Non-circadian periodicity in the duration of the cell cycle and the G1 phase in the hindlimb epidermis of the anuran tadpole, Rana pipiens

Using the percentage labeled mitoses method, seven cell cycle determinations were initiated at 6-hr intervals over a 36-hr span in order to see if the cell cycle in the tadpole hindlimb epidermis varied with time or showed rhythmicity. There was a pattern of two long cell cycles followed by a shorter one. Total cell cycle length (Tc) and the length of the G1 phase plus one-half of the mitotic time (TG1 + 1/2M) fluctuated the most, although only TG1 + 1/2M varied significantly with the Chi-square test. The proportion of TC spent in each phase was also calculated. Only TG1 + 1/2M/TC had statistically significant fluctuations with time. Rhythmicity was analyzed by a computer program using the method of least squares for cosine curve fitting. Statistically significant ultradian rhythms of 18.4 hr in TC, 18.5 hr in TG1 + 1/2M and 18.6 hr in TG1 + 1/2M/TC and the length of the DNA synthetic phase/total cell cycle length (TS/TC) were found. Circadian rhythmicity was not observed. The acrophases of the ultradian rhythms of TC and TG1 + 1/2M coincided, suggesting that the rhythm of TC was due mainly to variation in TG1 + 1/2M. In the absence of significant variation in TS, the longest phase of the cell cycle, whenever G1 + 1/2M was short, TS/TC increased, so that the 18.6 hr rhythm in TS/TC was also a result of the periodicity in TG1 + 1/2M.     

Sleep and the temperature field of the bed

1. 1. In order to find a correlation between the thermal conditions in bed and the quality of sleep, 5 young, healthy persons were tested in a thermal climate chamber.

2. 2. The sleep of each person was thoroughly monitored during 5 nights (stages I to IV, REM, awake) with continuous registration of 14 temperatures, 12 distributed in the bed, the distal skin temperature and the ambient temperature.

3. 3. Shortly after the test persons went to bed and shortly after they woke up their blood pressure and pulse were taken and they were asked to fill in a questionnaire.

4. 4. The results of this pilot project show a correlation between the quality of sleep and the variations of temperature and that larger fluctuations of temperature in the bed are connected to a shorter deep-sleep time.

5. 5. In order to investigate the thermal comfort it is recommended to undertake detailed analyses of the time and exact interplay between the local thermal conditions during sleep and changes of the sleep-EEG.

Evidence for the occurrence of the alternative, vanadium-containing nitrogenase in the cyanobacterium Anabaena variabilis

Abstract Anabaena variabilis can be grown with dependence on either molybdenum (Mo) or vanadium (V) in the medium with essentially the same growth rates. Vanadium cultures reduce C₂H₂ to C₂H₄ and partly (to 2–3%) to C₂H₆. These C₂H₄ and C₂H₆ formations can be shown to be strictly light dependent, proving that the gases are formed by the cyanobacterium. C₂H₄ and C₂H₆ productions are accompanied by a H₂ formation which is much higher than in Mo cultures. Maximal C₂H₂-formation rates are 2/3 lower in V-grown cells compared to Mo control cultures. This is the first demonstration of a light-dependent ethane formation and of the occurrence of the alternative nitrogenase in any phototroph.     

Controlling the Sporulation of Clostridium sporogenes and the Heat Resistance of the Spores

S ummary . During growth of Clostridium sporogenes in tryptone-salt-peptone-glucose medium the pH value of the medium varies due to formation of acid and CO₂ and to subsequent production of NH₃. Glucose concentrations of 0·2, 0·5 or 1·0% result in increasing sporulation times and in spores of low, extremely high ( D ₁₁₀ c . 80 min) and negligible heat resistance, respectively. When the pH value is maintained at 7, a reproducible sporulation time of a few hours is observed and the resulting spores have a heat resistance ( D ¹¹⁰) of 13 min, regardless of the glucose concentration.     

