Differential metabolic reprogramming in developing soybean embryos in response to nutritional conditions and abscisic acid

Seed storage compound deposition is influenced by both maternal and filial tissues. Within this framework, we analyzed strategies that operate during the development and filling of soybean embryos, using in vitro culture systems combined with metabolomics and proteomics approaches. The carbon:nitrogen ratio (C:N) of the maternal supply and the hormone abscisic acid (ABA) are specific and interacting signals inducing differential metabolic reprogrammings linked to changes in the accumulation of storage macromolecules like proteins or oils. Differences in the abundance of sugars, amino acids, enzymes, transporters, transcription factors, and proteins involved in signaling were detected. Embryos adapted to the nutritional status by enhancing the metabolism of both carbon and nitrogen under lower C:N ratio condition or only carbon under higher C:N ratio condition. ABA turned off multiple pathways especially in high availability of amino acids, prioritizing the storage compounds biosynthesis. Common responses induced by ABA involved increased sucrose uptake (to increase the sink force) and oleosin (oil body structural component) accumulation. In turn, ABA differentially promoted protein degradation under lower nitrogen supply in order to sustain the metabolic demands. Further, the operation of a citrate shuttle was suggested by transcript quantification and enzymatic activity measurements. The results obtained are useful to help define biotechnological tools and technological approaches to improve oil and protein yields, with direct impact on human and animal nutrition as well as in green chemistry.

Loss of function of Arabidopsis NADP-malic enzyme 1 results in enhanced tolerance to aluminum stress

In acidic soils, aluminum (Al) toxicity is a significant limitation to crop production worldwide. Given its Al-binding capacity, malate allows internal as well as external detoxification strategies to cope with Al stress, but little is known about the metabolic processes involved in this response. Here, we analyzed the relevance of NADP-dependent malic enzyme (NADP-ME), which catalyzes the oxidative decarboxylation of malate, in Al tolerance. Plants lacking NADP-ME1 (nadp-me1) display reduced inhibition of root elongation along Al treatment compared with the wild type (wt). Moreover, wt roots exposed to Al show a drastic decrease in NADP-ME1 transcript levels. Although malate levels in seedlings and root exudates are similar in nadp-me1 and wt, a significant increase in intracellular malate is observed in roots of nadp-me1 after long exposure to Al. The nadp-me1 plants also show a lower H₂ O₂ content in root apices treated with Al and no inhibition of root elongation when exposed to glutamate, an amino acid implicated in Al signaling. Proteomic studies showed several differentially expressed proteins involved in signal transduction, primary metabolism and protection against biotic and other abiotic stimuli and redox processes in nadp-me1, which may participate directly or indirectly in Al tolerance. The results indicate that NADP-ME1 is involved in adjusting the malate levels in the root apex, and its loss results in an increased content of this organic acid. Furthermore, the results suggest that NADP-ME1 affects signaling processes, such as the generation of reactive oxygen species and those that involve glutamate, which could lead to inhibition of root growth.

NADP-Dependent Malic Enzyme 1 Participates in the Abscisic Acid Response in Arabidopsis thaliana

Arabidopsis thaliana possesses three cytosolic (NADP-ME1-3) and one plastidic (NADP-ME4) NADP-dependent malic enzymes. NADP-ME2 and -ME4 show constitutive expression, in contrast to NADP-ME1 and -ME3, which are restricted to particular tissues. Here, we show that NADP-ME1 transcript and protein were almost undetectable during normal vegetative growth, but gradually increased and reached levels higher than those of the other isoforms in the latest stages of seed development. Accordingly, in knockout nadp-me1 mature seeds the total NADP-ME activity was significantly lower than in wild type mature seeds. The phenotypic analysis of nadp-me1 plants indicated alterations of seed viability and germination. Besides, the treatment with abscisic acid (ABA), NaCl and mannitol specifically induced the accumulation of NADP-ME1 in seedlings. In line with this, nadp-me1 plants show a weaker response of primary and lateral root length and stomatal opening to the presence of ABA. The results suggest that NADP-ME1 plays a specialized role, linked to ABA signaling during the seed development as well as in the response to water deficit stress.

