Measurement of Primary Productivity in Dense Algal Cultures

1983 ◽  
Vol 40 (6) ◽  
pp. 807-810 ◽  
Author(s):  
S-R. Gentner
Keyword(s):  
Primary Productivity ◽  
Growth Cycle ◽  
Exponential Phase ◽  
Scintillation Counting ◽  
Late Exponential Phase ◽  
Limited Sample ◽  
Productivity Measurement ◽  
Limited Sample Size ◽  
Scenedesmus Acutus ◽  
Algal Cultures

The 14C-bicarbonate method of primary productivity measurement was modified for dense algal cultures by the addition of NaHCO3 to avoid exhaustion of carbon source. Using this method plus a modified procedure for scintillation counting of limited sample size, six species of chlorophyean algae were studied daily throughout the growth cycle. Scenedesmus acutus was the most productive with a peak productivity of 5.3 mg C∙L−1∙h−1 at 9.7 × 103 lx during late exponential phase. Peak productivity values (mg C∙L−1∙h−1) for the other species were 2 for Chlorella vulgaris, 2.3 for Ankistrodesmus braunii, and 3.4, 3.5, and 3.6 mg C∙L−1∙h−1 for Scenedesmus basiliensis, S. bijugatus, and S. parisiensis, respectively.

scholarly journals The mannophosphoinositides of Corynebacterium aquaticum

1975 ◽  
Vol 148 (2) ◽  
pp. 253-258 ◽  
Author(s):  
J A Hackett ◽  
P J Brennan
Keyword(s):  
Stationary Phase ◽  
Exponential Growth ◽  
Growth Cycle ◽  
Exponential Phase ◽  
Late Stationary Phase ◽  
Late Exponential Phase

Besides the monomannophosphoinositide previously reported in Corynebacterium aquaticum small amounts of other, apparently more glycosylated, mannophosphoinositides have been identified in stationary phase cells. Moreover, by labelling cells with [32P]Pi, phosphatidylinositol was found, comprising about 1.5% of the stationary-phase phospholipids. 2. Pulse-chase experiments performed on cells in the late exponential phase of growth further suggested the sequence phosphatidylinositol leads to monomannophosphoinositide as the first step in the biosynthesis of the mannophosphoinositides. 3. Di-and tri-mannophosphoinositides are apparently the main mannophosphoinositides present during exponential growth. Monomannophosphoinositide predominates only in late stationary phase; in the earlier stationary phase, phosphatidylinositol comprises 50% of the phosphoinositide lipid, and tetramannophosphoinositide constitutes much of the remainder. 4. The metabolism and functions of the mannophosphoinositides are discussed, particularly in relation to changes in their composition throughout the growth cycle.

Identification d'une nucléotide pyrophosphatase exocellulaire dans le milieu de culture de Streptomyces mediterranei ME/R 17

1979 ◽  
Vol 25 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Gérard Pellon ◽  
Georges Michel
Keyword(s):  
Enzyme Preparation ◽  
Culture Medium ◽  
Deae Cellulose ◽  
Growth Cycle ◽  
Exponential Phase ◽  
Nucleotidase Activity ◽  
Late Exponential Phase ◽  
Nucleotide Pyrophosphatase ◽  
Pyrophosphatase Activity ◽  
Positive Effect

An exocellular pyrophosphatase, active on the nucleotide precursors of peptidoglycans, has been found in the culture medium of Streptomyces mediterranei ME/R 17. This enzyme was separated from the DD-carboxypeptidase by batchwise adsorption on DEAE cellulose. The pyrophosphatase had no strict substrate requirements, it hydrolyzed various UDP-sugar substrates: UDP-GlcNAc. UDP-MurNAc and UDP-MurNAc peptides, giving rise to the corresponding sugar phosphate and to UMP. The enzyme preparation also contained a 5′-nucleotidase activity and UMP was further split to give uridine. This nucleotidase activity was inhibited by potassium tetraborate. Both cytoplasmic and particulate preparations from cells of S. mediterranei also contained a pyrophosphatase activity while only the particulate fractions showed the DD-carboxypeptidase activity.The pyrophosphatase excretion was tested during the growth cycle. The activity of the enzyme showed a constant increase throughout the exponential growth and a stronger increase in the late exponential phase. Such a result could be correlated with a consumption of the nutrients in the culture medium, in fact a relatively poor culture medium had a strong positive effect upon the production of the exocellular pyrophosphatase.

