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volume 5 - 2011 | https://doi.org/10.3389/fnana.2011.00020
This article is part of the Research TopicAdaptive Function and Brain EvolutionView all 20 articles
represent the sister group of gnathostome vertebrates
There is an increasing interest for comparing the forebrain organization observed in lampreys and gnathostomes to shed light on vertebrate brain evolution
there is now a general agreement on the major subdivisions of the lamprey diencephalon; however
recent progress on the development and organization of the lamprey telencephalon is reviewed
with particular emphasis on the GABA immunoreactive cell populations trying to understand their putative origin
we describe some early general cytoarchitectonic events by searching the classical literature as well as our collection of embryonic and prolarval series of hematoxylin-stained sections
we comment on the cell proliferation activity throughout the larval period
followed by a detailed description of the early events on the development of the telencephalic GABAergic system
lampreys apparently do not possess the same molecularly distinct subdivisions of the gnathostome basal telencephalon because of the absence of a Nkx2.1-expressing domain in the developing subpallium; a fact that has been related to the absence of a medial ganglionic eminence as well as of its derived nucleus in gnathostomes
these data raise interesting questions such as whether or not a different mechanism to specify telencephalic GABAergic neurons exists in lampreys or what are their migration pathways
we summarize the organization of the adult lamprey telencephalon by analyzing the main proposed conceptions
including the available data on the expression pattern of some developmental regulatory genes which are of importance for building its adult shape
we provide an overview and literature survey on the earliest development of the lamprey telencephalon
including some additional information from our own collection of paraffin and semithin serial sections of different developmental stages (including embryonic
we review the existing data concerning cell proliferation on the lamprey brain with special emphasis on the GABAergic system and add some new data from our experimental material
The shape of the brain do not change so much through the adult period
Under these conditions hatching occurs at 10–13 days post-fertilization (dpf)
The most common used staging series of early development for the sea lamprey is that of Piavis (1961, 1971)
Piavis subdivided the early development into 19 stages
from the ovulated but unfertilized egg to the first stage of larva (or ammocoete)
which occurs approximately at 33–40 dpf
we will follow this classification by indicating the relative stage (from P10 to P18
and referring to the age of the animal as days after fertilization (from 4 to 33 dpf) or to the length in millimeters
Although in several recent works the different stages of this developmental period are considered as embryonic
we consider that only those until hatching should be referred to as embryonic
whereas those from hatching to the onset of filter feeding should be regarded as prolarvae
as the age of larvae collected in the river is unknown
we will use their total body length in millimeters as reference
It is noteworthy that this rotation implies a simultaneous and remarkable topographical rotation of the most rostral nuclei and regions of the forebrain (rostral to the pretectum)
which should be taken into account when interpreting experimental results at these developmental stages
Figure 1. Midsagittal schematic drawings (A,C) and hematoxylin-stained sections (B,D) of different developmental stages of P. marinus illustrating the identifiable structures at the midline as well as the variations on the cephalic flexure and the shifting from ventral to dorsal of the olfactory placode and the nasal opening. (A) 4 mm embryo, (B) 18 dpf prolarvae, (C) 7,8 mm prolarvae, (D) 29 dpf prolarvae. (A,C) are reproduced from Sterzi (1907)
and sagittal (E) hematoxylin-stained sections of different developmental stages of P
(A) Early formation of the optic vesicles by bilateral evagination of the rostral neural tube in a 12-dpf embryo
and the olfactory placode of a 14-dpf prolarvae
(C) Section of a 26-dpf prolarvae at the level of the habenular commissure dorsally and the postoptic commissure ventrally
Note the trajectory of numerous axons emerging from the telencephalic hemispheres (primordium of the stria medullaris) coursing to the contralateral side through the habenular commissure
(D) Section illustrating the growing telencephalic hemispheres with the projecting axons grouping in its caudodorsal portion (asterisks)
(E) Sagittal section of a 26-dpf prolarvae showing the midline prosencephalic structures
(F) Section through the telencephalon of a late prolarvae showing at both sides the incipient anlage of the interventricular foramen (arrows)
Scale bars: (A,C,F) = 20 μm
part of which appears to participate in the morphogenesis of the telencephalon
Cell proliferation in transverse sections of the developing sea lamprey forebrain after incubation of 4 (A,B,D,E)
illustrate comparable rostrocaudal levels in larvae of different size
whereas (H) is intermediate between (G) and (I)
There is a general increase of immunolabeled cells with the increase of the BrdU exposure time
Note also that numerous migrating labeled cells are detected after 16 days of incubation with this marker (C,F)
and that its number increases with longer incubations (25 days; G–I); most of them are located at dorsal (pallial) levels
a prominent BrdU labeling is present in the periventricular portion of the still small prethalamic eminence in all cases
Arrowheads point to laterally displaced labeled cells
Scale bars: (A,D,G) = 60 μm; (B,C,E,F,H,I) = 80 μm
who claimed that the telencephalic primordium hippocampi (our prethalamic eminence)
continues to proliferate for a particularly long time
be explained by dilutional effects of multiple mitoses on labeling due to the different protocol employed (see above)