A variation in the structure of the protein-coding region of the human p53 gene

An extensive analysis of genomic DNA preparations from a number of normal and malignant tissues revealed BglII site polymorphism of the human p53 gene. Approximately 10% of p53 gene alleles were found to contain an additional BglII site localized in a region of intron I. This allelic form of p53 gene was also responsible for p53 protein having altered electrophoretic mobility. Molecular cloning and sequencing of both the alleles of p53 gene revealed a base-pair change in codon 72 causing arginine → proline substitution in the allele with the additional BglII site. Both variants of the p53 gene may occur in homozygous state and are therefore functional.     

A study on the mechanism of the vanadate-dependent NADH oxidation

The mechanism of the vanadate (V(_v))-dependent oxidation of NADH was different in phosphate buffers and in phosphate-free media. In phosphate-free media (aqueous medium or HEPES buffer) the vanadyl (V(_v)) generated by the direct V(_v)-dependent oxidation of NADH formed a complex with V(_v). In phosphate buffers V(_v) autoxidized instead of forming a complex with V(_v). The generated superoxide radical (O₂⁻) initiated, in turn, a high-rate free radical chain oxidation of NADH. Phosphate did not stimulate the V(_v)-dependent NADH oxidation catalyzed by O₂⁻-generating systems. Monovanadate proved to be a stronger catalyzer of NADH oxidation as compared to polyvanadate.     

Radar observations of the stoop of the Peregrine Falcon Falco peregrinus and the Goshawk Accipiter gentilis

Measurements in 10-s intervals by a tracking radar showed average speeds of about 25 ms^-1 for a Peregrine Falcon Falco peregrinus and a Goshawk Accipiter gentilis during four stoops lasting 40–110 s, with angles of dive between 13^o and 64^o, and involving height losses between 450 and 1080 m. Maximum speeds during 10-s intervals were between 31 and 39 ms^-1 in the Peregrine Falcon, and close to 30 ms^-1 in the Goshawk. The observed speeds are well below the maximum possible terminal speeds in steep or vertical dives according to theoretical estimation. By adopting a moderate stooping speed, raptors may gain in hunting precision.     

黑木耳复合群中种类学名说明

黑木耳在我国已经有1 000多年栽培历史,是我国最重要的栽培真菌之一,多年来我国黑木耳的学名一直使用模式产地为欧洲的Auricularia auricula-judae。最近的研究表明A. auricula-judae实际为一复合种,该复合种在全球范围内有5个种。其中A. auricula-judae仅分布于欧洲;美洲有2个种,生长在针叶树上的美洲木耳A. americana和生长在阔叶树上的尚未命名的木耳。中国该类群有3个种：自然分布和栽培最广泛的黑木耳的学名应为A. heimuer,此外,短毛木耳A. villosula在我国东北也广泛分布,并有少量栽培,生长针叶树上的木耳为美洲木耳A. americana,主要分布于中国东北和华北。     

Effects of temperature and current discharge on the concentration and photosynthetic activity of the phytoplankton in the upper Mississippi River

SUMMARY. Temperature and current discharge regulated phytoplanktonic concentration, chlorophyll-a concentration, the light-saturated rate of photosynthesis (P_max), and photosynthetic capacity (P_cap) in the Mississippi River at Prairie Island, Minnesota. The chlorophyll-a maximum was 48 mg m⁻³ in 1975, a wet year with a high current discharge, and 190 mg m⁻³ in 1976, a relatively dry year. The highest values of P_max were 0.37 (mgO₂ I⁻¹h⁻¹) in 1975 and 1.60 in 1976. P_cap varied from 3 to 21 (gO₂ per g chlorophyll-a h⁻¹) both years, and its value was highly correlated with temperature. The temperature optimum shifted from 16°C for P_cap in the spring, to greater than 28°C in the summer. Multiple regression analysis indicated a second-order relationship of P_cap in the spring to temperature. Other independent variables explained only negligible variation of P_cap.     

