Molecular mapping of movement-associated areas in the avian brain: a motor theory for vocal learning origin

Vocal learning is a critical behavioral substrate for spoken human language. It is a rare trait found in three distantly related groups of birds-songbirds, hummingbirds, and parrots. These avian groups have remarkably similar systems of cerebral vocal nuclei for the control of learned vocalizations that are not found in their more closely related vocal non-learning relatives. These findings led to the hypothesis that brain pathways for vocal learning in different groups evolved independently from a common ancestor but under pre-existing constraints. Here, we suggest one constraint, a pre-existing system for movement control. Using behavioral molecular mapping, we discovered that in songbirds, parrots, and hummingbirds, all cerebral vocal learning nuclei are adjacent to discrete brain areas active during limb and body movements. Similar to the relationships between vocal nuclei activation and singing, activation in the adjacent areas correlated with the amount of movement performed and was independent of auditory and visual input. These same movement-associated brain areas were also present in female songbirds that do not learn vocalizations and have atrophied cerebral vocal nuclei, and in ring doves that are vocal non-learners and do not have cerebral vocal nuclei. A compilation of previous neural tracing experiments in songbirds suggests that the movement-associated areas are connected in a network that is in parallel with the adjacent vocal learning system. This study is the first global mapping that we are aware for movement-associated areas of the avian cerebrum and it indicates that brain systems that control vocal learning in distantly related birds are directly adjacent to brain systems involved in movement control. Based upon these findings, we propose a motor theory for the origin of vocal learning, this being that the brain areas specialized for vocal learning in vocal learners evolved as a specialization of a pre-existing motor pathway that controls movement.     

Endocochlear potential depends on Cl- channels: mechanism underlying deafness in Bartter syndrome IV

Human Bartter syndrome IV is an autosomal recessive disorder characterized by congenital deafness and severe renal salt and fluid loss. It is caused by mutations in BSND, which encodes barttin, a beta-subunit of ClC-Ka and ClC-Kb chloride channels. Inner-ear-specific disruption of Bsnd in mice now reveals that the positive potential, but not the high potassium concentration, of the scala media depends on the presence of these channels in the epithelium of the stria vascularis. The reduced driving force for K(+)-entry through mechanosensitive channels into sensory hair cells entails a profound congenital hearing loss and subtle vestibular symptoms. Although retaining all cell types and intact tight junctions, the thickness of the stria is reduced early on. Cochlear outer hair cells degenerate over several months. A collapse of endolymphatic space was seen when mice had additionally renal salt and fluid loss due to partial barttin deletion in the kidney. Bsnd(-/-) mice thus demonstrate a novel function of Cl(-) channels in generating the endocochlear potential and reveal the mechanism leading to deafness in human Bartter syndrome IV.     

Overlap of the gene encoding the novel poly(ADP-ribose) polymerase Parp10 with the plectin 1 gene and common use of exon sequences

We have recently identified PARP10 as a novel functional poly(ADP-ribose) polymerase. The gene encoding PARP10 is conserved in vertebrates but no orthologs were found in lower organisms. In addition to the poly(ADP-ribose) polymerase domain, PARP10 possesses several additional sequence motifs, including an RNA recognition motif and two ubiquitin interaction motifs. We characterized the murine genomic locus of the Parp10 gene. We noticed that 3' Parp10 sequences overlapped with the plectin 1 gene in a head-to-tail arrangement. Detailed analyses revealed that the two most 3' Parp10 exons (exons 10 and 11) are also used for plectin 1. While these two exons code for part of the poly(ADP-ribose) polymerase domain in Parp10, they are noncoding for plectin 1 due to the lack of appropriate start codons. Furthermore our findings suggest that at least one of the plectin 1 promoters is located within intron 9 of the Parp10 gene.     

Stimulation of c-MYC transcriptional activity and acetylation by recruitment of the cofactor CBP

The c-MYC oncoprotein regulates various aspects of cell behaviour by modulating gene expression. Here, we report the identification of the cAMP-response-element-binding protein (CBP) as a novel c-MYC binding partner. The two proteins interact both in vitro and in cells, and CBP binds to the carboxy-terminal region of c-MYC. Importantly, CBP, as well as p300, is associated with E-box-containing promoter regions of genes that are regulated by c-MYC. Furthermore, c-MYC and CBP/p300 function synergistically in the activation of reporter-gene constructs. Thus, CBP and p300 function as positive cofactors for c-MYC. In addition, c-MYC is acetylated in cells. This modification does not require MYC box II, suggesting that it is independent of TRRAP complexes. Instead, CBP acetylates c-MYC in vitro, and co-expression of CBP with c-MYC stimulates in vivo acetylation. Functionally, this results in a decrease in ubiquitination and stabilization of c-MYC proteins. Thus, CBP and p300 are novel functional binding partners of c-MYC.     

