Monopolar protrusive activity: a new morphogenic cell behavior in the neural plate dependent on vertical interactions with the mesoderm in Xenopus

We compared the type and patterning of morphogenic cell behaviors driving convergent extension of the Xenopus neural plate in the presence and absence of persistent vertical signals from the mesoderm by videorecording explants of deep neural tissue with involuted mesoderm attached and of deep neural tissue alone. In deep neural-over-mesoderm explants, neural plate cells express monopolar medially directed motility and notoplate cells express randomly oriented motility, two new morphogenic cell behaviors. In contrast, in deep neural explants (without notoplate), all cells express bipolar mediolateral cell motility. Deep neural-over-mesoderm and deep neural explants also differ in degree of neighbor exchange during mediolateral cell intercalation. In deep neural-over-mesoderm explants, cells intercalate conservatively, whereas in deep neural explants cells intercalate more promiscuously. Last, in both deep neural-over-mesoderm and deep neural explants, morphogenic cell behaviors differentiate in an anterior-to-posterior and lateral-to-medial progression. However, in deep neural-over-mesoderm explants, morphogenic behaviors first differentiate in intervals along the anteroposterior axis, whereas in deep neural explants, morphogenic behaviors differentiate continuously from the anterior end of the tissue posteriorly. These results describe new morphogenic cell behaviors driving neural convergent extension and also define roles for signals from the mesoderm, up to and beyond late gastrulation, in patterning these cell behaviors.     

Modification of the deep pineal after ablation of the superficial epiphysis in the golden hamster]

In various species (among Rodents: Mesocricetus auratus, Cricetus cricetus, Mus musculus, Meriones libycus, M. shawi et M. crassus; among Cheiroptera: Artibeus jamaicensis etc), the pineal complex is formed by two different portions one superficial situated under the cerebral dura and one deep portion situated between the habenular and posterior commissures. Superficial and deep portions are separated by a tractus of fibers and some pineal cells. Superficial epiphysectomy in the Mesocricetus auratus determines an increase in volume of the deep pineal. The nuclear diameter is also enlarged in this case. The functions of both superficial and deep pineal seem to be closely related. Superficial epiphysectomy is not followed by involution or hypoactivity of the deep pineal. Superficial epiphysectomy also determines changes in the subcommissural and subfornical organs.     

Cell Migration and Induction in the Development of the Surface Ectodermal Pattern of the Xenopus laevis Tadpole

The surface of the Xenopus tadpole contains three specialized, transient cell types; the ciliated, hatching gland, and cement gland cells. To distinguish whether the appearance of these cell types on the surface is due to induction of surface cells or due to migration of deep ectodermal cells into the surface, we transplanted labelled surface or deep cells to unlabelled hosts at early to mid-gastrulae. After raising the host to a tadpole (Stage 28), we examined the embryo's surface for ciliated, hatching gland, and cement gland cells, and observed which cells were labelled. We find that all ciliated cells move into the surface from the deep ectodermal layer along with other cells of unknown function. Hatching gland cells arise by induction of surface cells as do the majority of cement gland cells. A few deep cells give rise to cement gland cells. Therefore, migration of deep cells to the surface and localized induction of surface cells contribute to the final surface patterning of the Xenopus tadpole.     

Muscle Fiber Types in the Pectoralis of the White Pelican,a Soaring Bird

The pectoralis muscle (M. pectoralis) of many premier soaring birds contains a smaller, accessory, deep belly in addition to the much larger superficial belly found in all flying birds. Here we describe the muscle fiber types in both the superficial and deep bellies of the pectoralis of one such adept soaring species, the white pelican (Pelecanus erythrorhynchos).Histochemical techniques are used to demonstrate both nicotinamide adenine dinucleotide (reduced) and myofibrillar adenosine triphosphatase activities within the muscle fibers. Immunocytochemical methods employing several monoclonal antibodies, each directed against a different myosin heavy chain epitope of the chicken, are also used to characterize the fibers. While the superficial belly of the muscle consists entirely of fast-twitch oxidative-glycolytic fibers, the deep belly is composed exclusively of slow fibers. These slow fibers are labelled by two different antibodies specific for chicken slow myosin. We suggest that the fibers of the superficial belly are best suited to flapping flight, and that the fibers of the deep belly would be recruited only during soaring flight. Furthermore, we hypothesize that the deep belly found in the pectoralis of soaring species probably evolved from a deep neuromuscular compartment of the superficial belly.     

