The PELPIII glycoproteins in Solanaceae: stylar expression and transfer into pollen tube walls

The class III pistil-specific extensin-like proteins (PELPIII) of Nicotiana tabacum accumulate in the intercellular matrix (IM) of the style transmitting tissue (TT). After pollination, the 110–140 kDa PELPIII is translocated from the IM into the pollen tube walls. PELPIII-like sequences have been found in several solanaceous species. These sequences are expressed in mature non-pollinated styles at both RNA and protein level. Of the genus Nicotiana, the species N. alata, N. x sanderae and N. sylvestris (section Alatae), and N. tomentosiformis and N. otophora (section Tomentosae) showed an expression level of PELPIII homologues similar to that in mature styles of N. tabacum. PELPIII genes were absent in the most ancient species studied, namely N. trigonophylla (section Trigonophyllae). To study the species dependence of the translocation of PELPIII into the pollen tube wall in tobacco, interspecific pollinations on N. tabacum pistils were carried out with pollen from the incongruous species N. rustica, N. trigonophylla and Petunia hybrida, where PELPIII homologues are absent in the style. Immunocytological tests showed that the N. tabacum PELPIII is translocated into the pollen tube walls of all three species. Thus, the pollen tube walls of these species do not form a barrier for IM compounds such as the 110–140 kDa PELPIII and the absence of any possible effect of PELPIII on pollen tube growth cannot be due to failure of PELPIII transport through the wall. The importance of these findings is discussed with respect to the evolutionary origin of PELPIII, the pollen pistil interaction, the function of style TT-specific proteins and the physical properties of pollen tube walls.     

Speciation in the Artemia genus: Mitochondrial DNA analysis of bisexual and parthenogenetic brine shrimps

From the cloned mitochondrial DNAs (mtDNAs) isolated from two bisexual species, one Mediterranean, Artemia salina, and one American, Artemia franciscana, and two parthenogenetic (diploid and tetraploid) strains of Artemia parthenogenetica collected in Spain, physical maps have been constructed and compared. They are extremely different among themselves, much more than the differences between Drosophila melanogaster and D. yakuba and in the same range of different mammalian species such as mouse/rat or man/cow. The nucleotide sequences of two regions of mtDNA encoding parts of the cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) genes have been determined in the two bisexual species and the two parthenogenetic strains. Comparisons of these sequences have revealed a high degree of divergence at the nucleotide level, averaging more than 15%, in agreement with the differences found in the physical maps. The majority of the nucleotide changes are silent and there is a strong bias toward transitions, with the CT substitutions being highly predominant. The evolutionary distance between the two Artemia parthenogenetica is high and there is no clear relationship with any of the bisexual species, including the one present nowadays in Spain. Using a combination of molecular (mtDNA) and morphological markers it is possible to conclude that all of these Artemia isolates should be actually considered as belonging to different species, even the two Artemia parthenogenetica diploidica and tetraploidica.On sabbatical leave from Departamento de Bioquímica, Facultad de Veterinaria, Universidad Complutense de Madridearly Italian artemiologists to designate the Medi-Beatriz Batuecas died in an accident during the Christmas holy days of 1988 after she had initiated this workCorrespondence to: R. Garesse     

Thyrotropin and serum regulate thyroid cell proliferation through differential effects on p27 expression and localization

Thyroid cell proliferation is regulated by the concerted action of TSH/cAMP and serum growth factors. The specific contributions of cAMP-dependent vs. -independent signals to cell cycle progression are not well understood. We examined the molecular basis for the synergistic effects of TSH and serum on G1/S phase cell cycle progression in rat thyroid cells. Although strictly required for thyroid cell proliferation, TSH failed to stimulate G1 phase cell cycle progression. Together with serum, TSH increased the number of cycling cells. TSH enhanced the effects of serum on retinoblastoma protein hyperphosphorylation, cyclin-dependent kinase 2 activity, and cyclin A expression. Most notably, TSH and serum elicited strikingly different effects on p27 localization. TSH stimulated the nuclear accumulation of p27, whereas serum induced its nuclear export. Unexpectedly, TSH enhanced the depletion of nuclear p27 in serum-treated cells. Furthermore, only combined treatment with TSH and serum led to rapamycin-sensitive p27 turnover. Together, TSH and serum stimulated p70S6K activity that remained high through S phase. These data suggest that TSH regulates cell cycle progression, in part, by increasing the number of cycling cells through p70S6K-mediated effects on the localization of p27.     

Environmental assessment of Peruvian anchoveta food products: is less refined better?

Purpose

Life cycle assessments (LCAs) of various anchovy (anchoveta) direct human consumption products processed in Peru were carried out, to evaluate their relative environmental performance as alternative products to enhance nutrition of communities with low access to fish products in the country.

