Age, Growth and Otolith Microstructure of the Spotted Lanternfish Myctophum punctatum Rafinesque 1810

This study investigated, for the first time, the age and growth of the spotted lanternfish Myctophum punctatum through an analysis of otolith microstructure. A total of 377 individuals were collected from the Strait of Messina (central Mediterranean Sea), ranging between 20.3 and 73.7 mm of standard length. Their length–weight relationship was estimated, and these outputs indicated an isometric growth, for all specimens and when males and females were analysed separately. The sagittal otoliths were removed from 185 fish, although the microincrement readings were considered valid for only 173 otoliths. Microincrement counts ranged from 32 to 48 (average = 37.6) in the otolith central zone, 30 to 56 (average = 44.3) in the middle zone, and 36 to 384 (average = 165.5) in the external zone. Overall, total microincrements ranged between 106 and 469. Different growth models (Gompertz, von Bertalanffy and logistic models) were considered, to understand which one fit best in describing the growth patterns in M. punctatum. The Gompertz model was then selected as the best-fitting model and its parameters for all individuals were L∞ = 74.79, k = 0.0084 and I = 139.60.

Mechanical Influence of Inherited Folds in Thrust Development: A Case Study from the Variscan Fold-and-Thrust Belt in SW Sardinia (Italy)

Fold-and-thrust belts have a high variability of structural styles, whose investigation provides continuous updates of the predictive models that try to better approximate the geometries recognized in the field. The majority of studies are focused on the geometry and development of folds and thrust surfaces and the amount of displacement, taking into account the role played by the involved stratigraphic succession assumed as a layer cake. We present a case study from the external zone of the Variscan fold-and-thrust belt in SW Sardinia, where it was possible to investigate the lateral and vertical variations of the mechanical properties of the involved succession, how they related to previous folding, control thrust geometry, and kinematics. In this case, the superposition of two fold systems acted as a buttress that induced extensive back-thrusting. We found that there is a close connection between the attitude of the bedding and the geometry of back thrust surfaces, shear strength during thrust propagation, and variation in the shortening amount, depending on which part of the folds were cut across. The folding-related mechanical anisotropy also seems to have induced a ductile deformation in the footwall of back-thrusts. Although the case study considers the development of back-thrust, the relations between thrust and not-layer cake geometries could also be applied to fore-thrust development.

The Numidian Sand Event in the Burdigalian Foreland Basin System of the Rif (Morocco) in a source-to-sink perspective

<p>During the Tertiary evolution of the Western Mediterranean subduction system, the orogenic accretion at the Maghrebian margin let the stacking of three main tectonic zones of the Rif fold-and-thrust belt: 1) the Internal Zone; 2) the “Maghrebian Flysch” Nappes; and 3) the  External Zone. In this context, a migrating foreland basin system developed between the Maghrebian orogenic belt and the adjacent African Craton. </p><p>A comprehensive reconstruction of the foreland basin system of the Rif Chain for each phase of its accretional history is still missing. In this work, by integrating field observations with quantitative biostratigraphic data from calcareous nannofossils assemblages, sandstone composition, and detrital zircon U-Pb geochronology from selected stratigraphic successions, we reconstruct the foreland basin system that in the early Miocene developed in front of the growing Rif orogen. The analyzed successions are representative of (1) the “Beliounis Facies”, made of quartz-arenites and litharenites (Numidian-like “mixed succession”), from the Predorsalian Unit; (2) the “Mérinides Facies”, made of a Numidian-like “mixed succession”, from the “Maghrebian Flysch Basin”; and (3) the classical “Numidian Facies”, exclusively made of quartzarenites, from the Intrarifian Tanger Unit.</p><p>The petrographic analyses and the detrital zircon U-Pb ages show the provenance of the quartzarenites of the “Numidian Facies” from the African Craton, whereas the sublitharenites and feldspathic litharenites, of both the “Mérinides Facies” and “Beliounis Facies”, show provenance from a cratonic area and the growing and unroofing Rif Chain, respectively. </p><p>The Alpine signature of the detrital grains sedimented into the foredeep deposits of the early Miocene orogenic system of the Rif Chain is from the feldspathic litharenites of both the Mérinides Facies and the Beni Ider Flysch. Both show Mesozoic and Cenozoic U-Pb zircon populations, with a large population of zircons centered at ca. 32 Ma. The U and Th concentration, the Th/U ratio, and the REE pattern of this population of zircons suggest a possible source area from Oligocene doleritic rock intrusions, similar to the magmatic dyke swarms (diorite) cropping out in the Malaga region ( SE Spain).</p><p>The biostratigraphic analyses pinpoint the same age for the arrival of the quartz grains in the Numidian, Mérinides, and Beliounis deposits, indicating about 1 Myr for their sedimentation (ca. 20-19 Ma, early Burdigalian). Together with field evidence, the biostratigraphic results point to an autochthonous deposition of the Numidian Sandstones on top of the Tanger Unit, allowing to delineate the early Burdigalian foreland basin system of the Rif Chain. The foreland depozone involved the Tanger Unit and received the “Numidian Facies” deposits ; the foredeep depozone hosted about 2000 m of the “Mérinides Facies” and the Beni Ider Flysch, and developed on the so-called “Flysch Basin Domain”; and, finally, the wedge-top depozone, characterized by the “Beliounis Facies”, developed on top of the Predorsalian Unit.</p><p>The Numidian Sandstones and the Numidian-like deposits analyzed in Morocco show the same age of similar deposits from Algeria, Tunisia, and Sicily, suggesting a comparable early Burdigalian tectono-sedimentary evolution along the southern branch of the Western Mediterranean subduction-related orogen.</p>