scHinter: imputing dropout events for single-cell RNA-seq data with limited sample size

2019 ◽  
Author(s):  
Pengchao Ye ◽  
Wenbin Ye ◽  
Congting Ye ◽  
Shuchao Li ◽  
Lishan Ye ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sample Size ◽  
Single Cell ◽  
Wide Spectrum ◽  
Dropout Rate ◽  
Supplementary Information ◽  
Sample Sizes ◽  
Limited Sample ◽  
Limited Sample Size ◽  
The Impact

Abstract Motivation Single-cell RNA-sequencing (scRNA-seq) is fast and becoming a powerful technique for studying dynamic gene regulation at unprecedented resolution. However, scRNA-seq data suffer from problems of extremely high dropout rate and cell-to-cell variability, demanding new methods to recover gene expression loss. Despite the availability of various dropout imputation approaches for scRNA-seq, most studies focus on data with a medium or large number of cells, while few studies have explicitly investigated the differential performance across different sample sizes or the applicability of the approach on small or imbalanced data. It is imperative to develop new imputation approaches with higher generalizability for data with various sample sizes. Results We proposed a method called scHinter for imputing dropout events for scRNA-seq with special emphasis on data with limited sample size. scHinter incorporates a voting-based ensemble distance and leverages the synthetic minority oversampling technique for random interpolation. A hierarchical framework is also embedded in scHinter to increase the reliability of the imputation for small samples. We demonstrated the ability of scHinter to recover gene expression measurements across a wide spectrum of scRNA-seq datasets with varied sample sizes. We comprehensively examined the impact of sample size and cluster number on imputation. Comprehensive evaluation of scHinter across diverse scRNA-seq datasets with imbalanced or limited sample size showed that scHinter achieved higher and more robust performance than competing approaches, including MAGIC, scImpute, SAVER and netSmooth. Availability and implementation Freely available for download at https://github.com/BMILAB/scHinter. Supplementary information Supplementary data are available at Bioinformatics online.

Redescription of Clubiona blesti Forster, 1979 (Araneae: Clubionidae) with a preliminary molecular phylogeny of New Zealand Clubiona

Zootaxa ◽  
2012 ◽  
Vol 3277 (1) ◽  
pp. 27 ◽  
Author(s):  
JAGOBA MALUMBRES-OLARTE ◽  
COR J. VINK
Keyword(s):  
Phylogenetic Analysis ◽  
New Zealand ◽  
Wide Distribution ◽  
Dispersal Ability ◽  
Mtdna Sequences ◽  
Limited Sample ◽  
Limited Sample Size ◽  
Geographic Structure ◽  
Molecular Phylogenetic ◽  
First Time

The New Zealand spider Clubiona blesti Forster, 1979 is redescribed, with the male described for the first time, and a pre-liminary molecular phylogenetic analysis of cytochrome c oxidase subunit I (COI) mtDNA sequences for eight species ofNew Zealand Clubiona and an outgroup from Tasmania is presented.There is considerable intraspecific variation in C. blesti, both genetic and in the morphology of copulatory organs,which may be explained by its wide distribution. The lack of a geographic structure based on consistent differences be-tween populations may suggest great dispersal ability. Given the limited sample size, further sampling and data on addi-tional genetic markers will be necessary to confirm this.The phylogenetic analysis of seven more species indicated that Clubiona cambridgei is the sister species of C. blestiand confirmed the existence of at least two monophyletic groups among the New Zealand Clubiona: species with a striped abdomen and with a spotted abdomen.