Species–energy relationship in the deep sea: a test using the Quaternary fossil record

Little is known about the processes regulating species richness in deep‐sea communities. Here we take advantage of natural experiments involving climate change to test whether predictions of the species–energy hypothesis hold in the deep sea. In addition, we test for the relationship between temperature and species richness predicted by a recent model based on biochemical kinetics of metabolism. Using the deep‐sea fossil record of benthic foraminifera and statistical meta‐analyses of temperature‐richness and productivity‐richness relationships in 10 deep‐sea cores, we show that temperature but not productivity is a significant predictor of species richness over the past c. 130 000 years. Our results not only show that the temperature‐richness relationship in the deep‐sea is remarkably similar to that found in terrestrial and shallow marine habitats, but also that species richness tracks temperature change over geological time, at least on scales of c. 100 000 years. Thus, predicting biotic response to global climate change in the deep sea would require better understanding of how temperature regulates the occurrences and geographical ranges of species.     

Light microscopy of the medial wall of the cerebral cortex of the lizard Psammodromus algirus

The telencephalic medial wall of the lizard Psammodromus algirus was studied using Golgi and conventional light microscopic techniques. The area is formed by two different cytological fields—medial cortex and dorsomedial cortex. These two cortices possess three layers dorsoventrally: a superficial plexiform layer, a cellular layer, and a deep plexiform layer. The alveus, a deep fiber system, runs adjacent to the ependyma. Four classes of neurons are found in the cellular layer of the medial cortex on the basis of soma shape, dendritic pattern, and position in the layer: horizontal, double pyramidal, and candelabra cells. Solitary cells are present in the superficial and deep plexiform layers of the medial cortex. Those of the superficial plexiform layer are stellate cells. Horizontal and vertical cells are found in the deep plexiform layer. Double pyramidal cells are the most frequently impregnated in the cellular layer of the dorsomedial cortex. In addition, candelabra cells are present at the lateral end of the layer. Two cell types are found in the deep plexiform layer of the dorsomedial cortex: solitary pyramidal cells and, among the fibers of the alveus, horizontal cells. Ependymal tanycytes line the ventricular surface, and protoplasmic astrocytes are found in the plexiform layers of both medial and dorsomedial cortices.     

Investigating the environmental drivers of deep‐seafloor biodiversity: A case study of peracarid crustacean assemblages in the Northwest Atlantic Ocean

The deep‐sea benthos covers over 90% of seafloor area and hosts a great diversity of species which contribute toward essential ecosystem services. Evidence suggests that deep‐seafloor assemblages are structured predominantly by their physical environment, yet knowledge of assemblage/environment relationships is limited. Here, we utilized a very large dataset of Northwest Atlantic Ocean continental slope peracarid crustacean assemblages as a case study to investigate the environmental drivers of deep‐seafloor macrofaunal biodiversity. We investigated biodiversity from a phylogenetic, functional, and taxonomic perspective, and found that a wide variety of environmental drivers, including food availability, physical disturbance (bottom trawling), current speed, sediment characteristics, topographic heterogeneity, and temperature (in order of relative importance), significantly influenced peracarid biodiversity. We also found deep‐water peracarid assemblages to vary seasonally and interannually. Contrary to prevailing theory on the drivers of deep‐seafloor diversity, we found high topographic heterogeneity (at the hundreds to thousands of meter scale) to negatively influence assemblage diversity, while broadscale sediment characteristics (i.e., percent sand content) were found to influence assemblages more than sediment particle‐size diversity. However, our results support other paradigms of deep‐seafloor biodiversity, including that assemblages may vary inter‐ and intra‐annually, and how assemblages respond to changes in current speed. We found that bottom trawling negatively affects the evenness and diversity of deep‐sea soft‐sediment peracarid assemblages, but that predicted changes in ocean temperature as a result of climate change may not strongly influence continental slope biodiversity over human timescales, although it may alter deep‐sea community biomass. Finally, we emphasize the value of analyzing multiple metrics of biodiversity and call for researchers to consider an expanded definition of biodiversity in future investigations of deep‐ocean life.     

