A Sing-Song Way of Vocalizing: Generalization and Specificity in Language and Birdsong.

Spoken languages such as German are extremely discrete, whereas others such as Portuguese are melodic or "sing-song" wherein identifying a word relies on what comes before and after. Perhaps surprisingly, birdsong also exhibits specificity and generalization as articulated by Tian and Brainard (2017)

To Tame a Songbird

Darwin was amongst the first to argue for the existence of parallels between birdsong and human language. In his book, The Descent of Man, he expresses that "the sounds uttered by birds offer in several respects the nearest analog to language." Was he right? A robust body of evidence accrued over 100 years of prolific research in birdsong endorses the claim. This dissertation is a collection of my modest efforts towards furthering this research program.In Chapter 1, I explore the evolutionary genomics of the Bengalese finch, a tame songbird frequently found in pet shops and equally popular among scientists studying learned vocal behaviors. Using whole-genome sequencing and population genomic approaches, I identify selection signals that differ between Bengalese finches and their wild munia ancestors. Findings from this study suggest that, as with mammalian domesticates, the domestication of the Bengalese finch involved a shift in selective regime, capable of altering brain circuits favoring the dynamic modulation of motivation and reward sensitivity over overall augmented aggression and stress responses. Several lines of evidence demonstrate Bengalese finches have evolved more complex vocal abilities than their wild munia ancestors: adult Bengalese finches’ song retains a greater degree of variability in the ordering of vocal elements; Bengalese finches exposed to multiple tutors compose their songs from a combination of excerpts from the different tutor’s songs, in contrast to their wild ancestors, who latch onto and copy the song of only one tutor; moreover, in cross-fostering experiments, Bengalese finches can learn a munia foster parent’s song more efficiently than munias learn their Bengalese finches foster parent’s song. In Chapter 2, I track the Bengalese finches clues into their complex abilities in vocal learning, practice, and performance. To do so, I assess gene expression patterns in song-dedicated versus more generalist brain regions of juvenile Bengalese finches actively engaged in song learning via imitation and adult individuals past this sensorimotor learning phase, and primarily engaged in song maintenance and performance to females. Results from this study uncover co-regulatory patterns involving genes essential to motivation and reward. These patterns are developmentally and behaviorally regulated in the songbird brain, and likely contribute to motor learning, practice, and performance. In Chapter 3, I take an evo-devo stance to the study of vocal learning, and examine evidence that developmental timing, though not sufficient, may have been key to the evolution of complex vocal production learning. I point out how a sort of change in evolutionary regime common to domestication practices may bring about delayed developmental trajectories; and discuss its effects on brain circuits for motivation and reward sensitivity, as they relate to vocal learnin

Caracterização molecular do gene da Arilsulfatase A em pacientes brasileiros com leucodistrofia metacromática e análise estrutural da enzima