The significance of HER-2 amplification and the size and type of pathological unicentric, initially operable clinical stage I and IIA/IIB breast cancer, in determining the treatment strategy

PURPOSE

In order to determine the initial treatment strategies for primary operable unicentric breast cancer, the possible relationships of the amplification of human epidermal growth-factor receptor-2 (HER-2), with age, menstrual status, tumor pathological size (pT), histopathological tumor type (HP) and kind of surgical treatment were studied.

METHODS

Analysed were 301 patients treated initially by surgery in the period 2006-2009. HP tumor type, pT and HER-2 status (using firstly immunohistochemistry and then chromogenic in situ hybridization/CISH) were determined. The patients were divided into 2 subgroups according to the presence (CISH+)/absence (CISH-) of HER-2 amplification.

RESULTS

Data on pT and HER-2 analyses were available for 293/301 (98.3%) patients with ductal (DC) and lobular carcinoma (LC). Amplification of HER-2 was found in 66 (21.9%) patients. No significant difference between the two subgroups regarding age (p=0.08), menstrual status (p>0.05) and kind of operation (p>0.05) was found. HP showed statistically significant difference between DC (55; 83.3%) and LC (11; 16.7%) patients with HER-2 amplification (p<0.01). Further HP analysis of the type of cancer within the pT category as a subgroup showed significantly higher frequency of HER-2 amplification in DC patients for pT1 (p<0.01) and in pT2 + pT3pN0 (p<0.05) compared with patients with LC.

CONCLUSION

This study showed a significantly higher incidence of HER-2 amplification in DC tumors, especially in pT1 and pT2, than in LC, which may influence the options in treatment strategies in primary unicentric operable DC type of breast cancer.

Risk factors for breast cancer: is ionizing radiation among them?

All human beings are exposed to the influence of ionizing radiation from natural, medical and other artificial sources. Therefore, the influence of radiation as a risk factor for cancer development has been among the most studied external factors over the last 6 decades, particularly with respect to radiosensitive tissues and organs. It has been known that female breast tissue is highly sensitive to the carcinogenic effects of radiation, particularly when exposure takes place at younger age. All women are exposed to low doses of radiation for several common reasons (kind of occupation, medical diagnostic procedures, residence background radiation) whose effects on breast cancer development cannot be documented, and thus it is believed that ionizing radiation is not primary or major risk factor leading to development of breast cancer. Radiobiological studies revealed a specific event caused by radiation through recognition of the critical target in radiation-induced carcinogenesis. Accordingly, mutagenic and carcinogenic effects of ionizing radiation are evidenced both in vitro and in vivo, although the incidence of radiation-induced cancers is low. The highest risk of radiation- induced breast cancer is evidenced in the sub-population of female patients who have undergone radiotherapy for either malignant or non-malignant diseases, including benign breast diseases in their childhood or young age. Therefore, as a means of prevention in this group of population, indications for application of ionizing radiation, both diagnostic and therapeutic, should be highly selective, meaning that radiation should be applied only if the possible benefit outweighs the risk.

Cooler for obtaining crystals

A design for an air cooler (`air saw') with a series of movable teeth (`modular crystallization comb') installed in a laboratory chamber furnace is presented. The setup allows easy regulation of a series of different temperature gradients, shapes of crystallization fronts and rates, in crucible columns, with the purpose of obtaining crystals. This method can also be applied in crucible or tube furnaces.

Apparatus for crystal growth

The design of an apparatus based on Bridgman's method, enabling visualization of the growth process and regulation of the crystallization rate, for obtaining single crystals from a melt in a school laboratory is presented. Conditions for obtaining single crystals of several substances are given.

Crystallization bench

An air cooler (`cold bench'), installed in a laboratory tube furnace, which allows regulation and simultaneous crystallization of several substances at different temperature gradients and rates is presented. It may be used for preparing single crystals in a school laboratory. A description of how the crystals are formed and conditions for the crystallization of some substances are given. This method can also be applied in crucible and chamber furnaces.