The vascular territories of the superior epigastric and the deep inferior epigastric systems

The vascular territories of the superior and the deep inferior epigastric arteries were investigated by dye injection, dissection, and barium radiographic studies. By these means it was established that the deep inferior epigastric artery was more significant than the superior epigastric artery in supplying the skin of the anterior abdominal wall. Segmental branches of the deep epigastric system pass upward and outward into the neurovascular plane of the lateral abdominal wall, where they anastomose with the terminal branches of the lower six intercostal arteries and the ascending branch of the deep circumflex iliac artery. The anastomoses consist of multiple narrow "choke" vessels. Similar connections are seen between the superior and the deep inferior epigastric arteries within the rectus abdominis muscle well above the level of the umbilicus. Many perforating arteries emerge through the anterior rectus sheath, but the highest concentration of major perforators is in the paraumbilical area. These vessels are terminal branches of the deep inferior epigastric artery. They feed into a subcutaneous vascular network that radiates from the umbilicus like the spokes of a wheel. Once again, choke connections exist with adjacent territories: inferiorly with the superficial inferior epigastric artery, inferolaterally with the superficial circumflex iliac artery, and superiorly with the superficial superior epigastric artery. The dominant connections, however, are superolaterally with the lateral cutaneous branches of the intercostal arteries. For breast reconstruction, it would appear that prior ligation of the deep inferior epigastric artery would be of advantage when elevating the lower abdominal skin on a superiorly based rectus abdominis musculocutaneous flap. The vascularity of this flap would be further increased by positioning some part of the skin paddle over the dense pack of large paraumbilical perforators. Based on these anatomic studies, the relative merits of the superior and deep inferior epigastric arteries with respect to local and distant tissue transfer using various elements of the abdominal wall are discussed in detail.     

Superiority of the deep circumflex iliac vessels as the supply for free groin flaps. Clinical work.

In this paper we present 16 cases of free transfer of compound flaps from the groin, 11 using the deep circumflex iliac vessels as a stem and 5 using the superficial circumflex iliac vessels as a stem. We found the deep vessels superior in many ways to the superficial vessels for this purpose; they are larger, permitting greater ease in anastomoses and providing more reliable blood flow. We believe that larger osteocutaneous or myocutaneous flaps can be transferred on the deep vessels than on the superficial ones-and that the deep circumflex iliac flap may supplant the conventional free going flap in most situations. The method evolved in response to patient need, not for surgical éclat.     

Intraventricular blood vessels associated with the deep pineal gland of the Mongolian gerbil,Meriones unguiculatus

Summary Intraventricular blood vessels and choroidal-like cells were studied using scanning electron microscopy and correlative light microscopy. The intraventricular blood vessels were covered on their ependymal surface with a layer of cells essentially identical to the ependyma of the choroid plexus in the gerbil. Similar choroidal-like cells were seen either singly or in clusters associated with the cerebrospinal fluid-contacting pinealocytes of the suprapineal recess. Processes of the cerebrospinal fluid-contacting pinealocytes were seen extending to and making contact with the choroidal-like cells. The intraventricular blood vessels appeared to be derived from the choroid plexus, and typically took one of three courses in and around the surface of the deep pineal: (1) the vessels or their equivalent were located in the suprapineal recess with no indication of penetration into the substance of the deep pineal; (2) the vessels coursed from the suprapineal recess around the anterior surface of the habenular commissure to enter the ventral surface of the deep pineal; or (3) the vessels entered the parenchyma of the deep pineal from its dorsal surface and could be seen coursing through the substance of the gland. The close association between the choroidal-like cells and the intraventricular blood vessels with the deep pineal gland add morphological support for the possibility of interaction between the cerebrospinal fluid, or perhaps the choroid plexus, and the deep pineal gland.     

