Characterization, developmental expression and evolutionary features of the huntingtin gene in the amphioxus Branchiostoma floridae

<p>Abstract</p> <p>Background</p> <p>Huntington's disease is an inherited neurodegenerative disorder that is caused by the expansion of an N-terminal polyQ stretch in the huntingtin protein. In order to investigate the hypothesis that huntingtin was already involved in development of the nervous system in the last common ancestor of chordates, we isolated and characterised the huntingtin homologue from the amphioxus <it>Branchiostoma floridae</it>. In the present paper the amphioxus general term must be referred to <it>Branchiostoma floridae</it>.</p> <p>Results</p> <p>In this report, we show that the exon-intron organization of the amphioxus huntingtin gene is highly conserved with that of other vertebrates species. The AmphiHtt protein has two glutamine residues in the position of the typical vertebrate polyQ tract. Sequence conservation is greater along the entire length of the protein than in a previously identified <it>Ciona </it>huntingtin. The first three N-terminal HEAT repeats are highly conserved in vertebrates and amphioxus, although exon rearrangement has occurred in this region. <it>AmphiHtt </it>expression is detectable by in situ hybridization starting from the early neurula stage, where it is found in cells of the neural plate. At later stages, it is retained in the neural compartment but also it appears in limited and well-defined groups of non-neural cells. At subsequent larval stages, <it>AmphiHtt </it>expression is detected in the neural tube, with the strongest signal being present in the most anterior part.</p> <p>Conclusion</p> <p>The cloning of amphioxus huntingtin allows to infer that the polyQ in huntingtin was already present 540 million years ago and provides a further element for the study of huntingtin function and its evolution along the deuterostome branch.</p

Huntingtin gene evolution in Chordata and its peculiar features in the ascidian Ciona genus

BACKGROUND: To gain insight into the evolutionary features of the huntingtin (htt) gene in Chordata, we have sequenced and characterized the full-length htt mRNA in the ascidian Ciona intestinalis, a basal chordate emerging as new invertebrate model organism. Moreover, taking advantage of the availability of genomic and EST sequences, the htt gene structure of a number of chordate species, including the cogeneric ascidian Ciona savignyi, and the vertebrates Xenopus and Gallus was reconstructed. RESULTS: The C. intestinalis htt transcript exhibits some peculiar features, such as spliced leader trans-splicing in the 98 nt-long 5' untranslated region (UTR), an alternative splicing in the coding region, eight alternative polyadenylation sites, and no similarities of both 5' and 3'UTRs compared to homologs of the cogeneric C. savignyi. The predicted protein is 2946 amino acids long, shorter than its vertebrate homologs, and lacks the polyQ and the polyP stretches found in the the N-terminal regions of mammalian homologs. The exon-intron organization of the htt gene is almost identical among vertebrates, and significantly conserved between Ciona and vertebrates, allowing us to hypothesize an ancestral chordate gene consisting of at least 40 coding exons. CONCLUSION: During chordate diversification, events of gain/loss, sliding, phase changes, and expansion of introns occurred in both vertebrate and ascidian lineages predominantly in the 5'-half of the htt gene, where there is also evidence of lineage-specific evolutionary dynamics in vertebrates. On the contrary, the 3'-half of the gene is highly conserved in all chordates at the level of both gene structure and protein sequence. Between the two Ciona species, a fast evolutionary rate and/or an early divergence time is suggested by the absence of significant similarity between UTRs, protein divergence comparable to that observed between mammals and fishes, and different distribution of repetitive elements

Studi limnologici sul bacino del Lago di Candia. Attivit? 2009

No abstract availabl

Analisi della relazione tra le concentrazione di azoto e la composizione delle comunit? acquatiche