Involvement of the telomeric protein Pin2/TRF1 in the regulation of the mitotic spindle

Pin2/TRF1 was independently identified as a telomeric DNA-binding protein (TRF1) that regulates telomere length, and as a protein (Pin2) that can bind the mitotic kinase NIMA and suppress its lethal phenotype. We have previously demonstrated that Pin2/TRF1 levels are cell cycle-regulated and its overexpression induces mitotic arrest and then apoptosis. This Pin2/TRF1 activity can be potentiated by microtubule-disrupting agents, but suppressed by phosphorylation of Pin2/TRF1 by ATM; this negative regulation is critical in mediating for many, but not all, ATM-dependent phenotypes. Interestingly, Pin2/TRF1 specifically localizes to mitotic spindles in mitotic cells and affects the microtubule polymerization in vitro. These results suggest a role of Pin2/TRF1 in mitosis. However, nothing is known about whether Pin2/TRF1 affects the spindle function in mitotic progression. Here we characterized a new Pin2/TRF1-interacting protein, EB1, that was originally identified in our yeast two-hybrid screen. Pin2/TRF1 bound EB1 both in vitro and in vivo and they also co-localize at the mitotic spindle in cells. Furthermore, EB1 inhibits the ability of Pin2/TRF1 to promote microtubule polymerization in vitro. Given that EB1 is a microtubule plus end-binding protein, these results further confirm a specific interaction between Pin2/TRF1 and the mitotic spindle. More importantly, we have shown that inhibition of Pin2/TRF1 in ataxia-telangiectasia cells is able to fully restore their mitotic spindle defect in response to microtubule disruption, demonstrating for the first time a functional involvement of Pin2/TRF1 in mitotic spindle regulation.     

The Pmr1 protein, the major yeast Ca2+-ATPase in the Golgi, regulates intracellular levels of the cadmium ion

Cadmium is a nonessential, highly toxic heavy metal that shows ionic properties similar to calcium. These ionic similarities imply that the cadmium ion, Cd²⁺, is a calcium ion, Ca²⁺, receptor-agonist, affecting the same biochemical pathways involved in Ca²⁺ homeostasis. In the yeast Saccharomyces cerevisiae , the PMC1 and PMR1 genes encode vacuolar and Golgi Ca²⁺-ATPases, respectively. The PMR1 protein product Pmr1p is involved in both Ca²⁺ and Mn²⁺ homeostasis. This study investigated the importance of Pmc1p and Pmr1p for Cd²⁺ cellular detoxification. Using the standard techniques of yeast molecular research and a multielemental procedure named particle-induced X-ray emission, Pmr1p was identified as a protein that directly participates in the detoxification of Cd²⁺, possibly through the secretory pathway. The results allow us to posit a model of Cd²⁺ detoxification where Pmr1p has a central role in cell survival in a Cd²⁺-rich environment.     

Technical Procedures for the Study of the Nucleolonema

In a recent paper¹ the authors have shown filamentous structures within the nucleolus of all cells. This structure was named the nucleolonema. In the present paper the technical procedures which prove their existence are described in detail.

There are two groups: a) Silver impregnation procedures and iron-pyrogallic stain for fixed material; b) phase contrast microscopy, dark-field illumination and oblique transillumination for fresh material.

The suitable objects are mentioned in every case in order to obtain the best results.     

Requirements for the phosphorylation of the Escherichia coli EIIANtr protein in vivo

The nitrogen-related phosphotransferase system (Ntr-PTS) is a paralogous system working in parallel to the well-known carbohydrate:PTS. In a chain of phosphotransfer reactions, EI^Ntr and NPr (PtsO) deliver phosphoryl groups to the EIIA^Ntr (PtsN) protein. EIIA^Ntr is implicated in important regulatory processes such as the σ^E-dependent cell envelope stress response and regulation of K⁺ uptake. Phosphorylation is believed to trigger the output of EIIA^Ntr in these regulations. EIIA^Ntr is encoded within the gene cluster ptsN–yhbJ–ptsO , which is highly conserved in Proteobacteria . In this study, we investigated the phosphorylation of the Escherichia coli EIIA^Ntr protein in vivo by ³²P-labeling. We show that EIIA^Ntr is readily phosphorylated in wild-type cells. This phosphorylation occurs at a single site, the histidine 73 in EIIA^Ntr. YhbJ and NPr are dispensable for this phosphorylation. A detailed analysis revealed that both the energy coupling phosphotransferases of the Ntr-PTS as well as the 'sugar'-PTS contribute to the phosphorylation of EIIA^Ntr, suggesting cross talk between both systems.     