Purification of recombinantly expressed human cluster determinant 4 cytoplasmic domain

A DNA fragment coding for the human CD4 cytoplasmic domain (residues 394-433) was cloned into the pET15b expression vector. The resulting plasmid was used for synthesis of the polyhistidine-tagged 5.10(3) M(r) CD4 peptide in Escherichia coli BL21(DE3)Star. The CD4 cytoplasmic domain was purified under denaturing and reducing conditions by a two-step procedure using immobilized metal affinity chromatography and gel permeation chromatography. The purified CD4 cytoplasmic domain is soluble and functional without any specific refolding steps. The yield of the described purification procedure was approximately 5 mg peptide per liter culture volume.     

Forestry Influence by Stump Harvest and Site Preparation on Methylmercury, Total Mercury and Other Stream Water Chemistry Parameters Across a Boreal Landscape

Forestry has been reported to cause elevated mercury (Hg) concentrations in runoff water. However, the degree to which forestry operations influence Hg in runoff varies among sites. A synoptic study, covering 54 catchments distributed all over Sweden, subjected to either stump harvest (SH), site preparation (SP) or no treatment (Ref), was undertaken to reveal the degree of forestry impact and causes of eventual variation. All streams were sampled twice, in autumn 2009 and summer 2010. There were no significant differences in total mercury (THg) and methylmercury (MeHg) concentrations between the three treatments in either 2009 or 2010. However, when pooling the treated catchments (that is, SH and SP) and taking catchment properties such as latitude into account, the treatment had a significant influence on the THg and MeHg concentrations. Although the treatment effect on THg and MeHg did not differ between SH and SP, the study did reveal significant forestry effects on potassium (K) and total nitrogen (TN) that were greater in the SH catchments and lower in the SP catchments. Partial least square (PLS) regressions indicated that organic matter was the most important variable influencing both the THg and MeHg concentrations. There were no significant differences between the treatment groups when comparing the ratios of THg/total organic carbon (TOC) and MeHg/TOC, suggesting that the high concentrations of THg and MeHg observed at some of the treated catchments are associated with increased concentrations of TOC rather than new methylation or increased mobilization caused by factors other than TOC.     

Immunodetection of cyclooxygenase-2 (COX-2) is restricted to tissue macrophages in normal rat liver and to recruited mononuclear phagocytes in liver injury and cholangiocarcinoma

It has been suggested that cyclooxygenase-2 (COX-2)-mediated prostaglandin synthesis is associated with liver inflammation and carcinogenesis. The aim of this study is to identify the cellular source of COX-2 expression in different stages, from acute liver injury through liver fibrosis to cholangiocarcinoma (CC). We induced in rats acute and “chronic” liver injury (thioacetamide (TAA) or carbon tetrachloride (CCl₄)) and CC development (TAA) and assessed COX-2 gene expression in normal and damaged liver tissue by RT-PCR of total RNA. The cellular localization of COX-2 protein in liver tissue was analyzed by immunohistochemistry as well as in isolated rat liver cells by Western blotting. The findings were compared with those obtained in human cirrhotic liver tissue. The specificity of the antibodies was tested by 2-DE Western blot and mass spectrometric identification of the positive protein spots. RT-PCR analysis of total RNA revealed an increase of hepatic COX-2 gene expression in acutely as well as “chronically” damaged liver. COX-2-protein was detected in those ED1⁺/ED2⁺ cells located in the non-damaged tissue (resident tissue macrophages). In addition COX-2 positivity in inflammatory mononuclear phagocytes (ED1⁺/ED2⁻), which were also present within the tumoral tissue was detected. COX-2 protein was clearly detectable in isolated Kupffer cells as well as (at lower level) in isolated “inflammatory” macrophages. Similar results were obtained in human cirrhotic liver. COX-2 protein is constitutively detectable in liver tissue macrophages. Inflammatory mononuclear phagocytes contribute to the increase of COX-2 gene expression in acute and chronic liver damage induced by different toxins and in the CC microenvironment.     

Warmer and browner waters decrease fish biomass production

Climate change studies have long focused on effects of increasing temperatures, often without considering other simultaneously occurring environmental changes, such as browning of waters. Resolving how the combination of warming and browning of aquatic ecosystems affects fish biomass production is essential for future ecosystem functioning, fisheries, and food security. In this study, we analyzed individual‐ and population‐level fish data from 52 temperate and boreal lakes in Northern Europe, covering large gradients in water temperature and color (absorbance, 420 nm). We show that fish (Eurasian perch, Perca fluviatilis) biomass production decreased with both high water temperatures and brown water color, being lowest in warm and brown lakes. However, while both high temperature and brown water decreased fish biomass production, the mechanisms behind the decrease differed: temperature affected the fish biomass production mainly through a decrease in population standing stock biomass, and through shifts in size‐ and age‐distributions toward a higher proportion of young and small individuals in warm lakes; brown water color, on the other hand, mainly influenced fish biomass production through negative effects on individual body growth and length‐at‐age. In addition to these findings, we observed that the effects of temperature and brown water color on individual‐level processes varied over ontogeny. Body growth only responded positively to higher temperatures among young perch, and brown water color had a stronger negative effect on body growth of old than on young individuals. Thus, to better understand and predict future fish biomass production, it is necessary to integrate both individual‐ and population‐level responses and to acknowledge within‐species variation. Our results suggest that global climate change, leading to browner and warmer waters, may negatively affect fish biomass production, and this effect may be stronger than caused by increased temperature or water color alone.