Influence of phosphorus concentration on the growth kinetics and stoichiometry of the microalga Scenedesmus obliquus

The growth of the freshwater microalga Scenedesmus obliquus was studied at 30°C in a mineral culture medium with phosphorus concentrations of between 0 and 372 μ . The values for the specific growth rates, between and , fitted a semistructured substrate-limitation model with μ_m1 = 0·0466 h⁻¹, μ_m2 = 0·0256 h⁻¹ and . The specific uptake rate of phosphorus reached a maximum value of q_Sm1 = 658·01 × 10⁻⁴ μmol P mg⁻¹ biomass h⁻¹.     

The calcium‐dependent protein kinase CPK7 acts on root hydraulic conductivity

The hydraulic conductivity of plant roots (Lp_r) is determined in large part by the activity of aquaporins. Mechanisms occurring at the post‐translational level, in particular phosphorylation of aquaporins of the plasma membrane intrinsic protein 2 (PIP2) subfamily, are thought to be of critical importance for regulating root water transport. However, knowledge of protein kinases and phosphatases acting on aquaporin function is still scarce. In the present work, we investigated the Lp_r of knockout Arabidopsis plants for four Ca²⁺‐dependent protein kinases. cpk7 plants showed a 30% increase in Lp_r because of a higher aquaporin activity. A quantitative proteomic analysis of wild‐type and cpk7 plants revealed that PIP gene expression and PIP protein quantity were not correlated and that CPK7 has no effect on PIP2 phosphorylation. In contrast, CPK7 exerts a negative control on the cellular abundance of PIP1s, which likely accounts for the higher Lp_r of cpk7. In addition, this study revealed that the cellular amount of a few additional proteins including membrane transporters is controlled by CPK7. The overall work provides evidence for CPK7‐dependent stability of specific membrane proteins.     

Regeneration of multiple shoots from transgenic potato events facilitates the recovery of phenotypically normal lines: assessing a cry9Aa2 gene conferring insect resistance

Background

Tools for authenticating cell lines are critical for quality control in cell-based biological experiments. Currently there are methods to authenticate human cell lines using short tandem repeat (STR) markers based on the technology and procedures successfully used in the forensic community for human identification, but there are no STR based methods for authenticating nonhuman cell lines to date. There is significant homology between the human and vervet monkey genome and we utilized these similarities to design the first multiplex assay based on human STR markers for vervet cell line identification.

Results

The following STR markers were incorporated into the vervet multiplex PCR assay: D17S1304, D5S1467, D19S245, D1S518, D8S1106, D4S2408, D6S1017, and DYS389. The eight markers were successful in uniquely identifying sixty-two vervet monkey DNA samples and confirmed that Vero76 cells and COS-7 cells were derived from Vero and CV-1 cells, respectively. The multiplex assay shows specificity for vervet DNA within the determined allele range for vervet monkeys; however, the primers will also amplify human DNA for each marker resulting in amplicons outside the vervet allele range in several of the loci. The STR markers showed genetic stability in over sixty-nine passages of Vero cells, suggesting low mutation rates in the targeted STR sequences in the Vero cell line.

Conclusions

A functional vervet multiplex assay consisting of eight human STR markers with heterozygosity values ranging from 0.53-0.79 was successful in uniquely identifying sixty-two vervet monkey samples. The probability of a random match using these eight markers between any two vervet samples is approximately 1 in 1.9 million. While authenticating a vervet cell line, the multiplex assay may also be a useful indicator for human cell line contamination since the assay is based on human STR markers.     

A New Species of Allosathes Gaud, Atyeo & Berla (Astigmata: Crypturoptidae) on Feathers of the Chilean Tinamou, Nothoprocta perdicaria (Tinamiformes: Tinamidae) in Chile

Allosathes anitae n. sp. Casanueva & González-Acu?a (Astigmata: Crypturoptidae), collected on the Chilean tinamou Nothoprocta perdicaria (Tinamiformes: Tinamidae) from different localities of the ?uble Province, Chile, is described. Comments on its affinities and differences with Allosathes anepiandrius Gaud, Atyeo & Berla are also included.     