Reinforcing the idea of signalling in the stomatal pathway

Stomata are plant epidermal structures that regulate gas exchange with the atmosphere. In Arabidopsis, mutations in TOO MANY MOUTHS (TMM) disrupt a range of processes related to stomatal development and patterning. Recently, the sequence and the expression pattern of TMM were reported. TMM encodes a leucine-rich-repeat-containing, receptor-like protein that lacks a cytoplasmic kinase domain and that is expressed in postprotodermal cells. Several lines of evidence suggest that TMM and STOMATAL DENSITY AND DISTRIBUTION1, a putative subtilisin-like serine protease, might act in the same signalling pathway.     

101 Exploring the 3D spatial organization of the genome

Knowledge about the 3D organization of the genome will offer great insights into how cells retrieve and process the genetic information. Knowing the spatial probability distributions of individual genes will provide insights into gene regulatory and replication processes, and fill in the missing links between epigenomics, functional genomics, and structural biology. We will discuss an approach to determine 3D genome structures and structure–function maps of genomes by integrating divers types of data. To address the challenge of modeling highly variable genome structures, we discuss a population-based modeling approach, where we construct a large population of 3D genome structures that together are entirely consistent with all available experimental data including data from genome-wide chromosome conformation capture and imaging experiments. We interpret the result in terms of probabilities of a sample drawn from a population of heterogeneous structures. We will discuss results on the 3D spatial organization of genomes in human lymphoblastoid cells and budding yeast.     

Amino Acids Responsible for the Absolute Sialidase Activity of the Influenza A Virus Neuraminidase: Relationship to Growth in the Duck Intestine

The 1957 human pandemic strain of influenza A virus contained an avian virus hemagglutinin (HA) and neuraminidase (NA), both of which acquired specificity for the human receptor, N-acetylneuraminic acid linked to galactose of cellular glycoconjugates via an alpha2-6 bond (NeuAcalpha2-6Gal). Although the NA retained considerable specificity for NeuAcalpha2-3Gal, its original substrate in ducks, it lost the ability to support viral growth in the duck intestine, suggesting a growth-restrictive change other than a shift in substrate specificity. To test this possibility, we generated a panel of reassortant viruses that expressed the NA genes of human H2N2 viruses isolated from 1957 to 1968 with all other genes from the avian virus A/duck/Hong Kong/278/78 (H9N2). Only the NA of A/Singapore/1/57 supported efficient viral growth in the intestines of orally inoculated ducks. The growth-supporting capacity of the NA correlated with a high level of enzymatic activity, comparable to that found to be associated with avian virus NAs. The specific activities of the A/Ann Arbor/6/60 and A/England/12/62 NAs, which showed greatly restricted abilities to support viral growth in ducks, were only 8 and 5%, respectively, of the NA specific activity for A/Singapore/1/57. Using chimeric constructs based on A/Singapore/1/57 and A/England/12/62 NAs, we localized the determinants of high specific NA activity to a region containing six amino acid substitutions in A/England/12/62: Ser331-->Arg, Asp339-->Asn, Asn367-->Ser, Ser370-->Leu, Asn400-->Ser, and Pro431-->Glu. Five of these six residues (excluding Asn400) were required and sufficient for the full specific activity of the A/Singapore/1/57 NA. Thus, in addition to a change in substrate specificity, a reduction in high specific activity may be required for the adaptation of avian virus NAs to growth in humans. This change is likely needed to maintain an optimal balance between NA activity and the lower affinity shown by human virus HAs for their cellular receptor.