Space bioreactors: their use,their future

The use of bioreactors during space flight is discussed. The major elements of a bioreactor are a culture chamber, sensors, a control unit with feedback, as gas exchange system, a pump, fresh culture medium, and a waste reservoir. Types of bioreactors developed for use in space include the Woodlawn Wanderer 9 apparatus, the Space tissue loss system, rotating wall vessel, dynamic cell culture system and the SBR I. Future development for space bioreactors include improvements for cultivation of mammalian cells and tissue engineering and the transfer of bioreactor technology for earth-bound instruments.     

By the teeth of their skin, cavefish find their way

Teeth and skin teeth (denticles), collectively named odontodes, are usually associated with the physical roles of cutting, protection or drag reduction in fishes [1,2]. These structures are composed of a soft pulp surrounded by dentine and covered by a mineralized substance such as enamel [3]. Odontodes arise from neural crest cells and epithelium and are often innervated [1-3]. However, little is known about their possible sensory function. Here, we demonstrate for the first time a mechanosensory role for denticles in a cavefish endemic to a fast water flow cave. All fishes gather hydrodynamic information via specialized sense organs called neuromasts [4-6]. Some fishes are especially attentive to such type of information [5] and until now hypertrophy of the neuromast system has been reported as the main constructive sensory adaptation in cavefishes [6,7]. We expect that the mechanosensory nature of denticles highlighted in this cave fish species might reflect a widespread sensory role for these structures in other animals.     

Honeybees change their height to restore their optic flow

To further elucidate the mechanisms underlying insects’ height and speed control, we trained outdoor honeybees to fly along a high-roofed tunnel, part of which was equipped with a moving floor. Honeybees followed the stationary part of the floor at a given height. On encountering the moving part of the floor, which moved in the same direction as their flight, honeybees descended and flew at a lower height, thus gradually restoring their ventral optic flow (OF) to a similar value to that they had percieved when flying over the stationary part of the floor. This was therefore achieved not by increasing their airspeed, but by lowering their height of flight. These results can be accounted for by a control system called an optic flow regulator, as proposed in previous studies. This visuo-motor control scheme explains how honeybees can navigate safely along tunnels on the sole basis of OF measurements, without any need to measure either their speed or the clearance from the surrounding walls.     

Rapid Quantification of Phototrophic Microorganisms and their Physiological State through their Colour

Quantification of phototrophic organisms on solid substrata together with their metabolic activity can be assessed easily, reliably and quickly through measurement of the organisms' colour. For that purpose only a chroma meter for solid substrata able to quantify the three components of colour is needed. A correlation between these three components and the number of organisms and their physiological state was demonstrated. The methodology developed here makes it possible to save time and materials in comparison with traditional microbiological methods. Moreover, it is a non-destructive method which can be used directly on site and in site. This characteristic is important when microbial environmental monitoring of cultural heritage is involved.     

Specific interactions of serpins in their native forms attenuate their conformational transitions

Plasminogen activator inhibitor-1 (PAI-1) belongs to the serine protease inhibitor (serpin) protein superfamily. Serpins are unique in that their native forms are not the most thermodynamically stable conformation; instead, a more stable, latent conformation exists. During the transition to the latent form, the first strand of beta-sheet C (s1C) in the serpin is peeled away from the beta-sheet, and the reactive center loop (RCL) is inserted into beta-sheet A, rendering the serpin inactive. To elucidate the contribution of specific interactions in the metastable native form to the latency transition, we examined the effect of mutations at the s1C of PAI-1, specifically in positions P4' through P10'. Several mutations strengthened the interactions between these residues and the core protein, and slowed the transition of the protein from the metastable native form to the latent form. In particular, anchoring of the strand to the protein's hydrophobic core at the beginning (P4' site) and center of the strand (P8' site) greatly retarded the latency transition. Mutations that weakened the interactions at the s1C region facilitated the conformational conversion of the protein to the latent form. PAI-1's overall structural stability was largely unchanged by the mutations, as evaluated by urea-induced equilibrium unfolding monitored via fluorescence emission. Therefore, the mutations likely exerted their effects by modulating the height of the energy barrier from the native to the latent form. Our results show that interactions found only in the metastable native form of serpins are important structural features that attenuate folding of the proteins into their latent forms.     

Yeast killer toxins,molecular mechanisms of their action and their applications

Killer toxins secreted by some yeast strains are the proteins that kill sensitive cells of the same or related yeast genera. In recent years, many new yeast species have been found to be able to produce killer toxins against the pathogenic yeasts, especially Candida albicans. Some of the killer toxins have been purified and characterized, and the genes encoding the killer toxins have been cloned and characterized. Many new targets including different components of cell wall, plasma membrane, tRNA, DNA and others in the sensitive cells for the killer toxin action have been identified so that the new molecular mechanisms of action have been elucidated. However, it is still unknown how some of the newly discovered killer toxins kill the sensitive cells. Studies on the killer phenomenon in yeasts have provided valuable insights into a number of fundamental aspects of eukaryotic cell biology and interactions of different eukaryotic cells. Elucidation of the molecular mechanisms of their action will be helpful to develop the strategies to fight more and more harmful yeasts.     