Characteristics and underlying mechanisms of plant deep soil water uptake and utilization: Implication for the cultivation of plantation trees

根系吸水是树木水分关系的重要环节, 在树木生理活动中发挥着至关重要的作用。深层土壤中的水资源含量一般相对较高, 常可为树木生长供给大量水分, 并在旱季保障其生存与正常生长。因此, 了解树木对深层土壤水的吸收利用特征与机制, 可帮助深入认识树木与环境的互作机制、树木的生长与生存策略、物种间的共存与竞争机制等内容, 同时还可帮助构建既能降低外部水资源投入, 又能避免水分生态环境负面效应的人工林绿色栽培制度。基于已有研究, 该文对树木吸收利用深层土壤水的特征与机制进行了综述。首先, 探讨了深层根系和深层土壤的界定, 指出对于除寒温带针叶林以外的其他主要森林植被类型, 可以1 m作为树木深根系和深土层的平均划分(参考)标准, 并明确了全球范围内树木深根系的成因。其次, 对已有研究中观察到的树木对深层土壤水的吸收利用特征及其影响因素进行了归纳与总结, 并从深根系性状调节、整株水力特性协调两方面探讨了树木高效吸收利用深层土壤水的机制, 如可通过深根系的空间、时间和效率调节策略来促进对深土层水分的吸收。最后, 提出了树木利用深土层水分对人工林培育的几点启示, 包括水分管理.中应使林木适度利用深层土壤水, 选用合适的灌水频率、合理的树种混交能促进深层土壤水分储库“缓冲”作用的发挥, 基于树木土壤水分利用深度的间伐木选择技术等, 并指出了该领域现有研究的不足以及今后的发展方向。     

Morphological divergence between three Arctic charr morphs – the significance of the deep‐water environment

Morphological divergence was evident among three sympatric morphs of Arctic charr (Salvelinus alpinus (L.)) that are ecologically diverged along the shallow‐, deep‐water resource axis in a subarctic postglacial lake (Norway). The two deep‐water (profundal) spawning morphs, a benthivore (PB‐morph) and a piscivore (PP‐morph), have evolved under identical abiotic conditions with constant low light and temperature levels in their deep‐water habitat, and were morphologically most similar. However, they differed in important head traits (e.g., eye and mouth size) related to their different diet specializations. The small‐sized PB‐morph had a paedomorphic appearance with a blunt head shape, large eyes, and a deep body shape adapted to their profundal lifestyle feeding on submerged benthos from soft, deep‐water sediments. The PP‐morph had a robust head, large mouth with numerous teeth, and an elongated body shape strongly related to their piscivorous behavior. The littoral spawning omnivore morph (LO‐morph) predominantly utilizes the shallow benthic–pelagic habitat and food resources. Compared to the deep‐water morphs, the LO‐morph had smaller head relative to body size. The LO‐morph exhibited traits typical for both shallow‐water benthic feeding (e.g., large body depths and small eyes) and planktivorous feeding in the pelagic habitat (e.g., streamlined body shape and small mouth). The development of morphological differences within the same deep‐water habitat for the PB‐ and PP‐morphs highlights the potential of biotic factors and ecological interactions to promote further divergence in the evolution of polymorphism in a tentative incipient speciation process. The diversity of deep‐water charr in this study represents a novelty in the Arctic charr polymorphism as a truly deep‐water piscivore morph has to our knowledge not been described elsewhere.     

