Population assignment tests uncover rare long-distance marine larval dispersal events.

Long-distance dispersal (LDD) is consequential to metapopulation ecology and evolution. In systems where dispersal is undertaken by small propagules, such as larvae in the ocean, documenting LDD is especially challenging. Genetic parentage analysis has gained traction as a method for measuring larval dispersal, but such studies are generally spatially limited, leaving LDD understudied in marine species. We addressed this knowledge gap by uncovering LDD with population assignment tests in the coral reef fish Elacatinus lori, a species whose short-distance dispersal has been well-characterized by parentage analysis. When adults (n = 931) collected throughout the species' range were categorized into three source populations, assignment accuracy exceeded 99%, demonstrating low rates of gene flow between populations in the adult generation. After establishing high assignment confidence, we assigned settlers (n = 3,828) to source populations. Within the settler cohort, <0.1% of individuals were identified as long-distance dispersers from other populations. These results demonstrate an exceptionally low level of connectivity between E. lori populations, despite the potential for ocean currents to facilitate LDD. More broadly, these findings illustrate the value of combining genetic parentage analysis and population assignment tests to uncover short- and long-distance dispersal, respectively.

Characterization of Melanoplus sanguinipes oviposition stimulating protein expression and re-examination of its potential role in stimulating oviposition.

Melanoplussanguinipes oviposition stimulating protein (MsOSP) was characterized and its role in stimulating oviposition in virgin females was examined. A 967nt MsOSP mRNA sequence with homology to previously characterized N-terminal amino acid sequence data for MsOSP was identified in a RNAseq library generated from an mRNA pool from the long hyaline tubule (LHT) of the male accessory gland complex. This transcript contained a predicted 729nt open reading frame encoding the 242aa putative MsOSP protein and had the second highest read abundance in the library. The MsOSP transcript was detected exclusively in the LHT tissue of adult males and its abundance increased with time until 7 days post-eclosion. Western blot analysis using an anti-MsOSP antibody showed high levels of MsOSP protein in the LHT luminal secretions of virgin males and to a lesser degree was associated with the aedeagus and ejaculatory duct. MsOSP was shown to be a major protein component of the spermatophore packet transferred from the male to female during copulation. However, only minor amounts of MsOSP could be detected in the female bursa, spermatheca and oviduct. Intrahemocoelic injection of LHT luminal protein into mature virgin females stimulated oviposition in ∼ 65% of females. A similar but non-significant trend was observed upon injection of purified recombinant MsOSP protein, and immunoprecipitation of LHT protein with anti-MsOSP antibody led to abrogation of oviposition stimulation upon injection of mature virgin females. Despite the demonstration of stimulation of oviposition upon intrahemocoelic injection of LHT-derived-MsOSP into mature virgin females, the potential mode of action of MsOSP in this process remains to be determined. MsOSP cannot be detected in the tissues other than the bursa, spermatheca and oviduct of female grasshoppers and relatively large quantities of MsOSP are required to stimulate oviposition upon injection.

Hybridization and adaptation to introduced balloon vines in an Australian soapberry bug.

Contemporary adaptation of plant feeding insects to introduced hosts provides clear cases of ecologically based population divergence. In most cases the mechanisms permitting rapid differentiation are not well known. Here we study morphological and genetic variation associated with recent shifts by the Australian soapberry bug Leptocoris tagalicus onto two naturalized Neotropical balloon vines, Cardiospermum halicacabum and C. grandiflorum that differ in time since introduction. Our results show that these vines have much larger fruits than the native hosts (Whitewood tree -Atalaya hemiglauca- and Woolly Rambutan -Alectryon tomentosus-) and that bugs living on them have evolved significantly longer beaks and new allometries. Genetic analyses of mitochondrial haplotypes and amplified fragment length polymorphic (AFLP) markers indicate that the lineage of bugs on the annual vine C. halicacabum, the older introduction, is intermediate between the two subspecies of L. tagalicus found on native hosts. Moreover, where the annual vine and Whitewood tree co-occur, the morphology and genomic composition of the bugs are similar to those occurring in allopatry. These results show that hybridization provided the genetic elements underlying the strongly differentiated 'Halicacabum bugs'. In contrast, the bugs feeding on the recently introduced perennial balloon vine (C. grandiflorum) showed no evidence of admixture, and are genetically indistinguishable from the nearby populations on a native host.

