The D-lineage MADS-box gene OsMADS13 controls ovule identity in rice

Genes that control ovule identity were first identified in Petunia. Co-suppression of both FLORAL BINDING PROTEIN 7 (FBP7) and FBP11, two D-lineage genes, resulted in the homeotic transformation of ovules into carpelloid structures. Later in Arabidopsis it was shown that three genes, SHATTERPROOF1 (SHP1), SHP2, and SEEDSTICK (STK), redundantly control ovule identity, because in the stk shp1 shp2 triple mutant ovules lose identity and are transformed into carpel and leaf-like structures. Of these three Arabidopsis genes STK is the only D-lineage gene, and its expression, like FBP7 and FBP11, is restricted to ovules. OsMADS13 is the rice ortholog of STK, FBP7, and FBP11. Its amino acid sequence is similar to the Arabidopsis and Petunia proteins, and its expression is also restricted to ovules. We show that the osmads13 mutant is female sterile and that ovules are converted into carpelloid structures. Furthermore, making carpels inside carpels, the osmads13 flower is indeterminate, showing that OsMADS13 also has a function in floral meristem determinacy. OsMADS21 is most likely to be a paralog of OsMADS13, although its expression is not restricted to ovules. Interestingly, the osmads21 mutant did not show any obvious phenotype. Furthermore, combining the osmads13 and the osmads21 mutants did not result in any additive ovule defect, indicating that osmads21 does not control ovule identity. These results suggest that during evolution the D-lineage gene OsMADS21 has lost its ability to determine ovule identity.     

Purification and characterization of a trypsin-papain inhibitor from Pithecelobium dumosum seeds and its in vitro effects towards digestive enzymes from insect pests.

A novel trypsin-papain inhibitor, named PdKI-2, was purified from the seeds of Pithecelobium dumosum seeds by TCA precipitation, Trypsin-Sepharose chromatography and reversed-phase HPLC. PdKI-2 had an M(r) of 18.1 kDa as determined by SDS-PAGE and was composed of a single polypeptide chain. The inhibition on trypsin was stable at pH range 2-10, temperature of 50 degrees C and had a K(i) value of 1.65 x 10(-8)M, with a competitive inhibition mechanism. PdKI-2 was also active to papain, a cysteine proteinase, and showed a noncompetitive inhibition mechanism and K(i) value of 5.1 x 10(-7)M. PdKI-2 was effective against digestive proteinase from bruchids Zabrotes subfasciatus and Callosobruchus maculatus; Dipteran Ceratitis capitata; Lepidopterans Plodia interpunctella and Alabama argillacea, with 74.5%, 70.0%, 70.3%, 48.7%, and 13.6% inhibition, respectively. Results support that PdKI-2 is a member of Kunitz-inhibitor family and its effect on digestive enzyme larvae from diverse orders indicated this protein as a potent insect antifeedant.     

The Fate of Acetic Acid during Glucose Co-Metabolism by the Spoilage Yeast Zygosaccharomyces bailii

Zygosaccharomyces bailii is one of the most widely represented spoilage yeast species, being able to metabolise acetic acid in the presence of glucose. To clarify whether simultaneous utilisation of the two substrates affects growth efficiency, we examined growth in single- and mixed-substrate cultures with glucose and acetic acid. Our findings indicate that the biomass yield in the first phase of growth is the result of the weighted sum of the respective biomass yields on single-substrate medium, supporting the conclusion that biomass yield on each substrate is not affected by the presence of the other at pH 3.0 and 5.0, at least for the substrate concentrations examined. In vivo ¹³C-NMR spectroscopy studies showed that the gluconeogenic pathway is not operational and that [2−¹³C]acetate is metabolised via the Krebs cycle leading to the production of glutamate labelled on C₂, C₃ and C₄. The incorporation of [U-¹⁴C]acetate in the cellular constituents resulted mainly in the labelling of the protein and lipid pools 51.5% and 31.5%, respectively. Overall, our data establish that glucose is metabolised primarily through the glycolytic pathway, and acetic acid is used as an additional source of acetyl-CoA both for lipid synthesis and the Krebs cycle. This study provides useful clues for the design of new strategies aimed at overcoming yeast spoilage in acidic, sugar-containing food environments. Moreover, the elucidation of the molecular basis underlying the resistance phenotype of Z. bailii to acetic acid will have a potential impact on the improvement of the performance of S. cerevisiae industrial strains often exposed to acetic acid stress conditions, such as in wine and bioethanol production.     

Peripheral neuropathy in the Twitcher mouse involves the activation of axonal caspase 3

Infantile Krabbe disease results in the accumulation of lipid-raft-associated galactosylsphingosine (psychosine), demyelination, neurodegeneration and premature death. Recently, axonopathy has been depicted as a contributing factor in the progression of neurodegeneration in the Twitcher mouse, a bona fide mouse model of Krabbe disease. Analysis of the temporal-expression profile of MBP (myelin basic protein) isoforms showed unexpected increases of the 14, 17 and 18.5 kDa isoforms in the sciatic nerve of 1-week-old Twitcher mice, suggesting an abnormal regulation of the myelination process during early postnatal life in this mutant. Our studies showed an elevated activation of the pro-apoptotic protease caspase 3 in sciatic nerves of 15- and 30-day-old Twitcher mice, in parallel with increasing demyelination. Interestingly, while active caspase 3 was clearly contained in peripheral axons at all ages, we found no evidence of caspase accumulation in the soma of corresponding mutant spinal cord motor neurons. Furthermore, active caspase 3 was found not only in unmyelinated axons, but also in myelinated axons of the mutant sciatic nerve. These results suggest that axonal caspase activation occurs before demyelination and following a dying-back pattern. Finally, we showed that psychosine was sufficient to activate caspase 3 in motor neuronal cells in vitro in the absence of myelinating glia. Taken together, these findings indicate that degenerating mechanisms actively and specifically mediate axonal dysfunction in Krabbe disease and support the idea that psychosine is a pathogenic sphingolipid sufficient to cause axonal defects independently of demyelination.     