A leucodistrofia metacromática (MLD) é um erro inato do metabolismo de herança autossômica recessiva, dividido em três subtipos clínicos de acordo com a idade de início dos sintomas. Na MLD ocorre deposição intralisossômica de glicolipídeos sulfatados principalmente no sistema nervoso central. A causa dessa doença é a deficiência de arilsulfatase A (ARSA), uma glicoproteína lisossômica que catalisa a hidrólise de glicolipídeos sulfatados constituintes da bainha de mielina. Até o momento cerca de 140 mutações relacionadas à manifestação de MLD foram descritas no gene da ARSA, das quais duas delas ocorrem com alta frequência na maioria das populações estudadas. Ademais, entre 7% e 12% das pessoas saudáveis têm deficiência in vitro de ARSA, condição denominada pseudodeficiência de ARSA (PD-ARSA). Não existem dados de caracterização genotípica de pacientes brasileiros com MLD. Da mesma forma, dados sobre a dinâmica molecular (DM) da ARSA também são escassos, em parte por dificuldades metodológicas implicadas no estudo desses aspectos em glicoproteínas. Nesse contexto, os objetivos desse trabalho foram identificar os alelos mutantes no gene da ARSA em pacientes brasileiros com MLD e avaliar os efeitos da glicosilação e do pH na DM da ARSA. A amostra foi composta por 27 pacientes com MLD. A mutação mais frequente (c.459+1G>A) e polimorfismos constituintes do alelo PD-ARSA foram detectados por PCR em tempo real e as demais mutações por sequenciamento direto do gene da ARSA. As DM realizadas foram de (i) ARSA não glicosilada em pH~7 e (ii) em pH~5, (iii) ARSA triplamente glicosilada e (iv) deficientemente glicosilada p.N350S, usando GROMACS. Nesse estudo a mutação c.459+1G>A foi a mais frequente (0,50), conforme esperado pela alta prevalência de pacientes com MLD infantil em nossa coorte. As mutações p.P426L (0,08) e c.103_110del8 (0,08) também apresentaram frequências relevantes quando comparadas às demais mutações. No conjunto, 11 mutações raras foram identificadas, incluindo 2 mutações novas: p.S44P e p.P284S. Além das mutações potencialmente deletérias, foram identificados 2 polimorfismos neutros frequentemente associados à mutação c.459+1G>A (p.W193C [0,54] e p.T391S [0,65]) e 2 polimorfismos constituintes do alelo PD-ARSA (p.N350S [0,15] e c.1524+95A>G [0,04]). As análises estruturais demonstraram um papel fundamental tanto da glicosilação, quanto do meio ácido na estabilidade da ARSA, o que é compatível com sua atividade lisossomal.Metachromatic leukodystrophy (MLD) is an inborn error of metabolism inherited in an autosomal recessive manner. MLD is a neurodegenerative condition divided into three clinical types according to age at onset of symptoms. In MLD, intralysosomal deposition of sulfated glycolipids is observed mainly in the central nervous system. The biochemical defect associated to MLD is deficiency of arylsulfatase A (ARSA), a lysosomal glycoprotein that catalyzes degradation of sulfated glycolipids found in the myelin sheet. So far, around 140 MLD-associated mutations have been identified in ARSA gene. However, two of those remain at high frequency in the majority of studied populations. In addition to MLD, in vitro ARSA deficiency is observed in approximately 7-12% of healthy population, a condition named ARSA-pseudodeficiency (ARSA-PD). Up to date, there is no available data on genotypic characterization of Brazilian MLD patients. In the same way, data on ARSA molecular dynamics (MD) are also sparse, in part due by methodological difficulties related to studies of these aspects in glycoproteins. In this context, the aims of this work were to identify mutant alleles in the ARSA gene from MLD Brazilian patients, and evaluate the effects of pH and glycosylation in ARSA MD. Sample population was composed by 27 MLD patients. The most frequent MLD-associated ARSA mutation (c.459+1G>A) and the ARSA-PD polymorphisms were detected by real-time PCR, and the remaining mutations were detected by direct sequencing of ARSA gene. The performed MD were (i) non-glycosylated ARSA at pH~7 and (ii) at pH~5, (iii) fullyglycosylated ARSA at pH~5, and (iv) poorly-glycosylated ARSA-mutant p.N350S, using GROMACS. In this study the most frequent mutation was c.459+1G>A (0.50), as expected by the high prevalence of infantile-MLD cases. Mutations p.P426L (0.08) and c.103_110del8 (0.08) were also found at relevant frequencies when compared to other mutations. In total, 11 MLD-associated rare mutations were identified, including 2 novel putative disease-causing: p.S44P and p.P284S. Besides deleterious mutations, 2 polymorphisms frequently associated with c.459+1G>A (p.W193C [0.54] and p.T391S [0.65]) and 2 polymorphisms constituents of ARSA-PD allele (p.N350S [0.15] and c.1524+95A>G [0.04]) were observed. The structural analysis demonstrated the fundamental role related to glycosylation and the acid medium in the stability of ARSA that is compatible with its lysosomal activity

A Sing-Song Way of Vocalizing: Generalization and Specificity in Language and Birdsong.

Spoken languages such as German are extremely discrete, whereas others such as Portuguese are melodic or "sing-song" wherein identifying a word relies on what comes before and after. Perhaps surprisingly, birdsong also exhibits specificity and generalization as articulated by Tian and Brainard (2017)

Birdsong as a window into language origins and evolutionary neuroscience.