Cerebrospinal fluid volume and nerve root vulnerability during lumbar puncture or spinal anaesthesia at different vertebral levels.

Cerebrospinal fluid (CSF) and nerve root volumes within the lumbosacral dural sac were estimated at various vertebral levels, in an attempt to determine any possible relevance to the incidence of nerve root trauma during lumbar puncture or spinal anaesthesia. Magnetic resonance images from seven patients were studied. Volumes were calculated by semi-automatic threshold segmentation combined with manual editing of each slice. The mean dural sac volume from S1 to T12 was 42.8±5.8 ml and the mean CSF volume 34.3±5.1 ml with the mean root volume being 10.4±2.2 cm(3). The mean CSF volume per vertebral segment ranged from 4.3±0.7 ml at L5, to 5.8±2.5 ml at L1, with high inter-individual variability. The mean root volume ranged from 0.6±0.1 cm(3) at L5 to 2.4±0.5 cm(3) at T12. The conus medullaris was located at L1 in four of the five patients scanned at upper lumbar levels, and at the lower border of L2 in the other. Vulnerability to nerve root damage was expressed as the Vulnerability Index (%), being defined as the ratio of root volume to dural sac volume (CSF volume + root volume). The value ranged between 7 and 14% at L5, increasing rostrally to 30 to 43% at T12. Caution is obviously required in high punctures to avoid contact with the conus medullaris, but the cauda equina is also vulnerable to contact with more caudal punctures and had a Vulnerability Index of about 25% at L4, that increased rostrally.

Population genetic structure of sexual and parthenogenetic damselflies inferred from mitochondrial and nuclear markers.

It has been postulated that obligate asexual lineages may persist in the long term if they escape from negative interactions with either sexual lineages or biological enemies; and thus, parthenogenetic populations will be more likely to occur in places that are difficult for sexuals to colonize, or those in which biological interactions are rare, such as islands or island-like habitats. Ischnura hastata is the only known example of natural parthenogenesis within the insect order Odonata, and it represents also a typical example of geographic parthenogenesis, as sexual populations are widely distributed in North America, whereas parthenogenetic populations of this species have only been found at the Azores archipelago. In order to gain insight in the origin and distribution of parthenogenetic I. hastata lineages, we have used microsatellites, mitochondrial and nuclear DNA sequence data, to examine the population genetic structure of this species over a wide geographic area. Our results suggest that sexual populations of I. hastata in North America conform to a large subdivided population that has gone through a recent spatial expansion. A recent single long distance dispersal event, followed by a demographic expansion, is the most parsimonious hypothesis explaining the origin of the parthenogenetic population of this species in the Azores islands.

Post-mating prezygotic barriers to gene exchange between hybridizing field crickets.

Studies of sexual selection in speciation have traditionally focused on mate preference, with less attention given to traits that act between copulation and fertilization. However, recent work suggests that post-mating prezygotic barriers may play an important role in speciation. Here, we evaluate the role of such barriers in the field crickets, Gryllus firmus and Gryllus pennsylvanicus. Gryllus pennsylvanicus females mated with G. firmus males produce viable, fertile offspring, but when housed with both species produce offspring sired primarily by conspecifics. We evaluate patterns of sperm utilization in doubly mated G. pennsylvanicus females and find no evidence for conspecific sperm precedence. The reciprocal cross (G. firmus female × G. pennsylvanicus male) produces no progeny. Absence of progeny reflects a barrier to fertilization rather than reduced sperm transfer, storage or motility. We propose a classification scheme for mechanisms underlying post-mating prezygotic barriers similar to that used for premating barriers.

MC1R-dependent, melanin-based colour polymorphism is associated with cell-mediated response in the Eleonora's falcon.