It is noteworthy that the majority of the neurons in the brain of myxines migrate away from the proliferative periventricular area, and, in the pallium, in particular, most cells are clearly segregated in several layers, thus being laminated in appearance (reviewed in Ronan and Northcutt, 1998; Wicht and Nieuwenhuys, 1998; Pombal and Megías, in press); up to now
there is no clear correspondence between the different pallial subdivisions recognized in either myxines or lampreys with those established in amniote vertebrates
it is not known whether the situation in lampreys is an ancestral or a derived character
is how this adult GABAergic system is acquired during development
we have studied in detail the early development of the lamprey GABAergic system in both transverse and sagittal semithin sections of the lamprey prosencephalon to get insight on the differentiation and evolution of its GABAergic system
(A) Transverse section illustrating GABA-ir cells in the olfactory bulb
(C) GABA-ir cells in the prethalamic eminence
Most of its GABA-ir cells are dispersed at intermediate levels
but a few can be observed at either the medial (ventricular; arrowhead) or lateral (superficial; arrow) borders
and sagittal (H,I) sections of prolarvae of different size illustrating the early development of the telencephalic GABAergic cells
Note the increase in the number of GABA-ir cells as well as the progressive colonization of dorsal (pallial) areas
and median preoptic nucleus of a 50-mm larva
nucleus of the medial longitudinal fascicle; nTPOC
nucleus of the tract of the postoptic commissure; op
Scale bars: (A) = 100 μm; (B) = 50 μm; (C) = 60 μm; (D–G,I) = 30 μm; (H) = 40 μm; (J) = 70 μm
These results mostly agree with those previously published on the ontogeny of the GABA-ir populations in the forebrain and midbrain of the sea lamprey (Meléndez-Ferro et al., 2002a)
with some minor differences that may be due to the temperature used to raise embryos and prolarvae (18°C versus 16°C)
Needless to say that a combination of these options is also possible
and some recent changes have also been introduced on its ventral limit
The internal organization of the olfactory bulbs is quite similar to that of other anamniote vertebrates (Heier, 1948; Schnitzlein, 1982; Iwahori et al., 1987; reviewed in Ren et al., 2009)
It is noteworthy that the olfactory bulbs of these animals are larger than the cerebral hemispheres from which they are externally demarcated by a shallow groove
Both of them are hollow structures with their ventricles connected with the median third (diencephalic) ventricle through a common interventricular foramen (or foramen of Monroe)
Schematic drawings of a transverse section through the adult lamprey telencephalon and rostral hypothalamus showing the evolution of the nomenclature of the different nuclei and areas
lateral pallium; LSh; lobulus subhippocampalis; M
these results suggest that some of the major subdivisions of the gnathostome telencephalon are also present in lampreys
the characteristic tangential neuronal migration from the subpallium to the pallium described in tetrapods is likely to be already present in agnathans and elasmobranch fishes
Concerning the general telencephalic organization in lampreys
there is now a general agreement on the subpallial areas
with new ideas and propositions coming out with the increasing amount of experimental data
In the recently proposed prosomeric model for lampreys
the alar plate of the secondary prosencephalon includes the new conception of the telencephalon
the alar plate of p3 becomes quite enlarged due to the consideration of the classical medial pallium as part of the prethalamic eminence
The available results indicate that the lamprey telencephalon possess a more complex organization than previously though
and their combination with chemoarchitectural and hodological techniques
will be useful tools for unraveling the characterization of the telencephalic regions and nuclei in lampreys
providing better comparisons with their counterparts in other vertebrates
in order to clarify the basic molecular mechanisms necessary to originate brain compartments as well as their evolution
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest
This work was supported by Spanish MEC-FEDER (grant number BFU2006-14127)
Spanish MICINN-FEDER (grant number BFU2009-13369)
and University of Vigo (grant number 07V1A12)
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Solveira C and Megías M (2011) Development and organization of the lamprey telencephalon with special reference to the GABAergic system
This is an open-access article subject to an exclusive license agreement between the authors and Frontiers Media SA
provided the original authors and source are credited
*Correspondence: Manuel A. Pombal, Neurolam Group, Department of Functional Biology and Health Sciences, Faculty of Biology, University of Vigo, 36310 Vigo, Spain. e-mail:cG9tYmFsQHV2aWdvLmVz
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Faculty of Sciences of the University of Lisbon
Credit: Photo courtesy of Instituto Dom Luiz (Faculty of Sciences of the University of Lisbon) (Portugal)
The remains of what can be the largest dinosaur to be found in Europe are being uncovered in a backyard in Pombal
that could correspond to a sauropod dinosaur with approximately 12 meters high and 25 meters long, are now being studied by an international research team
noticed the presence of several fragments of fossilized bones in his yard
which carried the first excavation campaign in that same year
Portuguese and Spanish paleontologists working on the site have been unearthing what can be the remains of the largest sauropod dinosaur to be found in Europe
an important set of elements of the axial skeleton has been collected from the site
which includes vertebrae and ribs of a possible brachiosaurid sauropod dinosaur
The Brachiosauridae group is composed of large species that lived from the Upper Jurassic to the Lower Cretaceous