This report presents an analysis of the relationships between environmental variables and organisms belonging to the four biotic communities used to define the lake\u27s ecological quality, according to provisions of the Italian legislation (D.Lgs. 260, November 2010) and the European Water Framework 2000/6. The data analyzed were collected during the sampling surveys carried out within InHabit Project in 13 water bodies, 7 in Piedmont and 6 in Sardinia respectively. In particular, the aim of the study was to evaluate the possible effects of nitrogen on biotic communities. Phytoplankton community shown the clearer responses: according to the result of multivariate analysis, total nitrogen and ammonium nitrogen are among the most significant factors explaining the relationships among phytoplankton orders, species and environmental variables. In particular, cyanobacteria increased considerably with increasing availability of ammonium nitrogen. Conversely, high concentrations of this compound suppress the development of diatoms. Other algal groups show a nonlinear response with respect to nitrogen, with a possible limitation under low levels of nitrogen and an inhibition at higher levels. A comparative analysis, carried out to evaluate the response to the gradient of total phosphorus, shows that this nutrient is not as selective as nitrogen in controlling the structure of the algal assemblage in different environmental conditions. Other biotic communities did not show a clear relationship with nitrogen, but they rather responded to the trophic gradient as a whole: responses by macroinvertebrates seem, especially in the analysis of functional groups, complex and difficult to discriminate, highlighting a possible shifting of the food web towards the presence of large carnivores at high trophic status. Regarding the fish, the results show that nitrogen alone does not seem to be an important controlling factor for the fish communities. However together with the phosphorus, is one of the main elements controlling both biomass and size of the fish fauna, as well as the presence of tolerant, omnivorous or benthofagous species. In conclusion, the results of our analysis highlight the need for a greater emphasis on nitrogen inputs, which, especially in cases of nitrogen carried by atmospheric deposition, may even affect lake ecosystems relatively distant from direct impacts of human activities, thus altering the structure of biotic communities.A partire dai dati raccolti con le campagne di campionamento effettuate nell?ambito del progetto InHabit, questo documento presenta un?analisi delle relazioni tra le variabili ambientali e gli organismi appartenenti alle quattro comunit? biotiche utilizzate per la definizione della qualit? ecologica degli ambienti lacustri, secondo quanto previsto dal D.Lgs. 260 del novembre 2010, che recepisce la Direttiva Europea sulle Acque 2000/60. I campionamenti sono stati condotti in 13 ambienti lacustri, 7 in Piemonte e 6 in Sardegna. In particolare, lo scopo del lavoro ? stato valutare i possibili effetti sulla comunit? biotiche di concentrazioni variabili dei composti azotati inclusi tra le variabili considerate. La comunit? che mostra le risposte pi? chiare ? quella fitoplanctonica: come risulta dall?analisi multivariata, sia azoto ammoniacale che azoto totale compaiono tra le variabili significative per spiegare l?ordinamento di ordini e specie fitoplanctoniche. Tra questi, sono soprattutto i cianobatteri che aumentano sensibilmente all?aumentare della disponibilit? di azoto ammonicale. Al contrario, elevate concentrazioni di questo composto deprimono lo sviluppo delle diatomee. Altri gruppi algali mostrano una risposta non lineare rispetto ai composti azotati, con una possibile limitazione a bassi livelli di azoto ed una inibizione a livelli troppo elevati. L?analisi della risposta rispetto al gradiente di fosforo totale, mostra che questo nutriente non ? selettivo come l?azoto nel controllare la struttura delle associazioni algali in diverse condizioni ambientali. Le altre comunit? non hanno mostrato una relazione evidente con i composti azotati, ma, piuttosto, con il gradiente trofico complessivo: le risposte evidenziate dalla fauna macroinvertebrata, sembrano, soprattutto nell?analisi dei gruppi funzionali, complesse e difficili da discriminare, evidenziando un possibile spostamento degli equilibri della rete trofica verso i carnivori in presenza di elevati livelli trofici. Relativamente alla fauna ittica, i risultati mostrano che da solo l?azoto non sembra essere un fattore di controllo importante per la comunit? ittiche. Tuttavia insieme al fosforo, ? uno degli elementi principali a cui si associano positivamente la biomassa e le dimensioni della fauna ittica, nonch? la presenza di specie tolleranti, onnivore o bentofaghe. In conclusione, i risultati della nostra analisi, sottolineano ulteriormente la necessit? di porre una maggiore attenzione agli apporti di azoto, che, soprattutto nei casi di azoto veicolato da deposizioni atmosferiche, potrebbero interessare anche ecosistemi lacustri relativamente distanti da impatti diretti delle attivit? antropiche, alterandone la struttura delle comunit? biotiche