Methods

LCA was carried out for fresh, frozen, canned, salted and cured anchoveta products, both at plant gate and featuring local and national distribution over non-refrigerated, chilled and fully refrigerated distribution chain. The functional unit used was 1 kg of fish in the final product.

Results and discussion

Results demonstrate that, in environmental terms, more-refined products (cured and canned anchoveta products) represent a much higher burden than less- refined products (fresh, frozen and salted). Although this is a likely result, the magnitude of this difference (4 to 27 times when expressed as an environmental single score) is higher than expected and had not been quantified before for salted and cured products, as far as we know. This difference is mainly due to differences in energy consumption between types of products. Furthermore, cured and salted products feature larger biotic resource use, when calculated based on the whole fish equivalent, due to higher processing losses/discards. The relevance of taking into account the different transportation and storage needs is highlighted. For those products requiring refrigerated transportation and storage, over a national distribution chain, those activities increase the overall environmental impacts of the products by 55 % (fresh chilled) to 67 % (frozen). However, such an increase does not worsen the environmental performance of fresh and frozen products in comparison to the energy-intensive canned and cured products.

Conclusions

It is concluded that a more sustainability-oriented analysis, including the social and economic pillars of sustainability, is required towards decision-making involving promotion of either product for addressing nutritional deficiencies in Peru.     

Mesure in vivo de la radioactivite thyroïdienne apres injection d'iode radioactif 131I chez les colombides

Résumé La mesure précise in vivo de l'iode radioactif fixé par la thyroïde du Pigeon en fonction du temps après injection de ¹³¹I est délicate, en raison, d'une part, de la position anatomique de la thyroïde, d'autre part, de la masse des tissus juxtathyroïdiens, dont la radioactivité interfère avec celle de la glande.Nous avons conu un appareil de contention, qui, en immobilisant l'animal non anesthésié, permet de placer et de maintenir la glande dans une position identique par rapport au compteur, lors de chaque mesure.La radioactivité des tissus juxtathyroïdiens est évaluée à partir de celle d'une zone abdominale bien déterminée.La reproductibilité des mesures de radioactivité dans la zone thyroïdienne est comparable à celles d'autres méthodes d'étude in vivo chez les Mammifères. L'erreur effectuée sur la mesure de la radioactivité thyroïdienne, exprimée en % de la dose injectée, est en moyenne de 10%.     

A step ahead: combining protein purification and correct folding selection

The success of recombinant protein expression seems unpredictable and even good yields of soluble proteins do not guarantee the correct folding. The search for soluble constructs can be performed by exploiting libraries and speeded up by automation, but these approaches are money and time consuming and the tags used for affinity purification can mask the real stability of the target proteins. The ideal purification protocol would include the structure quality control. A recent paper commented in this article describes a phage-display method to screen for antibodies that are able to re-fold after heat-denaturation and can be selectively affinity-purified only if monodispersed. It turned out that the proteins with high recovery performance after heat-shock were also suitable for efficient recombinant expression.     

Mutant casein kinase I (Hrr25p/Kti14p) abrogates the G1 cell cycle arrest induced by <Emphasis Type="Italic"> Kluyveromyces lactis </Emphasis>zymocin in budding yeast

Zymocin, a toxic protein complex produced by Kluyveromyces lactis, inhibits cell cycle progression in Saccharomyces cerevisiae. In studying its action, a resistant mutant ( kti14-1) was found to express the tot-phenotype typical of totDelta cells, toxin target (TOT) mutants that are impaired in RNA polymerase II Elongator function. Phenotypic analysis of a kti14-1 tot3Delta double mutant revealed a functional link between KTI14 and TOT/Elongator. Unlike totDelta cells, the kti14-1 mutant is sensitive to the drug methylmethane sulfonate (MMS), indicating that, besides being affected in TOT function, kti14-1 cells are also compromised in DNA repair. Single-copy complementation identified HRR25, which codes for casein kinase I (CKI), as KTI14. Kinase-minus hrr25 mutations (K38A and T176I) conferred zymocin resistance, while deletion of the other yeast CKI genes ( YCK1-3) had no effect. A mutation in KTI14 that truncates the P/Q-rich C-terminus of Hrr25p also dissociates MMS sensitivity from zymocin resistance; this mutant is resistant to the toxin, but shows normal sensitivity to MMS. Thus, although kinase-minus mutations are sufficient to protect yeast cells from zymocin, toxicity is also dependent on the integrity of the C-terminal region of Hrr25p, which has been implicated in determining the substrate specificity or localization of Hrr25p.