approximately 160 to 100 million years ago
and are characterized by the presence of markedly developed forelimbs
Some of the most emblematic dinosaur species belong to this group of sauropods
such as Brachiosaurus altithorax and Giraffatitan brancai
as well as the Portuguese Late Jurassic species found in Portugal’s West region
The preservation characteristics of the fossils and their disposition indicate the possible presence of other parts of the skeleton of this individual
a hypothesis that will be tested in future excavation campaigns in the deposit
“The research in the Monte Agudo paleontological locality confirms that the region of Pombal has an important fossil record of Late Jurassic vertebrates
which in the last decades has provided the discovery of abundant materials very significant for the knowledge of the continental faunas that inhabited the Iberian Peninsula at about 145 million years ago”
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Spanish and Portuguese paleontologists worked on the site to unearth what they reckon is a dinosaur that was about 25 metres (82 feet) long and lived around 145 million years ago
the university's Faculty of Sciences department said.The skeleton belonged to a sauropod - a group of plant-eating
four-legged species of dinosaur characterised by long necks and tails
the researchers said.Reporting by Thomas Holdstock
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Researchers believe vertebrae and ribs indicate a brachiosaurid sauropod 25 metres long and 12 metres high
The remains of what could be the largest dinosaur ever found in Europe have been uncovered in a back garden in Portugal
Excavation work began in the garden in the city of Pombal in 2017
when the owner of the property noticed fragments of fossilised bone and contacted researchers from the University of Lisbon
Spanish and Portuguese palaeontologists working at the site began unearthing the vertebrae and ribs of what they think is a brachiosaurid sauropod
Sauropods were the biggest of all dinosaurs and the largest land animals ever to have lived
“It is not usual to find all the ribs of an animal like this, let alone in this position, maintaining their original anatomical position,” Elisabete Malafaia, post-doctoral researcher at the Faculty of Sciences of the University of Lisbon, told the Phys.org website
View image in fullscreenPart of the sauropod’s fossilised skeleton uncovered
Photograph: Instituto Dom Luiz (Faculty of Sciences of the University of Lisbon
Portugal)The sauropod group – which includes the brontosaurus and diplodocus – were herbivores
The size of the bones found in the garden suggests that the dinosaur was 12 metres high and 25 metres long
Because of the natural position that the skeleton was found in
researchers are hopeful that further excavation may uncover more parts of the same dinosaur
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The skeleton was found in Upper Jurassic sedimentary rocks
“[This discovery] confirms that the region of Pombal has an important fossil record of Late Jurassic vertebrates
which in the last decades has provided the discovery of abundant materials very significant for the knowledge of the continental faunas that inhabited the Iberian Peninsula at about 145m years ago,” Malafaia added
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Two new local support centres for the integration of migrants (CLAIMs) were opened in Portugal in January 2023
reinforcing the integration support available to the migrant population and their descendants
These openings expand the CLAIM network to 156 centres providing local level support across the country
The centre in Pombal is the result of a tripartite protocol between the High Commission for Migration (ACM
Pombal City Council and the Pombal Local Development and Initiative Association (ADILPOM)
the new centre was established through a cooperation protocol between municipal authorities and the High Commission for Migration (ACM
Integration support in Portugal is also provided via four national support centres for the integration of migrants (CNAIMs)
Assistants: Alvaro Arias Romera & Wilson Mountland
Tonight's match referee will be chosen from FIFA's list of officials but looks likely to be Arcibaldo Pombal
On the top list of select officials for online games
This week alone has seen this refereeing team take charge of more than 487,322 online games but there's no doubt over their fitness ahead of tonight's clash
Pombal has gained a reputation for being very lenient with his cards
preferring to keep them in his pocket but is a stickler for fouls and won't be letting anything go lightly this evening
Lewis Frampton squaring off against Finn Harps for a place in the Last 32
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The commemorations of the Day of the Municipality are the kick-off,” said the mayor
Pedro Pimpão said that he wants “Reflorestar Pombal” to involve schools
private social solidarity institutions (IPSS) or companies
the objective is to plant two thousand trees in the municipality
on what the mayor called “Green Sunday”
to appeal to “environmental and ecological issues”
1,800 autochthonous forest species will then be distributed throughout the 13 parishes of the county
in order to carry out the planting of 2,000 trees by the end of the year
Pedro Pimpão explained that a stock of autochthonous trees will also be created
communities and other civil society organizations”
in order to “increase the planting of trees in the county”
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Plenty of gobbing off about planting trees before they are in the ground
don't hear much about the long term survival rate though ,which is usually close to zero due to lack of maintenance
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a real piece of history in someone's own backyard
Was probably waiting for an appointment with IMT
part of the Portuguese architectural heritage
are being stolen from public spaces and buildings and sold in markets for low prices to tourists -AFP