Stable transformation of Mesembryanthemum crystallinum (L.) with Agrobacterium rhizogenes harboring the green fluorescent protein targeted to the endoplasmic reticulum

Stable transformation of Mesembryanthemum crystallinum L. (common ice plant) with a green fluorescent protein (GFP) construct targeted to the endoplasmic reticulum was obtained. Seven and fourteen days after germination seedlings were infected with Agrobacterium rhizogenes strain ARqua1 either by direct coating of the cut radicles with bacteria growing on solid medium or by immersion of the cut surface in bacterial suspension at different optical densities. Both methods of infection resulted in production of GFP-positive roots with a frequency ranging from 6 to 20% according to the age of the explants and the application procedure. The green fluorescing roots displayed the typical hairy root phenotype and were easily maintained in liquid medium without growth regulators for over 2 years. Stable expression of the transgene in the roots was confirmed by polymerase chain reaction (PCR), immunoblotting and the capacity of roots to grow and produce callus on kanamycin-enriched medium. Nineteen endogenous cytokinins were determined in transgenic and non-transformed roots. The results revealed significantly lower levels of the free bases of isopentenyladenine, dihydrozeatin, cis- and trans-zeatin, as well as a conspicuous decline in concentrations of the corresponding nucleosides and most nucleotides in transgenic roots compared to the wild type. Comparison of the cytokinin profiles in transgenic and non-transformed roots suggested that transformation by A. rhizogenes disturbed cytokinin metabolism during the early steps of biosynthesis. Calli obtained from transformed roots were GFP-positive and remained non-regenerative or displayed high rhizogenic potential depending on the auxin/cytokinin ratio in the medium. Calli and callus-derived roots showed a strong GFP signal for over 2 years.     

C-fos gene activation in murine thymocytes by a mechanism independent of protein kinase C or a Ca2+ signal

The accumulation of c-fos mRNA in mouse thymocytes was compared when the cells were stimulated by concanavalin A (Con A), the Ca2+ ionophore A23187 or the phorbol ester, TPA, either separately or by combinations of these mitogens. The c-fos response to mitogenic concentrations of Con A could not be attributed either to the rise in [Ca2+]i it induces or to activation of protein kinase C. Thus, although Con A causes the breakdown of phosphatidylinositol 4,5-bisphosphate in these cells, neither of the signals which can be generated by this response was responsible for the activation of the c-fos gene by Con A. This implies that some other unidentified signal generated by Con A activates the c-fos gene.     

Social behavior of a marmoset (Saguinus fuscicollis) group I: Parental care and infant development

Development was observed as three infant sets were born into a semi-naturalistic family group. Data on infant carrying through 12 weeks of age revealed that, at almost every week, the father carried more than the mother, and the males carried more than the females. Spatial data for the first two infant sets showed nearest neighbor distances supporting a two-stage proximity process during development. Behavioral data for 30 weeks were rather variable between the first two infant sets; this suggests that infant behavioral patterns may be more dependent upon the composition of the group than is spatial development or infant carrying. Incidents of “play fathering» and the importance of parental care and infant development in general were discussed.     

Reversible coupling of glucoenzymes on fluoride-sensitive FET biosensors based on lectin-glucoprotein binding

New reloadable biosensors were developed by affinity binding of glucoenzymes peroxidase and glucose oxidase on pF-sensitive field-effect transistors (Si/SiO₂/Si₃N₄/LaF₃ layers). The basic measuring principle of these ion sensitive field-effect transistors is the current change depending on the concentration of F⁻ ions. The immobilized glucoenzymes can be removed from the enzymatically inactive Concanavalin A basic membrane and fresh enzymes can be bound again. The principle of this reloadable biosensor is described in detail. Additionally, the biosensor was successfully integrated in a flow-injection analysis system for measuring glucose during a cultivation process.     

Climate sensitivity across marine domains of life: limits to evolutionary adaptation shape species interactions

Organisms in all domains, Archaea, Bacteria, and Eukarya will respond to climate change with differential vulnerabilities resulting in shifts in species distribution, coexistence, and interactions. The identification of unifying principles of organism functioning across all domains would facilitate a cause and effect understanding of such changes and their implications for ecosystem shifts. For example, the functional specialization of all organisms in limited temperature ranges leads us to ask for unifying functional reasons. Organisms also specialize in either anoxic or various oxygen ranges, with animals and plants depending on high oxygen levels. Here, we identify thermal ranges, heat limits of growth, and critically low (hypoxic) oxygen concentrations as proxies of tolerance in a meta‐analysis of data available for marine organisms, with special reference to domain‐specific limits. For an explanation of the patterns and differences observed, we define and quantify a proxy for organismic complexity across species from all domains. Rising complexity causes heat (and hypoxia) tolerances to decrease from Archaea to Bacteria to uni‐ and then multicellular Eukarya. Within and across domains, taxon‐specific tolerance limits likely reflect ultimate evolutionary limits of its species to acclimatization and adaptation. We hypothesize that rising taxon‐specific complexities in structure and function constrain organisms to narrower environmental ranges. Low complexity as in Archaea and some Bacteria provide life options in extreme environments. In the warmest oceans, temperature maxima reach and will surpass the permanent limits to the existence of multicellular animals, plants and unicellular phytoplankter. Smaller, less complex unicellular Eukarya, Bacteria, and Archaea will thus benefit and predominate even more in a future, warmer, and hypoxic ocean.     

Small brains, bright minds

Learning, memory, and social behavior are innate properties of the honeybee that are essential for the survival of each individual as well as for the survival of the hive. The small, accessible brain of the honeybee and the availability of the complete sequence of its genome make this social insect an ideal model for studying the connection between learning, memory, and social behavior.