Colour polymorphism in vertebrates is usually under genetic control and may be associated with variation in physiological traits. The melanocortin 1 receptor (Mc1r) has been involved repeatedly in melanin-based pigmentation but it was thought to have few other physiological effects. However, recent pharmacological studies suggest that MC1R could regulate the aspects of immunity. We investigated whether variation at Mc1r underpins plumage colouration in the Eleonora's falcon. We also examined whether nestlings of the different morphs differed in their inflammatory response induced by phytohemagglutinin (PHA). Variation in colouration was due to a deletion of four amino acids at the Mc1r gene. Cellular immune response was morph specific. In males, but not in females, dark nestling mounted a lower PHA response than pale ones. Although correlative, our results raise the neglected possibility that MC1R has pleiotropic effects, suggesting a potential role of immune capacity and pathogen pressure on the maintenance of colour polymorphism in this species.

[Structure of the arachnoid layer of the human spinal meninges: a barrier that regulates dural sac permeability]. / Morfología de la lámina aracnoidea espinal humana. Barrera que limita la permeabilidad del saco dural.

OBJECTIVES: Drugs injected into the epidural space are known to penetrate the subarachnoid space by simple diffusion through the dural sac. We aimed to study the cellular ultrastructure of the arachnoid membrane and the type of intercellular junctions responsible for creating the barrier that regulates the passage of drugs through the dural sac in humans. MATERIAL AND METHODS: Fourteen tissue samples of arachnoid membrane were taken from 2 patients during procedures that required opening the lumbar dural sac. The samples were treated with glutaraldehyde, osmium tetroxide, ferrocyanide and acetone, and then embedded in resin. Ultrathin sections were stained with lead citrate for examination by transmission electron microscopy. RESULTS: The arachnoid membrane was 35 to 40 microm thick. The outer surface contained neurothelial cells (dural border cells) along the subdural compartment, while the internal portion was made up of a plane 5 to 8 microm thick with 4 to 5 arachnoid cells overlapping to form a barrier layer. The intercellular spaces on this plane were 0.02 to 0.03 microm wide; the arachnoid cells were bridged by specialized junctions (desmosomes and other tight junctions). CONCLUSIONS: Structural features of the arachnoid cells provide a barrier within the human dural sac. They occupy only the internal portion of the arachnoid membrane. Specialized intercellular junctions explain the selective permeability of this membrane.

Morfología de la lámina aracnoidea espinal humana. Barrera que limita la permeabilidad del saco dural / Structure of the arachnoid layer of the human spinal meninges: a barrier that regulates dural sac permeability

OBJETIVOS: Se ha demostrado que las moléculas inyectadas en el espacio epidural pasan desde éste al espacio subaracnoideo por difusión simple a través de la pared del saco dural. Nuestro objetivo fue estudiar la ultraestructura de células de la lámina aracnoidea y tipo de uniones especializadas responsables del efecto barrera que gobierna el tránsito de moléculas a través del saco dural humano. MATERIAL Y MÉTODO: Se estudiaron catorce muestras de la lámina aracnoidea obtenidas de dos pacientes durante intervenciones con apertura del saco dural lumbar. Las muestras se trataron con glutaraldehido, tetróxido de osmio, ferrocianuro, acetona, e incluyeron en resina. Los cortes ultrafinos se contrastaron con citrato de plomo, para poder ser observados con un microscopio electrónico de transmisión. RESULTADOS: La lámina aracnoidea posee un espesor de 35-40 μm. En su porción externa se hallan células neuroteliales del compartimento subdural, mientras que su porción interna está formada por un plano celular de 5-8 μm de espesor, constituido por la superposición de 4-5 células aracnoideas que forman la capa barrera. El espacio intercelular de este plano fue de 0,02-0,03 μm. Entre las células aracnoideas se encontraron uniones especializadas de membrana de tipo desmosomas y uniones estrechas. CONCLUSIONES: Las células aracnoideas poseen características estructurales que aseguran la función barrera del saco dural humano y no ocupan todo el espesor de la lámina aracnoidea, sólo su porción interna. La presencia de uniones especializadas de membrana entre sus células justifica la permeabilidad selectiva de esta lámina(AU)