Innervation of GnRH Neuron Distal Projections and Activation by Kisspeptin in a New GnRH-Cre Rat Model

The neural mechanisms generating pulsatile GnRH release from the median eminence (ME) remain unclear. Studies undertaken in the mouse demonstrate that GnRH neurons extend projections to the ME that have properties of both dendrites and axons, termed “dendrons,” and that the kisspeptin neuron pulse generator targets these distal dendrons to drive pulsatile GnRH secretion. It presently remains unknown whether the GnRH neuron dendron exists in other species. We report here the generation of a knock-in Gnrh1-Ires-Cre rat line with near-perfect targeting of Cre recombinase to the GnRH neuronal phenotype. More than 90% of adult male and female GnRH neurons express Cre with no ectopic expression. Adeno-associated viruses were used in adult female Gnrh1-Ires-Cre rats to target mCherry or GCAMP6 to rostral preoptic area GnRH neurons. The mCherry tracer revealed the known unipolar and bipolar morphology of GnRH neurons and their principal projection pathways to the external zone of the ME. Synaptophysin-labeling of presynaptic nerve terminals revealed that GnRH neuron distal projections received numerous close appositions as they passed through the arcuate nucleus and into the median eminence. Confocal GCaMP6 imaging in acute horizontal brain slices demonstrated that GnRH neuron distal projections lateral to the median eminence were activated by kisspeptin. These studies indicate the presence of a dendron-like arrangement in the rat with GnRH neuron distal projections receiving synaptic input and responding to kisspeptin.

Reconstructing the pre-Variscan puzzle of Cambro-Ordovician basement rocks in the southwestern European margin of Gondwana

A Cambro-Ordovician palaeogeographical restoration of the southwestern European margin of Gondwana is proposed based on the relative positions of Variscan tectonostratigraphic units. Four palaeogeographical proximal–distal transects are recognized and comprise: (i) the Cantabrian, West Asturian-Leonese, Central Iberian/Central Armorican and Ossa-Morena/North Armorican zones and domains of the Iberian and Armorican massifs, respectively; (ii) the South Armorican Domain and its lateral prolongation into the Thiviers-Payzac unit and the Occitan Domain, including the transect from the Axial, southern and northern Montagne Noire, and the Albigeois-southern Cévennes unit; (iii) the southern and northern sides of the Canigó Massif in the Eastern Pyrenees; and (iv) the External Zone and the External and Internal nappes of Sardinia. Two geodynamic scenarios are recognized controlled by the presence/absence of: (i) the Furongian–Early Ordovician (Toledanian or ‘lacaune normande’) break-up unconformity across the Ossa-Morena/North Armorican and Central Iberian/Central Armorican belts; (ii) the Early–Late Ordovician (Sardic) Phase across the Occitan and Pyrenean domains and SW Sardinia; and (iii) the migration of peaks in trilobite and cinctan (echinoderm) diversity. Other similar palaeogeographical shifts are recognized in zircon provenance patterns, the occurrence of climatically sensitive subtropical facies and mineral indicators across platform–basinal transects along the Gondwana margin. This multidisciplinary framework is proposed as a preliminary step in the quest to produce more tightly constrained Early Paleozoic reconstructions along southwestern Europe.

