Role of a telencephalic nucleus in the delayed song learning of socially isolated zebra finches

Male zebra finches normally learn their song from adult models during a restricted period of juvenile development. If song models are not available then, juveniles develop an isolate song which can be modified in adulthood. In this report we investigate the features of juvenile experience that underly the timing of song learning. Juvenile males raised in soundproof chambers or in visual isolation from conspecifics developed stable isolate song. However, whereas visual isolate song notes were similar to those of colony-reared males, soundproof chamber isolates included many phonologically abnormal notes in their songs. Despite having stable isolate songs, both groups copied new notes from tutors presented to them in adulthood (2.7 notes per bird for soundproof chamber isolates, 4.4 notes per bird for visual isolates). Old notes were often modified or eliminated. We infer that social interactions with live tutors are normally important for closing the sensitive period for song learning. Lesions of a forebrain nucleus (IMAN) had previously been shown to disrupt juvenile song learning, but not maintenance of adult song for up to 5 weeks after surgery. In this study, colony-reared adult males given bilateral lesions of IMAN retained all their song notes for up to 4–7.5 months after lesioning. However, similar lesions blocked all song note acquisition in adulthood by both visual and soundproof chamber isolates. Other work has shown that intact hearing is necessary for the maintenance of adult zebra finch song. We infer that auditory pathways used for song maintenance and acquisition differ: IMAN is necessary for auditorily guided song acquisition—whether by juveniles or adults—but not for adult auditorily guided song maintenance. © 1993 John Wiley & Sons, Inc.     

Epigenetic and pharmacological control of pigmentation via Bromodomain Protein 9 (BRD9)

Lineage-specific differentiation programs are activated by epigenetic changes in chromatin structure. Melanin-producing melanocytes maintain a gene expression program ensuring appropriate enzymatic conversion of metabolites into the pigment, melanin, and transfer to surrounding cells. During neuroectodermal development, SMARCA4 (BRG1), the catalytic subunit of SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complexes, is essential for lineage specification. SMARCA4 is also required for development of multipotent neural crest precursors into melanoblasts, which differentiate into pigment-producing melanocytes. In addition to the catalytic domain, SMARCA4 and several SWI/SNF subunits contain bromodomains which are amenable to pharmacological inhibition. We investigated the effects of pharmacological inhibitors of SWI/SNF bromodomains on melanocyte differentiation. Strikingly, treatment of murine melanoblasts and human neonatal epidermal melanocytes with selected bromodomain inhibitors abrogated melanin synthesis and visible pigmentation. Using functional genomics, iBRD9, a small molecule selective for the bromodomain of BRD9 was found to repress pigmentation-specific gene expression. Depletion of BRD9 confirmed a requirement for expression of pigmentation genes in the differentiation program from melanoblasts into pigmented melanocytes and in melanoma cells. Chromatin immunoprecipitation assays showed that iBRD9 disrupts the occupancy of BRD9 and the catalytic subunit SMARCA4 at melanocyte-specific loci. These data indicate that BRD9 promotes melanocyte pigmentation whereas pharmacological inhibition of BRD9 is repressive.     

Membrane inlet—ion mobility spectrometry with automatic spectra evaluation as online monitoring tool for the process control of microalgae cultivation

The cultivation of algae either in open raceway ponds or in closed bioreactors could allow the renewable production of biomass for food, pharmaceutical, cosmetic, or chemical industries. Optimal cultivation conditions are however required to ensure that the production of these compounds is both efficient and economical. Therefore, high-frequency analytical measurements are required to allow timely process control and to detect possible disturbances during algae growth. Such analytical methods are only available to a limited extent. Therefore, we introduced a method for monitoring algae release volatile organic compounds (VOCs) in the headspace above a bioreactor in real time. This method is based on ion mobility spectrometry (IMS) in combination with a membrane inlet (MI). The unique feature of IMS is that complete spectra are detected in real time instead of sum signals. These spectral patterns produced in the ion mobility spectrum were evaluated automatically via principal component analysis (PCA). The detected peak patterns are characteristic for the respective algae culture; allow the assignment of the individual growth phases and reflect the influence of experimental parameters. These results allow for the first time a continuous monitoring of the algae cultivation and thus an early detection of possible disturbances in the biotechnological process.     

In vitro oxygen consumption and motility of Cryptobia salmositica, Cryptobia bullocki, and Cryptobia catostomi (Sarcomastigophora: Kinetoplastida).

Cryptobia salmositica (pathogenic and vaccine strains), Cryptobia bullocki (pathogenic), and Cryptobia catostomi (nonpathogenic) have similar oxygen consumption rates (0.17 +/- 0.01 nm O2/10(6) parasites). Incubation with sodium azide (5 microliters of a 1-M solution to 1 ml of parasite suspension, i.e., a 5-mM final concentration) reduced the oxygen consumption by approximately 4.5-fold. Motility of the parasites was also greatly reduced in sodium azide. The oxygen consumption and motility of the parasites returned to preazide treatment levels when the azide was removed even after 24 hr of incubation in sodium azide. The activities of hexokinase, pyruvate kinase, and cytochrome C oxidase were not detected in the 3 species of Cryptobia.     

Calcitonin-like immunoreactivity in the blue crab: tissue distribution, variations in the molt cycle, and partial characterization.

Calcitonin-like immunoreactivity has been found in blood and tissues of the marine blue crab, Callinectes sapidus Rathbun. The activity in blood rises significantly during the immediate premolt (D4) stage, but tissue immunoreactivity does not vary significantly with molt stage. The immunoreactivity to antisalmon calcitonin serum is due to a 27.2 kDa protein that shows strong similarities in amino acid composition to a similar protein in a lobster and to human calcitonin precursor. The protein is most abundant in the midgut glands (hepatopancreas), but is also found in significant quantities in several other tissues. Immunoreactivity in the blood appears to be primarily due to the same molecular weight fraction, with secondary contributions from smaller molecules, closer in size to vertebrate calcitonin. A physiological function of the calcitonin-like substance in calcium transport during or after molt has yet to be demonstrated.     

Expression of the Saccharomyces cerevisiae Kex2p endoprotease in inset cells. Evidence for a carboxy-terminal autoprocessing event.

The pheromone-processing Kex2p endoprotease of Saccharomyces cerevisiae has been difficult to characterize due to its low level of expression in yeast cells. To overcome this problem, we have overexpressed Kex2p using the baculovirus/insect cell expression system. Spodoptera frugiperda Sf9 insect cells infected with a recombinant baculovirus, containing the complete KEX2 gene which encodes the Kex2p protease (814 amino acids), accumulate an 120-kDa functional form of the enzyme. The inhibition profile of the insect-cell-derived endoprotease is similar to that of the yeast enzyme. The recombinant infected insect cells also secrete into the medium about half of the total Kex2p activity produced. Deleting the carboxyl-terminal tail and the transmembrane domain of Kex2p (Kex2 delta p, 666 amino acids) does not measurably interfere with the enzyme characteristics and results in the secretion of up to 90% of the total enzyme activity. The truncated form, Kex2 delta p, of the endoprotease accumulates in the cell supernatant to 6.7 x 10(5) U/l. The molecular mass of the secreted forms for both the wild-type Kex2p and Kex2 delta p is the same (70 kDa) and is 50-kDa lower than the intracellular form. This result implicates a processing event which gives rise to shorter extracellular forms of both the wild-type Kex2p and Kex2 delta p and which trims their carboxy termini upsteam of amino acid 666. This processing event requires the integrity of the Ser385 of the Kex2p active site.