Ultrastructure of differentiating epidermal cells of maize root under water deficit conditions

The ultrastructure of differentiating epidermal cells of maize root (within the distance of 1 and 2 mm from the root body apex) were studied under conditions of non-lethal and lethal osmotic stresses of nutrient medium containing polyethylene glycol 4000, as well as regeneration of their ultrastructure following rehydration. The structural response to water deficit of the cells investigated was dependent on both the stress duration and the stage of their ontogenic development. Following non-lethal stress, in younger cells investigated (1 mm), condensation of nuclear chromatin, decrease of polyribosomes and increased density of free ribosomes in cytoplasm, reduction of mitochondrial cristae and occurrence of intramitochondrial inclusions, less compact dictyosomes were observed. Pastid structure remained unchanged. Microtubules were lacking in treated cells. In the more differentiated cells (2 mm) protoplast retreat from cell walls was also observed as well as a general decrease of ribosomes and ER elements in parietal cytoplasm, an increased number of intramitochondrial inclusions and mitochondrial membrane fragmentation. In these cells, Golgi apparatus was also lacking. The ultrastructure regeneration of the more differentiated cells was less pronounced. Lethal osmotic stress would cause more severe structural damage in all the cell components investigated.     

Aposematism and mimicry in soft‐bodied beetles of the superfamily Cleroidea (Insecta)

The evolution of animal life strategies is among the main themes of current evolutionary biology. Checkered beetles, soft‐winged flower beetles and their allies (superfamily Cleroidea), exhibit well‐known aposematic colour patterns, particularly in the family Cleridae, which participate in mimicry complexes mostly with unpalatable beetles, ants and velvet ants representing a Müllerian–Batesian continuum. Many cleroids also exhibit attenuated hardening of cuticular layers resulting in a soft‐bodied appearance. Here, a molecular phylogenetic analysis of the entire Cleroidea was performed using sequences of two nuclear and two mitochondrial loci of ~4 kb total length. Inferred phylogenies were used to reconstruct ancestral colour patterns and involvement in mimicry complexes. The hypothesis of a soft‐bodied ancestor of Cleridae and allies was tested. The phylogenetic analyses corroborated the expanded Cleroidea concept including Byturidae and Biphyllidae formerly classified as Cucujoidea. Character state optimization showed cryptic coloration was the ancestral state in Cleroidea, from which aposematic coloration originated several times in distant cleroid lineages. Within Cleridae, mimicry also arose from an ancestor that was cryptic, and multiple lineages that mimicked unpalatable beetles (Chrysomelidae, Meloidae, Lycidae) and stinging Hymenoptera evolved. Aposematic coloration was acquired in all major clerid lineages including Thanerocleridae, which are either the sister group of Chaetosomatidae or Cleridae. These findings suggest that mimetic traits in the clerid clade evolved at various times, possibly soon after the origin of soft‐bodiedness. The adaptive value of aposematism in cleroids is likely to be enhanced in soft‐bodied species, as this trait provides limited means of protection against predators, and therefore may promote the acquisition of aposematic and mimetic coloration in various ecological situations.     

Predation on a wild Philippine tarsier (Tarsius syrichta)

Little is known about predation on the Philippine tarsier. Only one other case of predation, probably by a cat, has previously been reported. In our study, we present two events of predation, one on a female tarsier by a water monitor lizard, another on an infant tarsier by an unknown predator. We also describe the behaviour of the tarsier mother after losing her infant. Our observations extend current knowledge about predation pressure on the Philippine tarsier.     

Cellular responses of two Latin-American cultivars of Lotus corniculatus to low pH and Al stress

Toxic effects of acidic root medium and aluminium were evaluated in two forage cultivars of Lotus corniculatus differing in their tolerance to Al stress. The structural response of most of the root cells exposed to low pH without Al³⁺ differed markedly from that induced by the combined stress. Conspicuous alteration of the nucleus was present only at low pH 4.0 and disintegration of the cytoplasmic components was more drastic than in the roots exposed to acidic solution containing Al³⁺. Cells exposed to low pH without Al, did not produce wall thickenings. Severely damaged cytoplasm and localized death in some cortical cells or groups of cells contrasting with almost intact cells exposed to Al³⁺ stress were found. In this respect, a strong correlation between the occurrence of cell wall thickenings and a better preserved structure of the cytoplasm was observed. The frequency of cell damage in the more tolerant cultivar UFRGS was generally lower, significantly more cortical cells capable of maintaining their resting membrane potential were present than in the sensitive INIA Draco. The difference in their tolerance is related rather to the exudation of citrate and oxalate that was higher in UFRGS than to the accumulation of tannins, which increased after Al treatment in both cultivars.     

Small non-coding RNA profiling in breast cancer: plasma U6 snRNA,miR-451a and miR-548b-5p as novel diagnostic and prognostic biomarkers

Molecular Biology Reports - Breast cancer is a leading cause of cancer-related death in women. Most cases are invasive ductal carcinomas of no special type (NST breast carcinomas). In this...