Presence of RNA in the sperm nucleus

The RNase-colloidal gold procedure for the ultrastructural localization of RNA was used for rat testis. Along with other structures, it was found that the testicular sperm nucleus was well stained. Similar labelling was observed in the nucleus of rat epididymal sperm and human sperm. The RNA was extracted from sperm and analyzed by electrophoresis on 10% polyacrylamide gel and 7 M urea. The electrophoretic profile revealed a complex set of bands ranging in size from tRNA to high molecular weight components. On the average, a content of about 0.1 pg of RNA per rat or human sperm was found.     

Cell Proliferation in the Presence of Telomerase

Background

Telomerase, which is active early in development and later in stem and germline cells, is also active in the majority of human cancers. One of the known functions of telomerase is to extend the ends of linear chromosomes, countering their gradual shortening at each cell division due to the end replication problem and postreplication processing. Telomerase concentration levels vary between different cell types as well as between different tumors. In addition variable telomerase concentrations will exist in different cells in the same tumor when telomerase inhibitors are used, because of limitations of drug delivery in tissue. Telomerase extends short telomeres more frequently than long telomeres and the relation between the extension frequency and the telomere length is nonlinear.

Methodolgy/Principal Findings

Here, the biological data of the nonlinear telomerase-telomere dynamics is incorporated in a mathematical theory to relate the proliferative potential of a cell to the telomerase concentration in that cell. The main result of the paper is that the proliferative capacity of a cell grows exponentially with the telomerase concentration.

Conclusions/Significance

The theory presented here suggests that long term telomerase inhibition in every cancer progenitor or cancer stem cell is needed for successful telomere targeted cancer treatment. This theory also can be used to plan and asses the results of clinical trials targeting telomerase.     

Antibiotic Activity in the Presence of Agar

Agar has been shown to interfere with the activity of some antibiotics against Staphylococcus aureus. This interference has been observed as an increase in the minimal inhibitory concentration and in the diameter of the zone of inhibition. Purifying the agar with water extractions substantially reduced this adverse effect.     

Presence of abnormal cells

Automated WBC differential counters will identify only a limited number of cells but may do this very precisely and accurately. In a cancer center and in an orthopedic center, 10% and 6%, respectively, of all admissions will have circulating "abnormal" cells that might be missed by the automated instruments. Abnormal cells include blasts, promyelocytes, myelocytes, metamyelocytes, bands, reactive and immature lymphocytes and nucleated red cells. Eosinophilia and basophilia also have clinical implications. The argument is made that a screening method that fails to detect such cells may be inadequate and a simple practical solution is proposed. This will not eliminate the need for a stained smear but will reduce the call for a labor intensive manual differential count.     

Precipitation of Protein in the Presence of Melanoidin

A melanoidin was prepared by the reaction of glycine-d-glucose system. The fraction of melanoidin between 10,000 and 50,000 in molecular weight was mainly used to clarify its interaction with protein. Remarkable precipitation was observed between the isoelectric points of melanoidin (pH 2.5) and ovalbumin (pH 4.6). An increase of ionic strength restricted those interaction. As the concentration of melanoidin rose against protein in the reaction system, the molar ratio (protein/melanoidin) in precipitate fell towards 1:1. When the melanoidin was in excess beyond a certain level, precipitation hardly happened. The composition in the reaction system to attain the maximum rate of precipitation was affected by molecular weight of melanoidin. Precipitation proceeded according to second order reaction in respect to both ovalbumin and melanoidin. Based on the analysis of Arrhenius plots, precipitation was found to be promoted by the two subsequent steps. A mechanism involved in this reaction was proposed.     

Presence of rhodopsin-like proteins in the planarian head

The presence of rhodopsin-like protein was detected in the head of the freshwater planarian Dugesia japonica japonica Ichikawa et Kawakatsu by use of anti-frog-rhodopsin rabbit IgG. Two membrane proteins of molecular weights 65000 and 62000 were separated by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis and found to react with the anti-rhodopsin IgG. The antibody may be useful for monitoring regeneration of the planarian eye.     