Humans and songbirds share the key trait of vocal learning, manifested in speech and song, respectively. Striking analogies between these behaviours include that both are acquired during developmental critical periods when the brains ability for vocal learning peaks. Both behaviours show similarities in the overall architecture of their underlying brain areas, characterized by cortico-striato-thalamic loops and direct projections from cortical neurons onto brainstem motor neurons that control the vocal organs. These neural analogies extend to the molecular level, with certain song control regions sharing convergent transcriptional profiles with speech-related regions in the human brain. This evolutionary convergence offers an unprecedented opportunity to decipher the shared neurogenetic underpinnings of vocal learning. A key strength of the songbird model is that it allows for the delineation of activity-dependent transcriptional changes in the brain that are driven by learned vocal behaviour. To capitalize on this advantage, we used previously published datasets from our laboratory that correlate gene co-expression networks to features of learned vocalization within and after critical period closure to probe the functional relevance of genes implicated in language. We interrogate specific genes and cellular processes through converging lines of evidence: human-specific evolutionary changes, intelligence-related phenotypes and relevance to vocal learning gene co-expression in songbirds. This article is part of the theme issue What can animal communication teach us about human language

Birdsong as a window into language origins and evolutionary neuroscience.

Humans and songbirds share the key trait of vocal learning, manifested in speech and song, respectively. Striking analogies between these behaviours include that both are acquired during developmental critical periods when the brain's ability for vocal learning peaks. Both behaviours show similarities in the overall architecture of their underlying brain areas, characterized by cortico-striato-thalamic loops and direct projections from cortical neurons onto brainstem motor neurons that control the vocal organs. These neural analogies extend to the molecular level, with certain song control regions sharing convergent transcriptional profiles with speech-related regions in the human brain. This evolutionary convergence offers an unprecedented opportunity to decipher the shared neurogenetic underpinnings of vocal learning. A key strength of the songbird model is that it allows for the delineation of activity-dependent transcriptional changes in the brain that are driven by learned vocal behaviour. To capitalize on this advantage, we used previously published datasets from our laboratory that correlate gene co-expression networks to features of learned vocalization within and after critical period closure to probe the functional relevance of genes implicated in language. We interrogate specific genes and cellular processes through converging lines of evidence: human-specific evolutionary changes, intelligence-related phenotypes and relevance to vocal learning gene co-expression in songbirds. This article is part of the theme issue 'What can animal communication teach us about human language?

Effects of glycosylation and pH conditions in the dynamics of human arylsulfatase A

<div><p>Arylsulfatase A (ARSA) is a lysosomal sulfatase that catalyzes the hydrolysis of cerebroside sulfate. Its deficiency results in Metachromatic Leukodystrophy, whereas a minor condition called ARSA pseudodeficiency occurs in healthy individuals, which has been associated with the substitution of the glycosylated Asn350 by a Ser and with the loss of the polyadenylation signal. In this work, we have investigated ARSA dynamics employing molecular dynamics simulations in response to (1) different pH’s, as, beyond its natural lysossomal environment, it has been recently identified in cytoplasmatic medium and (2) glycan occupancies, including its normal glycosylation state, presenting three high mannose-type oligosaccharides. Accordingly, four systems were studied considering ARSA under different conditions: (1) nonglycosylated at pH ∼ 7 (ARSA_pH7); (2) non-glycosylated at pH ∼ 5 (ARSA_pH5); (3) triple glycosylated at pH ∼ 5 (ARSA_glyc,pH5); and (4) ARSA-N350S mutant at pH ∼ 5 (ARSA_N350S,pH5). Lowering pH and increasing glycosylation was found to reduce the flexibility of the enzyme. In addition, at acidic pH, the glycosylated enzyme presented a higher secondary conformational stability when compared to its nonglycosylated counterpart, supporting experimental findings on triple glycosylation as the essential state of ARSA. The N350S mutant exhibited a consistent degree of unfolding, which may be related to its <i>in vitro</i> reduced stability. Finally, the obtained data are discussed in the search for structural evidences able to contribute to the understanding of biological activity of ARSA and molecular etiology of ARSA pseudodeficiency, as determined by ARSA-N350S in the absence of polyadenylation defect.</p></div