Effetti dell\u27inquinamento da azoto nei laghi e nei fiumi e suggerimento per il miglioramento dei PdG

This report summarizes the finding of the InHabit project on the importance of atmospheric nitrogen deposition in affecting the chemical composition of lake water and in eventually altering the biological communities living in them. Previous deliverables (I2d5, Id26 and I2d7) have shown that; 1. in both regions studied in the InHabit project (Piedmont and Sardinia), atmospheric deposition of nitrogen compounds is relevant; 2. the flux of nitrogen from the atmosphere to the ecosystem is markedly larger in Piedmont than in Sardinia; 3. models of the dynamic behavior of nitrogen in forested catchments indicates that Piedmon soils are mainly N-saturated, so that nitrogen carried by atmospheric deposition can be released form forest soil to the surface water; 4. in Sardinia, soil are less saturated, but a part of the deposited nitrogen is still carried to surface water; 5. trend analysis of deposition and stream water revealed that nitrogen deposition is stable or slightly decreasing in recent years, both in atmospheric deposition and in stream water; 6. the importance relative importance of N deposition is relevant for sites in or close to reference conditions; 7. the relationships between environmental variables and organisms belonging to the four biotic communities used to define the lake\u27s ecological quality, according to provisions of the Italian legislation (D.Lgs. 260, November 2010) and the European Water Framework 2000/60 differ depending on the biological quality element considered; 8. phytoplankton community shows the clearer responses: according to the result of multivariate analysis, total nitrogen and ammonium nitrogen are among the most significant factors explaining the relationships among phytoplankton orders, species and environmental variables. In particular, cyanobacteria increased considerably with increasing availability of ammonium nitrogen. Conversely, high concentrations of this compound suppress the development of diatoms. On the basis of those results, which are summarized in this deliverable, we focused on the effect of different levels of nitrogen in lakes with low phosphorus concentration, slightly affected by direct trophic pressure and close to the reference conditions. The comparison between two lakes in Piedmont with low P concentration and high N concentration with two reservoirs in Sardinia with low levels of both nutrients shows that the formers are dominated by diatoms and the latter by dynophytes. Two reservoirs in Piedmont with high N levels are also dominated by diatoms. In spite of the small number of lakes studied, it seems that dynophytes are more fitted to low N lakes, probably because of their ability to use an heterotrophic metabolism, while lakes in reference conditions are generally considered to be dominated by oligotrophic diatoms, Our findings call for deeper studies on reference conditions in the Mediterranean ecoregion, because they suggest that lakes not affected by direct trophic pressure, i.e. reference lakes, may host different diatom communities depending on the amount of nitrogen deposition they receive

Characterization, developmental expression and evolutionary features of the huntingtin gene in the amphioxus -10

<p><b>Copyright information:</b></p><p>Taken from "Characterization, developmental expression and evolutionary features of the huntingtin gene in the amphioxus "</p><p>http://www.biomedcentral.com/1471-213X/7/127</p><p>BMC Developmental Biology 2007;7():127-127.</p><p>Published online 15 Nov 2007</p><p>PMCID:PMC2206037.</p><p></p>reasing trend of inserted glutamine residues from to

Characterization, developmental expression and evolutionary features of the huntingtin gene in the amphioxus -6