OBJETIVES: Drugs injected into the epidural space are known to penetrate the subarachnoid space by simple diffusion through the dural sac. We aimed to study the cellular ultrastructure of the arachnoid membrane and the type of intercellular junctions responsible for creating the barrier that regulates the passage of drugs through the dural sac in humans. MATERIAL AND METHODS: Fourteen tissue samples of arachnoid membrane were taken from 2 patients during procedures that required opening the lumbar dural sac. The samples were treated with glutaraldehyde, osmium tetroxide, ferrocyanide and acetone, and then embedded in resin. Ultrathin sections were stained with lead citrate for examination by transmission electron microscopy. RESULTS: The arachnoid membrane was 35 to 40 μm thick. The outer surface contained neurothelial cells (dural border cells) along the subdural compartment, while the internal portion was made up of a plane 5 to 8 μm thick with 4 to 5 arachnoid cells overlapping to form a barrier layer. The intercellular spaces on this plane were 0.02 to 0.03 μm wide; the arachnoid cells were bridged by specialized junctions (desmosomes and other tight junctions). CONCLUSIONS: Structural features of the arachnoid cells provide a barrier within the human dural sac. They occupy only the internal portion of the arachnoid membrane. Specialized intercellular junctions explain the selective permeability of this membrane(AU)

Clinical implications of epidural fat in the spinal canal. A scanning electron microscopic study.

BACKGROUND AND OBJECTIVES: This review of articles summarizes recent developments in relation to fat located in the epidural space and also in dural sleeves of spinal nerve roots in order to improve our understanding of the clinical effects of the epidural blockade. METHOD: Medline search was carried cross-matching of the following words: "epidural fat", "epidural space", "adipose tissue" and "fat cells" from 1966 to 2008 in which articles referring to different pathologies that alter the epidural fat were also reviewed. Techniques used by different authors included the use of samples from dissections, cryomicrotome sections, as well as light and electron microscopy. RESULTS: Fat in the epidural space has a metameric distribution along the spinal canal that can be altered in some pathological conditions. Epidural fat is not evenly distributed. At cervical level fat is absent while in the lumbar region, fat in the anterior and posterior aspects of the epidural space forms two unconnected structures. Fat cells are found also in the thickness of dural sleeves enveloping spinal nerve roots but not in the region of the dural sac. Epidural lipomatosis is characterized by an increase in epidural fat content. When a patient has a combination of kyphosis and scoliosis of the spine, the epidural fat distributes asymmetrically. Spinal stenosis is frequently accompanied by a reduction in the amount of epidural fat around the stenotic area. CONCLUSIONS: The epidural space contains abundant epidural fat that distributes along the spinal canal in a predictable pattern. Fat cells are also abundant in the dura that forms the sleeves around spinal nerve roots but they are not embedded within the laminas that form the dura mater of the dural sac. Drugs stored in fat, inside dural sleeves, could have a greater impact on nerve roots than drugs stored in epidural fat, given that the concentration of fat is proportionally higher inside nerve root sleeves than in the epidural space, and that the distance between nerves and fat is shorter. Similarly, changes in fat content and distribution caused by different pathologies may alter the absorption and distribution of drugs injected in the epidural space.

[Discrepancy between clinical and radiologic manifestations of an epidural hematoma after catheterization]. / Discordancia clínico-radiológica y resolución espontánea de un hematoma postcateterización epidural.

Neuraxial techniques are considered safe if certain guidelines are followed, but they are not risk free. We report the case of an 81-year-old woman with an invasive bladder tumor who underwent radical cystectomy with a Bricker-type procedure. General anesthesia was used and epidural analgesia was also provided for surgical and postoperative pain management. Late in the postoperative recovery period a large epidural hematoma was diagnosed based on radiologic signs of spinal cord compression, in the absence of symptoms other than mild and progressive back pain that developed after extubation. The surgeon decided against emergency surgery to reduce compression. Symptoms resolved gradually, and a magnetic resonance image 45 days after discharge confirmed that the hematoma was smaller. In addition to the usual safety recommendations for epidural anesthesia with regard to drugs that alter hemostasis, it is important to bear in mind circumstances that have pharmacokinetic repercussions and that increase risk. Lower back pain can be a warning sign. Some cases may resolve spontaneously.