TRAINING NEEDS ASSESSMENT IN RESEARCH ETHICS EVALUATION AMONG RESEARCH ETHICS COMMITTEE MEMBERS IN THREE AFRICAN COUNTRIES: CAMEROON,MALI AND TANZANIA

Background: As actors with the key responsibility for the protection of human research participants, Research Ethics Committees (RECs) need to be competent and well‐resourced in order to fulfil their roles. Despite recent programs designed to strengthen RECs in Africa, much more needs to be accomplished before these committees can function optimally. Objective: To assess training needs for biomedical research ethics evaluation among targeted countries. Methods: Members of RECs operating in three targeted African countries were surveyed between August and November 2007. Before implementing the survey, ethical approvals were obtained from RECs in Switzerland, Cameroon, Mali and Tanzania. Data were collected using a semi‐structured questionnaire in English and in French. Results: A total of 74 respondents participated in the study. The participation rate was 68%. Seventy one percent of respondents reported having received some training in research ethics evaluation. This training was given by national institutions (31%) and international institutions (69%). Researchers and REC members were ranked as the top target audiences to be trained. Of 32 topics, the top five training priorities were: basic ethical principles, coverage of applicable laws and regulations, how to conduct ethics review, evaluating informed consent processes and the role of the REC. Conclusion: Although the majority of REC members in the targeted African countries had received training in ethics, they expressed a need for additional training. The results of this survey have been used to design a training program in research ethics evaluation that meets this need.     

Oligomerization of the voltage-gated proton channel

The voltage-gated proton channel exists as a dimer, although each protomer has a separate conduction pathway, and when forced to exist as a monomer, most major functions are retained. However, the proton channel protomers appear to interact during gating. Proton channel dimerization is thought to result mainly from coiled-coil interaction of the intracellular C-termini. Several types of evidence are discussed that suggest that the dimer conformation may not be static, but is dynamic and can sample different orientations. Zn²⁺ appears to link the protomers in an orientation from which the channel(s) cannot open. A tandem WT-WT dimer exhibits signs of cooperative gating, indicating that despite the abnormal linkage, the correct orientation for opening can occur. We propose that C-terminal interaction functions mainly to tether the protomers together. Comparison of the properties of monomeric and dimeric proton channels speaks against the hypothesis that enhanced gating reflects monomer-dimer interconversion.Key words: voltage-gated proton channels, voltage gating, voltage-sensing domains, phagocytes, coiled-coil, oligomerization, proton currents, pH, dimerization, C-terminus     

Molecular phylogenetic evidence that the phylum Haplosporidia has an alveolate ancestry

The phylogenetic position of the phylum Haplosporidia among other protists was investigated with the complete 16S-like rRNA gene sequences from two species in the phylum: Haplosporidium nelsoni, a parasite of oysters, and Minchinia teredinis, a parasite of shipworms. Because the lack of obvious morphological homologies with other protists hampered decisions regarding taxonomic composition for sequence alignment and phylogenetic analysis, the complete sequences for these two haplosporidians were directed as search queries to the blast/ncbi.nlm.nih.gov electronic mail server. The results of this heuristic similarity search provided a basis for constructing a preliminary higher-taxonomic-level analysis comparing the haplosporidians with species from the slime molds, fungi, algae, amoebae, ciliates, dinoflagellates, and apicomplexans. Maximum parsimony yielded equivocal results, whereas transversionally weighted parsimony suggested an affinity with the alveolates (i.e., the ciliates, dinoflagellates, and apicomplexans). Multiple alignment of the two haplosporidian sequences against 17 taxa in a secondary analysis focusing on the alveolates and subsequent parsimony analysis placed the phylum Haplosporidia as a monophyletic group within the Alveolata and as a taxon of equal rank with the other three alveolate phyla. The precise placement within the Alveolata was sensitive to weighting.