Orangutans modify their gestural signaling according to their audience's comprehension

When people are not fully understood, they persist with attempts to communicate, elaborating their speech in order to better convey their meaning [1]. We investigated whether captive orangutans (Pongo pygmaeus and Pongo abelii) would use analogous communicative strategies in signaling to a human experimenter, and whether they could distinguish different degrees of misunderstanding. Orangutans' behavior varied according to how well they had apparently been understood. When their aims were not met, they persisted in communicative attempts. However, when the interlocutor appeared partially to understand their meaning, orangutans narrowed down their range of signals, focusing on gestures already used and repeating them frequently. In contrast, when completely misunderstood, orangutans elaborated their range of gestures, avoiding repetition of failed signals. It is therefore possible, from communicative signals alone, to determine how well an orangutan's intended goal has been met. This differentiation might function under natural conditions to allow an orangutan's intended goals to be understood more efficiently. In the absence of conventional labels, communicating the fact that an intention has been somewhat misunderstood is an important way to establish shared meaning.     

Visual discrimination of cues differing as for their number of elements, their shape or their orientation, by the ant Myrmica sabuleti

Using operant conditioning as a method, we study if Myrmica sabuleti workers can discriminate figures made of different numbers of the same element, different filled shapes or hollow forms and elements differently oriented. The ants effectively discriminate figures containing different numbers of the same element but without counting the elements: their distinguishing is based on the global aspect (dimensions, area) of the figures. They distinguish filled shapes as well as hollow forms when these look different if seen with convexity. For instance, they differentiate well between concave filled shapes or concave hollow forms. They see distinctly an element and the same one rotated if this element, seen with convexity, looks different after its rotation. They perceive until a 30° rotation of a vertical segment and until a 15° rotation of a horizontal segment. In conclusion, M. sabuleti workers are sensitive to the number of elements, dimension, shape, form and orientation of visual cues with the restriction that they probably see them with convexity.     

Switchable DNA-origami nanostructures that respond to their environment and their applications

Structural DNA nanotechnology, in which Watson-Crick base pairing drives the formation of self-assembling nanostructures, has rapidly expanded in complexity and functionality since its inception in 1981. DNA nanostructures can now be made in arbitrary three-dimensional shapes and used to scaffold many other functional molecules such as proteins, metallic nanoparticles, polymers, fluorescent dyes and small molecules. In parallel, the field of dynamic DNA nanotechnology has built DNA circuits, motors and switches. More recently, these two areas have begun to merge—to produce switchable DNA nanostructures, which change state in response to their environment. In this review, we summarise switchable DNA nanostructures into two major classes based on response type: molecular actuation triggered by local chemical changes such as pH or concentration and external actuation driven by light, electric or magnetic fields. While molecular actuation has been well explored, external actuation of DNA nanostructures is a relatively new area that allows for the remote control of nanoscale devices. We discuss recent applications for DNA nanostructures where switching is used to perform specific functions—such as opening a capsule to deliver a molecular payload to a target cell. We then discuss challenges and future directions towards achieving synthetic nanomachines with complexity on the level of the protein machinery in living cells.     

Semisynthetic epsilon-isorhodomycins: their synthesis using glycals and their structure-activity relationship

Syntheses and structure-activity relationships of 7-O-(3-amino-2,3,6-trideoxy-a-L-lyxo- (18), -L-arabino- (20) and -L-ribo- hexopyranosyl)-epsilon-isorhodomycins (25) and their 3'-dimethylamino derivatives 22, 23 and 26 are described. Condensation (trimethylsilyl triflate, molecular sieves 4 A, 10:1 dichloromethane-acetone, -15 degrees) of epsilon-isorhodomycinone (epsilon-isoRMN, 6) with 1,5-anhydro-4-O-p-nitrobenzoyl-3-trifluoroacetamido-L-lyxo- (5) -L-arabino- (9) or -L-ribo-hex-l-enitols (10) afforded mainly the 7-O-a-glycosyl-epsilon-isoRMNs 7, 11, and 12. Similar glycosylation of 6 with 1,5-anhydro-3-azido-4-O-p-nitrobenzoyl-2,3,6-trideoxy-L-arabino-hex-1-++ +enitol (15) yielded a-glycoside 16. Removal (M NaOH) of the p-nitrobenzoyl and trifluoroacetyl groups from 7, 11, and 12 gave the 7-O-(3-amino-2,3,6-trideoxy-a-L-hexopyranosyl)-epsilon-isoRMNs 18, 20, and 25. Reductive alkylation (CH2O, NaCNBH3) of these products afforded the 3'-N,N-dimethyl analogues 22, 23, and 26. The cytotoxic effect (IC50) of the semisynthetic epsilon-isorhodomycins was tested in vitro in leukemia cell line L1210.     