Response of Liverwort Cells to Peroxidizing Herbicides

1992 ◽  
Vol 47 (5-6) ◽  
pp. 394-399
Author(s):  
Shuji Iwata ◽  
Naoko Nakayama ◽  
Shunji Nakagawara ◽  
Yoshimoto Ohta ◽  
Takaharu Tanaka ◽  
...  
Keyword(s):  
Cell Growth ◽  
Oxidative Damage ◽  
Early Treatment ◽  
Protoporphyrin Ix ◽  
Cell Suspension Cultures ◽  
Exponential Phase ◽  
Marchantia Polymorpha ◽  
Late Exponential Phase ◽  
Kinetics Of

Cell suspension cultures of the liverwort, Marchantia polymorpha L. were found useful to study the influence of peroxidizing herbicides either on the greening process or on the fully green cells. The cells of both physiological stages exhibit a characteristic sensitivity to the herbicides. The sensitivity increased rapidly during the exponential phase of growth, reached a maximum during the late exponential phase, and then decreased in the stationary phase. We investigated the kinetics of accumulation of protoporphyrin IX (PPIX) in Marchantia cells treated with several peroxidizing herbicides at various stages of cell growth, and observed a correlation between accumulation of PPIX and herbicidal damage. The glutathione (GSH) content in the cell was also investigated to examine the role of GSH against herbicide treatment. In the light, GSH levels in the cells treated with AFM rose rapidly reaching a peak after 8 h, and rapidly decreased subsequently. The beginning of PPIX accumulation coincided with the decline of GSH after 8 h of treatment. Obviously, GSH plays a key role in protection against oxidative damage caused by AFM in the early treatment period. In the dark, AFM also induced an accumulation of GSH and PPIX, followed by a decline in GSH and PPIX contents during a 20 h incubation. The decline of PPIX was observed several hours after GSH starts to decrease, remaining at a constant level for the following 40 h, leading to accumulation of an other fluorescent still-unknown pigment.

The predictive performances of random forest models with limited sample size and different species traits

2020 ◽  
Vol 227 ◽  
pp. 105534 ◽  
Author(s):  
Jing Luan ◽  
Chongliang Zhang ◽  
Binduo Xu ◽  
Ying Xue ◽  
Yiping Ren
Keyword(s):  
Random Forest ◽  
Sample Size ◽  
Species Traits ◽  
Limited Sample ◽  
Limited Sample Size ◽  
Forest Models ◽  
Random Forest Models

scholarly journals Visual Hallucinations as Incidental Negative Effects of Virtual Reality on Parkinson’s Disease Patients: A Link with Neurodegeneration?

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Giovanni Albani ◽  
Elisa Pedroli ◽  
Pietro Cipresso ◽  
Daniel Bulla ◽  
Veronica Cimolin ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Virtual Reality ◽  
Clinical History ◽  
Immersive Virtual Reality ◽  
Visual Hallucinations ◽  
Negative Effects ◽  
Limited Sample ◽  
Limited Sample Size ◽  
Immersive Systems

We followed up a series of 23 Parkinson’s disease (PD) patients who had performed an immersive virtual reality (VR) protocol eight years before. On that occasion, six patients incidentally described visual hallucinations (VH) with occurrences of images not included in the virtual environment. Curiously, in the following years, only these patients reported the appearance of VH later in their clinical history, while the rest of the group did not. Even considering the limited sample size, we may argue that VR immersive systems can induce unpleasant effects in PD patients who are predisposed to a cognitive impairment.