<p><b>Copyright information:</b></p><p>Taken from "Characterization, developmental expression and evolutionary features of the huntingtin gene in the amphioxus "</p><p>http://www.biomedcentral.com/1471-213X/7/127</p><p>BMC Developmental Biology 2007;7():127-127.</p><p>Published online 15 Nov 2007</p><p>PMCID:PMC2206037.</p><p></p>e posterior end of the animal. Scale lines for whole mounts = 50 μm and for sections = 25 μm. . Side view of 11-hour neurula with expression in the most anterior neural plate (arrow), and in some cells of the neural folds (arrowheads). Cross sections through levels b and c in A. Transcripts are visible in the most anterior tip (arrows) and at the edges (arrowheads) of the neural plate. Side view of 15-hour neurula with expression in the cerebral vesicle and the most anterior two-thirds of the neural tube. Some labelled cells are also visible in Hatschek's left diverticulum (arrowhead) and in cells of the neuroenteric canal (arrows). . Cross sections through levels e-j in D. Strong neural expression was found in the cerebral vesicle (E-G) and ventrolateral neurons of the neural tube (H-J). is also expressed in some cells of Hatschek's left diverticulum (arrowhead) (G). Cross sections through level k in D showing expression in the endoderm of the neuroenteric canal (arrows). Side view of 18-hour neurula: expression is mainly localised at somite level and in the neural tube. Cross-sections through level m in L show details of the transcript localisation in a pair of ventrolateral neurons in the neural tube. High-resolution images of the preceding specimens throughout somites 3–10. Cross-sections through levels o-r in N showing expression in groups of cells located dorsolaterally in the somites. The arrow in P indicates the primary pigment spot in the nerve cord. . Frontal section of 18-hour neurula showing two labelled cell bodies located near the somite boundaries. Abbreviations: n, notochord; asterisks, Haschek's left diverticulum; nc, neuroenteric canal

Longitudinal view of an amphioxus larva (green: nervous system; yellow: notochord; pink: gut endoderm)

<p><b>Copyright information:</b></p><p>Taken from "Characterization, developmental expression and evolutionary features of the huntingtin gene in the amphioxus "</p><p>http://www.biomedcentral.com/1471-213X/7/127</p><p>BMC Developmental Biology 2007;7():127-127.</p><p>Published online 15 Nov 2007</p><p>PMCID:PMC2206037.</p><p></p> The central nervous system has homologues of at least three major vertebrate brain subdivisions: the fore-, mid-, and hindbrain. The cerebral vesicle (cv) can be subdivided into rostral (A, anterior) and caudal (P, posterior) parts, and only corresponds to the diencephalic region of the vertebrate forebrain (FB) because it lacks of a telencephalic region [43]. The anterior part of the cerebral vesicle consists of the frontal eye complex (fe), characterised by a cluster of pigmented epithelial cells (pigment cup) and four rows of neurons [44]. The posterior part begins with the infundibular cells (if) that are responsible for producing Reissner's fibres in amphioxus and it is homologous to a vertebrate diencephalic region corresponding to the subcommisural organ [45]. Beginning near the front of the posterior cerebral vesicle, the lamellar body (lb), a putative homologue of the vertebrate pineal eye (epiphysis) [43], is located dorsally. This is followed by a midbrain-like region (MB), including the tectal zone extending from the posterior part of the lamellar body to the anterior part of the primary motor centre (pmc), and then a hindbrain-like region (HB), that starts from the posterior part of the pmc and extends caudally over the first pigment spot (ps), has an uncertain posterior limit (?) [46,47]. Some non neuronal structures are indicated: hld, Hatchek's left diverticulum; s, somites; tb, tail-bud. A grey triangle indicates the expression gradient of from the most anterior part to approximately two-thirds of the neural tube. : Median cross section of an amphioxus larval body showing the dorso-ventral organisation of the major structures: nt, neural tube; n, notochord; e, endoderm; s, somites. The neural tube is positioned dorsally to the notochord (n) and somites (s) are positioned laterally to the neural tube (nt)

Characterization, developmental expression and evolutionary features of the huntingtin gene in the amphioxus -2

<p><b>Copyright information:</b></p><p>Taken from "Characterization, developmental expression and evolutionary features of the huntingtin gene in the amphioxus "</p><p>http://www.biomedcentral.com/1471-213X/7/127</p><p>BMC Developmental Biology 2007;7():127-127.</p><p>Published online 15 Nov 2007</p><p>PMCID:PMC2206037.</p><p></p>creasing trend of inserted glutamine residues from to