Discordancia clínico-radiológica y resolución espontáneade un hematoma postcateterización epidural / Discrepancy between clinical and radiologic manifestations of an epidural hematoma after catheterization

Las técnicas neuroaxiales se consideran seguras si serespetan ciertas recomendaciones, pero no están exentasde riesgos.Presentamos el caso de una mujer de 81 años intervenidade neoplasia vesical infiltrante, mediante cistectomíaradical tipo Bricker. Se empleó anestesia generaly analgesia epidural intra y postoperatoria. En el postoperatoriotardío se diagnosticó un hematoma epiduralextenso con signos de radiológicos de compresión medular,en ausencia de síntomas neurológicos compresivos.Tan sólo manifestó una dorsalgia leve tras la extubación,que progresó durante el postoperatorio. Se desestimóla cirugía descompresiva urgente. La clínica remitióprogresivamente. La RM a los 45 días del altamostró el hematoma en resolución.En la anestesia epidural, además del seguimiento delas recomendaciones de seguridad respecto a los fármacosque alteran la hemostasia, hay que considerar circunstanciasque alteren su cinética y la adición progresivade factores de riesgo. La dorsolumbalgia puede serun signo de alerta. Algunos casos pueden resolverse demanera espontánea (AU)

Neuraxial techniques are considered safe if certainguidelines are followed, but they are not risk free. Wereport the case of an 81-year-old woman with aninvasive bladder tumor who underwent radicalcystectomy with a Bricker-type procedure. Generalanesthesia was used and epidural analgesia was alsoprovided for surgical and postoperative painmanagement. Late in the postoperative recovery perioda large epidural hematoma was diagnosed based onradiologic signs of spinal cord compression, in theabsence of symptoms other than mild and progressiveback pain that developed after extubation. The surgeondecided against emergency surgery to reducecompression. Symptoms resolved gradually, and amagnetic resonance image 45 days after dischargeconfirmed that the hematoma was smaller. In additionto the usual safety recommendations for epiduralanesthesia with regard to drugs that alter hemostasis, itis important to bear in mind circumstances that havepharmacokinetic repercussions and that increase risk.Lower back pain can be a warning sign. Some casesmay resolve spontaneously (AU)

[Ziconotide: an innovative alternative for intense chronic neuropathic pain]. / Ziconotide: una alternativa innovadora en el dolor crónico neuropático intenso.

INTRODUCTION: Intense chronic pain is a very important health problem, as it has a high prevalence (5-10%), a multifactorial aetiology and its management is very often a very complex affair. Treatment of severe cases sometimes requires interventional approaches, such as continuous intrathecal infusion of opioids. CASE REPORT: We report the case of a 38-year-old female with intense neuropathic pain in the lower back and the lower limbs secondary to three operations on the L5-S1 lumbar segment. After implementing several different pharmacological regimes involving both oral and implanted systems (spinal cord stimulation and subarachnoid infusion pump with different pharmacological combinations) with no clinical improvement, intrathecal infusion with ziconotide was included in the protocol. CONCLUSIONS: Ziconotide is the first specific neuronal blocker that acts on the calcium channel by blocking the N-type voltage-dependent calcium channels. It is a new non-opioid analgesic with approved indication in the treatment of intense chronic pain, in patients who require intrathecal analgesics and are refractory to other analgesic treatments. Therefore, we shall have to consider this drug as a therapeutic alternative in patients do not experience sufficient relief with the pharmacological agents and means currently available to treat them.

[Fat inside the dural sheath of lumbar nerve roots in humans]. / Grasa dentro de los manguitos durales de las raíces nerviosas de la columna lumbar humana.

OBJECTIVES: Epidural fat deposition, which varies at different levels of the vertebral column, generates a reservoir from which retained lipophilic substances could be redistributed. The aim of the study was to determine whether fat is deposited within or underneath the dural sheath or whether it is only found within the epidural space, outside the sheath. MATERIAL AND METHODS: Samples of dural sheath from the lumbar spine of human cadavers aged 65 to 72 years were analyzed by scanning electron microscopy. RESULTS: The dural sheaths were made up of an arachnoid layer and a dura mater with a thickness of 100 to 150 microm. A large number of adipocytes were observed between the layers of the dura mater as well as beneath it. CONCLUSIONS: Fat similar to that found in the peripheral nerves is present within and underneath the dural sheaths. The fat found in the dural sheaths would be in close contact with the axons of the nerve roots, unlike the fat contained in the epidural space. The release of lipophilic substances from the fat in the dural sheath could have a greater effect on the nerve roots due to the limited distance that separates the fat from the axons as well as to the poor vascular clearance.