Targeting cervical cancer: Is there a role for poly (ADP-ribose) polymerase inhibition?

Patients with metastatic and recurrent cervical cancer (CC) have a poor prognosis with limited palliative treatment options. Increasing understanding of the cellular aberrations inherent to cancer cells has allowed the development of therapies to target biological pathways, an important step toward the individualization of cancer therapy. The poly (ADP-ribose) polymerase (PARP) family of enzymes is important in several DNA repair pathways. Drugs that inhibit these PARP enzymes have been investigated in many types of cancer and their application in the treatment of gynecologic malignancies has rapidly evolved. Although the majority of data for PARPi in gynecologic malignancies has been specifically regarding ovarian cancer, their role in the treatment of uterine and CC is currently being investigated. This review will examine PARP inhibitors in CC, summarizes the critical clinical trials of PARP inhibitors that have been completed, provides an overview of the on-going trials, presents the confirmed conclusions and notes the issues that need to be addressed in future studies.     

Accumulation of non-superoxide anion reactive oxygen species mediates nitrogen-limited alcoholic fermentation by Saccharomyces cerevisiae

Throughout alcoholic fermentation, nitrogen depletion is one of the most important environmental stresses that can negatively affect the yeast metabolic activity and ultimately leads to fermentation arrest. Thus, the identification of the underlying effects and biomarkers of nitrogen limitation is valuable for controlling, and therefore optimizing, alcoholic fermentation. In this study, reactive oxygen species (ROS), plasma membrane integrity, and cell cycle were evaluated in a wine strain of Saccharomyces cerevisiae during alcoholic fermentation in nitrogen-limiting medium under anaerobic conditions. The results indicated that nitrogen limitation leads to an increase in ROS and that the superoxide anion is a minor component of the ROS, but there is increased activity of both Sod2p and Cta1p. Associated with these effects was a decrease in plasma membrane integrity and a persistent cell cycle arrest at G(0)/G(1) phases. Moreover, under these conditions it appears that autophagy, evaluated by ATG8 expression, is induced, suggesting that this mechanism is essential for cell survival but does not prevent the cell cycle arrest observed in slow fermentation. Conversely, nitrogen refeeding allowed cells to reenter cell cycle by decreasing ROS generation and autophagy. Altogether, the results provide new insights on the understanding of wine fermentations under nitrogen-limiting conditions and further indicate that ROS accumulation, evaluated by the MitoTracker Red dye CM-H(2)XRos, and plasma membrane integrity could be useful as predictive markers of fermentation problems.     

Ribozymes: Analytical Solution of the One-substrate, Two-intermediate Reversible Scheme for Enzyme Reactions

The paper presents a kinetic analysis of a reversible enzymatic reaction S⇄P involving two intermediate compounds under the condition [E]₀ ≫ [S]₀ + [P]₀. For the case of mono-exponential behavior, we derive an equation for k _obs as a function of [E]₀, which emphasizes the pitfalls of oversimplifying kinetic schemes (such as the Michaelis-Menten model) for ribozyme studies. This novel apparent rate constant, which has been arrived at through mechanistic considerations, is analyzed, and the characteristic parameters obtained. The equation, which seems to fit experimental data better than conventional approximations, is used to analyze a single turnover study on an ADC1 ribozyme drawn from hepatitis delta virus RNA. The microscopic kinetic constants for such enzyme are evaluated and its mono-exponential behavior verified.     

Centennial- to decadal scale environmental shifts in and around Lake Pannon (Vienna Basin) related to a major Late Miocene lake level rise

A detailed ultra-high-resolution analysis of a 37-cm-long core of Upper Miocene lake sediments of the long-lived Lake Pannon has been performed. Despite a general stable climate at c. 11-9 Ma, several high-frequency oscillations of the paleoenvironments and depositional environments are revealed by the analysis over a short time span of less than 1000 years. Shifts of the lake level, associated with one major 3rd order flooding are reflected by all organisms by a cascade of environmental changes on a decadal scale. Within a few decades, the pollen record documents shifting vegetation zones due to the landward migration of the coast; the dinoflagellate assemblages switch towards "offshore-type" due to the increasing distance to the shore; the benthos is affected by low oxygen conditions due to the deepening. This general trend is interrupted by smaller scale cycles, which lack this tight interconnection. Especially, the pollen data document a clear cyclicity that is expressed by iterative low pollen concentration events. These "negative" cycles are partly reflected by dinoflagellate blooms suggesting a common trigger-mechanism and a connection between terrestrial environments and surface waters of Lake Pannon. The benthic fauna of the core, however, does not reflect these surface water cycles. This forcing mechanism is not understood yet but periodic climatic fluctuations are favoured as hypothesis instead of further lake level changes. Short phases of low precipitation, reducing pollen production and suppressing effective transport by local streams, might be a plausible mechanism. This study is the first hint towards solar activity related high-frequency climate changes during the Vallesian (Late Miocene) around Lake Pannon and should encourage further ultra-high-resolution analyses in the area.