基干啮型类发现跟骨管结构（英文）

2002年Bleefeld和Bock发现跟骨上一个独特的解剖结构——跟骨管——仅在现生与化石兔形目种类中存在,而在啮齿类以及相关类群中缺如,并认为这个独特的解剖特征支持了兔形目是一个单系类群。对安徽潜山古新世地层中发现的基干啮型类标本(IVPP V 7422)的观察表明其跟骨上也存在清晰的跟骨管,使得我们重新审视这一独特解剖特征。结合显微镜观察与CT扫描技术,发现兔形目种类,如Dawsonolagus,Ordolagus等存在较大的跟骨管,其进口与出口皆与骨体内部髓腔贯通;在双门齿啮型类如Mimolagus,Gomphos,单门齿啮型类Rhombomylus上也存在清晰的跟骨管。因此,跟骨管的存在可能是啮型类的共近裔性状,也支持了兔形类与啮齿类具有更近的亲缘关系。     

Reactor Performance in the Presence of Catalyst Deactivation

The main variable of enzymatic processes is often found to be the operating temperature. An increase in temperature leads to higher rates for the catalytic transformation. However, beyond a certain temperature catalyst deactivation is winning the game. Therefore, processes should be optimized in order to determine the temperature which leads to a minimal demand of enzyme preparation. For the prediction of such optimal reactor operation, modeling of the temperature dependence of the process has to be performed. Examples of such modeling are given for the hydrolysis of lactose in UHT milk by means of three different β‐galactosidases – those from Aspergillus oryzae, Kluyveromyces lactis, and Escherichia coli. The reaction kinetics for a constant initial lactose concentration can be described by a model of two parameters, of which only one depends on temperature. For the lactase of E. coli the reaction can be described as a simple reaction with first order kinetics. The deactivation mechanism includes a reversible as well as an irreversible path of denaturation. The temperature dependent parameters follow Arrhenius' and van't Hoff's law, respectively. On the basis of their particular reaction models all three enzymes can be compared with respect to their optimum use. The models have been verified under laboratory conditions and have shown their usefulness for the prediction of optimum operating variables. Quite remarkable features have been found for the lactase of E. coli.     

Presence of Kynurenic Acid in the Mammalian Brain

Kynurenic acid, a tryptophan metabolite able to antagonize the actions of the excitatory amino acids, has been identified and measured for the first time in the brain of mice, rats, guinea pigs, and humans by using an HPLC method. Its content was 5.8 +/- 0.9 in mouse brain, 17.8 +/- 2.0 in rat brain, 16.2 +/- 1.5 in guinea pig brain, 26.8 +/- 2.9 in rabbit brain, and 150 +/- 30 in human cortex (pmol/g wet wt. mean +/- SE). The regional distribution of this molecule was uneven. In rats, guinea pigs, and rabbits, the brainstem was the area richest in this compound. Tryptophan administration (100-300 mg/kg, i.p.) to rats resulted in a significant increase of the brain content of kynurenic acid. Similarly, 1 h after probenecid administration (200 mg/kg, i.p.), the brain content of kynurenate increased by fourfold, thus suggesting that its turnover rate is relatively fast.     

Estimating Relatedness in the Presence of Null Alleles

Studies of genetics and ecology often require estimates of relatedness coefficients based on genetic marker data. However, with the presence of null alleles, an observed genotype can represent one of several possible true genotypes. This results in biased estimates of relatedness. As the numbers of marker loci are often limited, loci with null alleles cannot be abandoned without substantial loss of statistical power. Here, we show how loci with null alleles can be incorporated into six estimators of relatedness (two novel). We evaluate the performance of various estimators before and after correction for null alleles. If the frequency of a null allele is <0.1, some estimators can be used directly without adjustment; if it is >0.5, the potency of estimation is too low and such a locus should be excluded. We make available a software package entitled PolyRelatedness v1.6, which enables researchers to optimize these estimators to best fit a particular data set.     

Presence of melatonin in the human hepatobiliary-gastrointestinal tract

A variety of speculations about the possible origin and physiological role of the neurohormone melatonin in the gastrointestinal tract exist. However, the experimental evidence supporting any of these theories is not substantial and are missing for humans. We studied the distribution of melatonin which was measured with radioimmunoassay in the following compartments and organs of the human hepatobiliary-gastrointestinal tract: bile (obtained by endoscopic retrograde cholangiopancreaticography), peripheral venous and portal venous blood (obtained from patients undergoing liver transplantation), endoscopically derived biopsies (mainly consisting of mucosa and submucosa) of stomach, duodenum, large intestine as well as in resected liver tissue. Melatonin concentrations in gastrointestinal mucosa were between 136 +/- 27 pg/100 mg (stomach) and 243 +/- 37 pg/100 mg (descending colon, each n = 5). Biliary melatonin concentrations (85 +/- 45 pg/ml) correlated well with plasma concentrations (55 +/- 38 pg/ml, each n = 14) and a considerable amount of melatonin (about 51 ng/24 hours) appears to be excreted into the gut via the bile duct. Melatonin concentrations were slightly higher in portal than in peripheral venous blood and also the liver contained higher concentrations of melatonin than the blood. In conclusion the presence and distribution of melatonin in human gut, bile, liver and portal blood and the various reports on modulatory actions of melatonin on gut and liver functions suggest that melatonin may act as a mediator of inter-organ communication between gut and liver.