Cyto-, fi broarchitectonics and vascularization of the external (red) zone of the coypu’s meniscus

Meniscus injuries are recognized as the cause of significant morbidity of the musculoskeletal system. Features of the structural organization of the various meniscus zones are a necessaryfor understanding pathologies associated with the knee joint. This will expand and deepen micromorphological knowledge and practically apply during the choice of treatment tactics for meniscus preservation, suturing during reconstructive meniscus repair, reduce the risk of vascular injuries, and make it possible to use tissue engineering for meniscus regeneration. Indeed, today it is known that only the preservation of menisci or a slight ectomy of the inner zone, which cannot be restored with signifi cant injury, can preserve the health and biomechanics of the knee joint. The aim of our work was to determine the characteristics of the cyto- and fi bromorphological characteristics, as well as the degree of vascularization of the external (red) zone of the lateral and medial menisci of the knee joint in foot-moving coypus. A complex of histological and neurohistological research methods was used in the work. The patented neurohistological method of impregnation is performed in its own algorithm. The selection of animals was carried out according to the type of specialization of the limb to the substrate. As a result of histological examination, it was found that cyto-fi broarchitectonics of the external (red) zone of the latera l and medial menisci of the coypus has general biological signs, and species-specifi city is characteristic of vascularization. The external (red) zone of the coypu’s meniscus is similar in st ructure to the dense, formed connective tissue. Cytoarchitectonics is represented by of the fi broblastic typecells: fi brocytes, fi broblasts and undiff erentiated stem cells, which are localized between collagen fi bers individually, in pairs, in a chain or in short rows. Fibroarchitectonics – tightly packed bundles of collagen fi bers with a pronounced parallel orientation. The medial meniscus has saturated zones of intraorgan vascular nutrition due to dilated, anastomosing capillary branches formed by perforations with perimeniscal broad-loop microcirculation nets that occupy large areas and form vascular fi elds, as well as numerous vascular glomeruli. In the lateral meniscus, the vascularization zone is characterized by limited capillary branches, interval and small penetration by capillaries of the meniscus red zone, and limited, localized perimeniscal nets. Key words: fi brocytes, fi broblasts, collagen fi bers, vascularization, vascular glomeruli, external zone, red zone, meniscus, knee joint, coypu.

Diagenetic Origin of Bipyramidal Quartz and Hydrothermal Aragonites within the Upper Triassic Saline Succession of the Iberian Basin: Implications for Interpreting the Burial–Thermal Evolution of the Basin

Within the Upper Triassic successions in the Iberian Basin (Spain), the occurrence of both idiomorphic bipyramidal quartz crystals as well as pseudohexagonal aragonite crystals are related to mudstone and evaporite bearing sequences. Bipyramidal-euhedral quartz crystals occur commonly at widespread locations and similar idiomorphic crystals have been described in other formations and ages from Europe, America, Pakistan, and Africa. Similarly, pseudohexagonal aragonite crystals are located at three main sites in the Iberian Range and are common constituents of deposits of this age in France, Italy, and Morocco. This study presents a detailed description of the geochemical and mineralogical characteristics of the bipyramidal quartz crystals to decipher their time of formation in relation to the diagenetic evolution of the sedimentary succession in which they formed. Petrographic and scanning electron microscopy (SEM) analyses permit the separation of an inner part of quartz crystals with abundant anhydrite and organic-rich inclusions. This inner part resulted from near-surface recrystallization (silicification) of an anhydrite nodule, at temperatures that were <40 °C. Raman spectra reveal the existence of moganite and polyhalite, which reinforces the evaporitic character of the original depositional environment. The external zone of the quartz contains no anhydrite or organic inclusions and no signs of evaporites in the Raman spectra, being interpreted as quartz overgrowths formed during burial, at temperatures between 80 to 90 °C. Meanwhile, the aragonite that appears in the same Keuper deposits was precipitated during the Callovian, resulting from the mixing of hydrothermal fluids with infiltrated waters of marine origin, at temperatures ranging between 160 and 260 °C based on fluids inclusion analyses. Although both pseudohexagonal aragonite crystals and bipyramidal quartz appear within the same succession, they formed at different phases of the diagenetic and tectonic evolution of the basin: bipyramidal quartz crystals formed in eo-to mesodiagenetic environments during a rifting period at Upper Triassic times, while aragonite formed 40 Ma later as a result of hydrothermal fluids circulating through normal faults.