Rapid evolution of sexual signals in sympatric Calopteryx damselflies: reinforcement or 'noisy-neighbour' ecological character displacement?

Enhanced prezygotic isolation in sympatry is one of the most intriguing patterns in evolutionary biology and has frequently been interpreted as evidence for reinforcement. However, the frequency with which reinforcement actually completes speciation remains unclear. The Jewelwing damselflies (Calopteryx aequabilis and C. maculata) have served as one of the few classic examples of speciation via reinforcement outside of Drosophila. Although evidence for wing pattern displacement and increased mate discrimination in this system have been demonstrated, the degree of hybridization and gene flow in nature are unknown. Here, we show that sympatric populations of these two species are the result of recent secondary contact, as predicted under a model of speciation via reinforcement. However, we found no phenotypic evidence of hybridization in natural populations and a complete association between species-specific haplotypes at two different loci (mitochondrial CO I and nuclear EF1-alpha), suggesting little or no contemporary gene flow. Moreover, genealogical and coalescent-based estimates of divergence times and migration rates indicate that, speciation occurred in the distant past. The rapid evolution of wing colour in sympatry is recent, therefore, relative to speciation and seems to be better explained by selection against wasting mating effort and/or interspecific aggression resulting from a 'noisy neighbour' signalling environment.

[Epidural fat in various diseases: contribution of magnetic resonance imaging and potential implications for neuro axial anesthesia]. / La grasa epidural en diferentes patologías. Aportaciones de la resonancia magnética y posibles implicaciones en la anestesia neuroaxial.

Epidural fat is a reservoir of lipophilic substances that cushions the pulsatile movements of the dural sac, protects nerve structures, and facilitates the movement of the dural sac over the periosteum of the spinal canal during flexion and extension. Excessive epidural fat can compress the underlying structures, however, and affect the placement of catheters and the distribution of injected solutions. This review discusses changes in epidural fat related to various diseases and events: lipomatosis, epidural lymphoma, arachnoid cysts, epidural hematoma, meningiomas, angiolipomas, spondylolysis, scoliosis, spinal stenosis, and liposarcoma. Also discussed are the sequencing and protocols for magnetic resonance imaging that enable epidural fat to be observed and distinguished from neighboring structures. The relevance of epidural fat in spinal surgery is considered. Finally, we discuss the possible anesthetic implications of the abnormal deposition of epidural fat, to explain the unexpected complications that can arise during performance of epidural anesthesia.

Nuevas Terapias: Estimulación eléctrica percutánea en dolor lumbar y cervical / New Therapies: Neuromodulation in the treatment of low back and cervical pain

La elevada incidencia y prevalencia del dolor lumbar y del cervical en las sociedades industrializadas hace que se consideren patologías de primer orden en los sistemas sanitarios, ya que además del elevado consumo de recursos sanitarios generan una importante pérdida de horas laborales. Son múltiples las opciones terapéuticas para el tratamiento de estos procesos, planteándose la estimulación eléctrica percutánea (PNT) como una novedad dentro del abanico de posibilidades de tratamiento. Como característica diferencial con otros sistemas de neuromodulación resulta menos invasiva y con un perfil de seguridad y eficacia realmente notable. Presentamos una recopilación de los datos publicados más relevantes que avalan esta técnica y un breve comentario de los resultados preliminares de su utilización en nuestro país

The high incidence and prevalence of low back and cervical pain in industrialized societies ensues its importance for health systems. These conditions generate a high consumption of health resources and a significant loss of working hours. Among the therapeutic options for the treatment of these processes, Percutaneous Neuromodulation Therapy (PNT) is an innovative procedure within the range of therapies available. PNT, unlike other neuromodulation systems, is less invasive and has a considerable safety and efficacy profile. A review of the relevant published data regarding this technique and a brief report on its preliminary results for its use in our country are made