Plastids unleashed: their development and their integration in plant development

Derived by endosymbiosis from ancestral cyanobacteria, chloroplasts integrated seamlessly into the biology of their host cell. That integration involved a massive transfer of genes to the cell's nucleus, with the modification of pre-existing processes, like plastid division and the operation of the plastid genetic machinery and the emergence of new ones, like the import of proteins translated in the cytoplasm. The uncovering in molecular detail of several of these processes reveals a merger of mechanisms of symbiont and host origin. Chloroplasts acquired roles as part of the biology of land plants by differentiating into a variety of interconvertible plastid forms according to the cell type. How these conversions take place, or how new problems, like the regulation of the plastid population size in cells, have been solved, is barely starting to be understood. Like the whole plant and as a result of the requirements and dangers associated with photosynthetic activity, chloroplasts in particular are under the control of environmental cues. Far from being passive targets of cellular processes, plastids are sources of signals of plastid-nuclear communication, which regulate activities for their own biogenesis. Plastids are also sources of developmental signals, in whose absence tissue architecture or cell differentiation are aberrant, in a cell-autonomous fashion. Over evolutionary time, plastids also contributed many genes for activities that are no longer directly associated with them (like light perception or hormone function). The overall picture is one in which plastids are at both the receiving and the acting ends in plant development, in both ontogenic and evolutionary terms.     

Anabolic steroids: a review of their effects on the muscles, of their possible mechanisms of action and of their use in athletics.

Anabolic steroids are synthetic molecules developed in the hope of obtaining a complete separation of the androgenic and myotrophic (anabolic) actions of testosterone. Such a goal has never been fully achieved. However, some synthetic steroids present a partial dissociation between these two activities. Since a single hormonal receptor apparently mediates the androgenic as well as the anabolic actions of testosterone, differences in patterns of androgen metabolization in the muscles and the sex accessory organs have been proposed as a possible cause of this phenomenon. Undoubtedly, androgens are able to exert a trophic effect on skeletal and cardiac muscle fibres in subjects with low circulating levels of testosterone such as prepubertal or hypogonadal males and females; however, the widespread use of anabolic steroids in male athletes to increase their physical performances poses the question of whether these compounds are active in the presence of normal circulating levels of testosterone. Most experimental animal studies indicate that anabolic steroids are ineffective in this situation. Since the results of the experiments performed in humans are largely contradictory, it is still not clear whether anabolic steroids are able to improve athletic performances. These and other relevant issues are reviewed.     

Environmental specialists: their prevalence and their influence on community-similarity analyses

Recent research suggests that environmental or habitat specialization among plants may be less common than previously thought. These findings need to be reconciled with interpretations of community‐level similarity analyses that emphasize a strong role for specialization. Here we examine specialization within a taxonomic group that, owing to their widespread use as environmental indicators, should provide ample supportive evidence of specialization: freshwater sediment diatoms. Using an ideal, 239‐lake survey data set that reliably represents the environmental conditions among c. 9500 north‐eastern US lakes (encompassing a c. 405 000 km² region), we show that only 29 and 14% of 401 species (those occurring in at least two lakes) exhibited narrower pH and total phosphorus niche breadths, respectively, than expected from the random occupation of lakes. These rates increase slightly using more stringent species‐inclusion criteria. Highly significant correlations between compositional and environmental resemblance matrices are shown to reflect a balance between a strong signal generated by the minority specialists, and noise generated by the majority generalists.     

Changes in the communities of Paleozoic brachiopods due to their development of their filtering system

Onward changes in the communities of Paleozoic articulated brachiopods were mainly connected with the improvement of the function of their filter feeding system, which is responsible for the feeding of animals. Three major routes of improvement are known: (1) feeding using a primitive lophophore and specialized mantle (orders Strophomenida, Chonetida, and Productida); (2) increased complexity and enlargement of the spirolophe and the appearance of the spiral brachidium (orders Atrypida, Spiriferida, and Athyridida); (3) development of the protective structures preventing ingestible particles into the inner cavity of the shell (order Rhynchonellida). The most effective was the third variant that allowed rhynchonellids, which appeared in the Ordovician, to live up to recently and survive after two largest extinctions in the history of the group development: in the Late Devonian and at the Permian-Triassic boundary.     

Chemical components of ginseng,their biotransformation products and their potential as treatment of hypertension

Molecular and Cellular Biochemistry - Ginseng is an ancient perennial herb belonging to the family Araliaceae and genus Panax which has been used for medical therapeutics for thousands of years,...