria of the oscillation generator elimination and criteria of oscillation damping were obtained. Both damped and undamped oscillations of reaction components were obtained by numerical integration of the mathematical models of these reactions. The areas of changes of model parameters and variables, within which the oscillations exist, were found.     

Population structure of Drosophila on quantitative measure traits and its seasonal changes

In the Drosophila population the individuals of medium, small and large size prevail in spring, summer and autumn correspondingly. Such differences are genetically determined. Small individuals are characterized by the highest modification variability while the large individuals--by the lowest one. Genotypic heterogeneity of the population was also found in the body size of individuals, which is the highest in summer and the lowest in autumn. Dynamics of the individual sizes and of genetic heterogeneity is determined by radical seasonal changes in genotypic composition of the population. Such reconstruction influences the substantial part of gene pool, which defines the dimension of individuals. One of the possible reasons of this process is an integral selective action of the population density and temperature. It provides the regulation of variations in numbers and adaptation to the seasonal changes in life conditions.     

A new micromethod for differential quantitative assay of zeatin and zeatin riboside

A new method is proposed for differential quantitative assay of two major endogenous cytokinin forms. It is based on determination of two effective parameters-concentrations of zeatin and zeatin riboside--with the use of appropriate antigens as standards. The method can be used for determining cytokinins in small samples of plant tissues without extract fractionation. This study pioneers in quantitation of changes in the hormonal status of ovules and ovaries of Triticum aestivum L. at early stages of embryogeny. A gradual increase in the content of the active and storage forms of the hormones from the ovary to the ovule was revealed.     

Inorganic ion dynamics in the microspore and pollen grain of tobacco during the development of the male gametophyte

We studied the dynamics of mobile potassium, chloride, and nitrate ions during development of the micro-spore and differentiation of the pollen grain in Nicotiana tabacum L. by measuring their concentration in aqueous extracts from cells destroyed by freezing-thawing using ion-selective electrodes. Stage-specific changes in the ion content and intracellular concentration in the male gametophyte were found. A relationship of the dynamics of ions to growth processes and changes in metabolic activity during gametophytogenesis has been discussed. The changes in the potassium and chloride ion concentrations have been interpreted as regulatory changes controlling protein synthesis in the pollen grain vegetative cell.