Polyethylene microplastics alter root functionality and affect strawberry plant physiology and fruit quality traits.

Strawberry, a globally popular crop whose fruit are known for their taste and health benefits, were used to evaluate the effects of polyethylene microplastics (PE-MPs) on plant physiology and fruit quality. Plants were grown in 2-L pots with natural soil mixed with PE-MPs at two concentrations (0.2% and 0.02%; w/w) and sizes (⌀ 35 and 125 µm). Plant physiological responses, root histochemical and anatomical analyses as well as fruit biometric and quality features were conducted. Plants subjected to ⌀ 35 µm/0.2% PE-MPs exhibited the most severe effects in terms of CO2 assimilation due to stomatal limitations, along with the highest level of oxidative stress in roots. Though no differences were observed in plant biomass, the impact on fruit quality traits was severe in ⌀ 35 µm/0.2% MPs treatment resulting in a drop in fruit weight (-42%), soluble solid (-10%) and anthocyanin contents (-25%). The smallest sized PE-MPs, adsorbed on the root surface, impaired plant water status by damaging the radical apparatus, which finally resulted in alteration of plant physiology and fruit quality. Further research is required to determine if these alterations also occur with other MPs and to understand more deeply the MPs influence on fruit physio-chemistry.

Impact of TiO2 nanoparticles on Vicia narbonensis L.: potential toxicity effects.

This work was aimed to provide further information about toxicology of TiO2 nanoparticles (NPs) on Vicia narbonensis L., considering different endpoints. After exposure to TiO2 nanoparticle suspension (mixture of rutile and anatase, size <100 nm) at four different concentrations (0.2, 1.0, 2.0 and 4.0 ‰), the seeds of V. narbonensis were let to germinate in controlled environmental conditions. After 72 h, the extent of the success of the whole process (seed germination plus root elongation) was recorded as the vigour index, an indicator of possible phytotoxicity. After the characterisation of the hydric state of different materials, oxidative stress and enzymatic and nonenzymatic antioxidant responses were considered as indicators of possible cytotoxicity and to assess if damage induced by TiO2 NPs was oxidative stress-dependent. Cytohistochemical detection of in situ DNA fragmentation as genotoxicity endpoint was monitored by TUNEL reaction. The treatments with TiO2 NPs in our system induced phytotoxic effects, ROS production and DNA fragmentation. The nonenzymatic and enzymatic antioxidant responses were gradually and differentially activated and were able to maintain the oxidative damage to levels not significantly different from the control. On the other hand, the results of DNA fragmentation suggested that the mechanisms of DNA repair were not effective enough to eliminate early genotoxicity effects.

Response to a plaque control regimen on different levels of gingival inflammation.

BACKGROUND: The purpose of the present study was to evaluate the effectiveness of an oral hygiene regimen in subjects presenting with substantially different severity of plaque-associated gingivitis. METHODS: The study population was selected from among a large pool of subjects undergoing an experimental gingivitis trial. At completion of the 21-day plaque accumulation period, 2 sub-groups of subjects were identified on the basis of uppermost and lowest quartile for Gingival Index (GI), respectively classified as highly-inflamed (Hinf; n=17; GI: 1.07+/-0.10) and slightly-inflamed (Sinf; n=22; GI: 0.28+/-0.09) groups. An oral hygiene regimen, based on use of amine fluoride/stannous fluoride-containing toothpaste and mouthrinse, was then prescribed for 21 days. RESULTS: Plaque Index (PI), GI, gingival crevicular fluid (GCF) and Angulated Bleeding Index (AngBI) significantly decreased after treatment in both HInf and SInf groups (p<0.001). However, PI (0.77+/-0.41 vs 0.43+/-0.33, p<0.01), GI (0.23+/-0.30 vs 0.08+/-0.11, p<0.05), GCF (15.23 +/-7.11 vs 7.66+/-2.93, p<0.0000) remained significantly greater in the Hinf group compared to the Sinf group. CONCLUSIONS: These results suggest that 1) an oral hygiene regimen based on amine/stannous fluoride-containing toothpaste and mouthrinse is effective in reducing plaque-associated gingivitis, regardless of pre-existing severity of gingival inflammation; 2) the level of improvement in gingival status, however, is dependent on the pre-existing severity of the inflammatory condition.

Formation of p27-CDK complexes during the human mitotic cell cycle.

In eukaryotic cells, the coordinated activation of different cyclin-dependent kinases regulates entry into S-phase. In vitro and in nonproliferating cells, p27 associates with and inhibits cyclin/cycin-dependent kinase (CDK) holoenzymes containing either CDK4, CDK6, or CDK2. Although many different types of proliferating cells contain p27 protein, neither the interactions of p27 with cyclin/CDK complexes nor the consequences of this interaction during the mitotic cycle have been fully explored. We report that, in MANCA cells, the amount of p27 is constant during the cell cycle. In addition, p27 associates with three different CDKs: CDK2, CDK4, and CDK6. Furthermore, the amount of p27 is significantly lower than the amount of cyclin D3 in these cells. The amount of CDK4 and CDK6 associated with p27 does not change in a cell cycle-dependent fashion; in contrast, the amount of CDK2 associated with p27 is lowest in early G1 cells and increases to a maximum in mid-G1 phase, reaching a steady-state level in late G1-phase cells. After mid-G1 phase, the amount of each p27/CDK complex remains constant through the remainder of the cell cycle. p27-immunoprecipitates contain an Rb-kinase activity. The substrate specificity, the expression pattern of this kinase, and the ability to deplete 50% of this kinase activity with a CDK6-specific antibody suggest that the CDK6 protein mediates, in part, the p27-associated Rb-kinase activity. In contrast, p27 complexes containing CDK2 are incapable of phosphorylating histone H1. These data are consistent with a model wherein cyclin D/CDK complexes sequester the CDK2-dependent kinase inhibitory activity of p27.

Gas2, a growth arrest-specific protein, is a component of the microfilament network system.

In this report we analyze the protein product of a growth arrest-specific gene, gas2, by means of an affinity-purified antibody raised against the protein produced in bacteria. The regulation of Gas2 biosynthesis reflects the pattern of mRNA expression (Schneider, C., R. King, and L. Philipson. 1988. Cell. 54:787-793): its relative level is tightly associated with growth arrest. Gas2 seems to be regulated also at the posttranslational level via a phosphorylation mechanism. Gas2 is well conserved during the evolution with the same apparent molecular mass (36 kD) between mouse and human. We also demonstrate that Gas2 is a component of the microfilament system. It colocalizes with actin fiber, at the cell border and also along the stress fiber, in growth-arrested NIH 3T3 cells. The pattern of distribution, detected in arrested cells, can also be observed in growing cells when they are microinjected with the purified GST-Gas2 protein. In none of the analyzed oncogene-transformed NIH 3T3 cell lines was Gas2 expression induced under serum starvation.