Respect Redefined: Focus Group Insights from Singapore

1997 ◽  
Vol 44 (3) ◽  
pp. 205-219 ◽  
Author(s):  
Kalyani Mehta
Keyword(s):  
Focus Group ◽  
Social Workers ◽  
Interpersonal Relationships ◽  
Multicultural Society ◽  
Limited Sample ◽  
Social Scientists ◽  
Limited Sample Size ◽  
The Family ◽  
Focus Group Methodology ◽  
Subjective Views

This article re-examines the meaning of the concept of respect within the context of a fast modernizing Asian multicultural society—Singapore. Two key findings emerge. First, the meaning of respect both from the perspective of the aged and the middle-aged generation has shifted from obedience to courteous behavior. Second, in the majority of focus groups members concurred that the degree of respect accorded to elders has in general decreased. The focus group methodology was used in this research. Bearing in mind the limited sample size (88 participants) these findings alert us to the need for social scientists to monitor perceptual shifts in meaning of concepts critical in the sphere of interpersonal relationships. The findings throw light on the subjective views of intergenerational relations within the family as well as the community. As such, they would be valuable to counselors, social workers, and family therapists.

scholarly journals The effect of inhibitors on the oxygen kinetics of terminal oxidases of Acanthamoeba castellanii

1979 ◽  
Vol 182 (1) ◽  
pp. 11-15 ◽  
Author(s):  
D Lloyd ◽  
S Edwards ◽  
B Kristensen ◽  
H Degn
Keyword(s):  
Competitive Inhibition ◽  
Acanthamoeba Castellanii ◽  
Exponential Phase ◽  
Oxygen Utilization ◽  
Late Exponential Phase ◽  
Salicylhydroxamic Acid ◽  
Terminal Oxidases ◽  
Low Concentrations ◽  
Transport Chain ◽  
Oxygen Sensitive

1. Respiration of growing cultures of Acanthamoeba castellanii is inhibited less than 60% by azide (35 mM); the respiration of early-exponential-phase cultures differs from that of late-exponential-phase cultures in being stimulated by up to 120% by low concentrations (less than 1 mM) of this inhibitor. Azide (0.5 mM) plus 1 mM-salicylhydroxamic acid gives 80% inhibition of respiration in early- or late-exponential-phase cultures. 2. Lineweaver-Burk plots of 1/v against 1/[O2] for growing and stationary-phase cultures give values of less than 1 muM for the apparent Km for oxygen. 3. These values are not significantly altered when determined in the presence of 1 mM-salicylhydroxamic acid. 4. Higher values (greater than 7 muM) for apparent Km values for oxygen were obtained in the presence of azide, which gives non-linear Lineweaver-Burk plots. 5. Competitive inhibition of respiration by CO occurs with Ki 2.4 muM. 6. The results are discussed in terms of the presence of three terminal oxidases in this organism, namely two oxidases with high affinities for oxygen (cytochrome c oxidase of the main phosphorylating electron-transport chain and the salicylhydroxamic acid-sensitive oxidase) and a third oxidase with a low affinity for oxygen, sensitive to inhibition by cyanide but not by azide or salicylhydroxamic acid. The relative contributions to oxygen utilization by these oxidases change during the growth of a batch culture.

BLIND SOURCE SEPARATION TECHNIQUES FOR DECOMPOSING EVENT-RELATED BRAIN SIGNALS

2004 ◽  
Vol 14 (02) ◽  
pp. 773-791 ◽  
Author(s):  
KLAUS-ROBERT MÜLLER ◽  
RICARDO VIGÁRIO ◽  
FRANK MEINECKE ◽  
ANDREAS ZIEHE
Keyword(s):  
Blind Source Separation ◽  
Source Separation ◽  
Biomedical Data ◽  
Physiological Modeling ◽  
Stability Assessment ◽  
Limited Sample ◽  
Limited Sample Size ◽  
Brain Signals ◽  
Interesting Structure

Recently blind source separation (BSS) methods have been highly successful when applied to biomedical data. This paper reviews the concept of BSS and demonstrates its usefulness in the context of event-related MEG measurements. In a first experiment we apply BSS to artifact identification of raw MEG data and discuss how the quality of the resulting independent component projections can be evaluated. The second part of our study considers averaged data of event-related magnetic fields. Here, it is particularly important to monitor and thus avoid possible overfitting due to limited sample size. A stability assessment of the BSS decomposition allows to solve this task and an additional grouping of the BSS components reveals interesting structure, that could ultimately be used for gaining a better physiological modeling of the data.

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