A microscopic study of the marmoset claw and nail

W. E. Le Gros Clark concluded in his study of the problem of the primate claw that the essential difference between claw and nail is the presence of a terminal matrix associated with a deep layer in the claw, whereas neither terminal matrix nor deep layer exists in the nail. He demonstrated that the marmoset claw (which tips every digit except the hallux) has a thin deep layer and a recognizable terminal matrix. The present paper reports and discusses evidence that the marmoset nail also has a deep layer and terminal matrix. Although the importance of these structures in the claw is not disputed, it appears that these can no longer be considered absolute differences between claw and nail. On the basis of this evidence, it cannot be claimed that the presence of the deep layer and terminal matrix determines the distinctive shape of the claw as opposed to the nail.     

Reflections on the Conservation and Sustainable Use of Genetic Resources in the Deep Seabed Beyond the Limits of National Jurisdiction

Attention is increasingly being given to genetic resources in the deep seabed beyond the limits of national jurisdiction owing to their considerable potential scientific and economic value. At the same time, there are concerns that the increased demand for these genetic resources may result in their unsustainable collection or even in the extinction of species in the deep seabed. At present there is no specific legal framework governing these resources in international law. Thus, this article explores the relevant rules of international law applicable to the conservation and sustainable use of genetic resources in the deep seabed.     

Marine science in the age of sail

Contrary to commonly expressed opinion, scientific interest in the deep ocean did not begin in the second half of the nineteenth century with the famous cruise of HMS Challenger . However, before the widespread use of steam power, any would-be deep sea scientist had a number of difficulties to overcome. This paper explores a few of the more obvious ones that probably explain why, prior to the Challenger voyage, attempts at deep ocean science were generally small scale, uncoordinated — and largely unsuccessful!     

Live demonstration of microcirculation in the deep fascia and its implication

The rich vascular network in the deep fascia has been emphasized by various scientists, but the actual demonstration of live circulation in the deep fascia has not previously been witnessed. Encouraged by the sight of live circulation in the web membrane of toad hind limb, a successful attempt was made to demonstrate the live circulation in the vascular network of the deep fascia. Fascial extensions of inferiorly based fasciocutaneous flaps were dissected in five patients with distal leg and heel defects. The fascial extension in continuity with a proximal retrograde fasciocutaneous flap was mounted on a glass slide and examined under a microscope. The authors witnessed the live microcirculation and the movement of individual red blood corpuscles in vascular channels of the deep fascia. The authors also noticed that the deep fascia has two layers with circulations that are independent of one other. A video recording was made to document these important features.     

The relationship of the superficial and deep facial fascias: relevance to rhytidectomy and aging.

Controversy persists regarding the relationship of the superficial facial fascia (SMAS) to the mimetic muscles, deep facial fascia, and underlying facial nerve branches. Using fresh cadaver dissection, and supplemented by several hundred intraoperative dissections, we studied facial soft-tissue anatomy. The facial soft-tissue architecture can be described as being arranged in a series of concentric layers: skin, subcutaneous fat, superficial fascia, mimetic muscle, deep facial fascia (parotidomasseteric fascia), and the plane containing the facial nerve, parotid duct, and buccal fat pad. The anatomic relationships existing within the facial soft-tissue layers are (1) the superficial facial fascia invests the superficially situated mimetic muscles (platysma, orbicularis oculi, and zygomaticus major and minor); (2) the deep facial fascia represents a continuation of the deep cervical fascia cephalad into the face, the importance of which lies in the fact that the facial nerve branches within the cheek lie deep to this deep fascial layer; and (3) two types of relationships exist between the superficial and deep facial fascias: In some regions of the face, these fascial planes are separated by an areolar plane, and in other regions of the face, the superficial and deep fascia are intimately adherent to one another through a series of dense fibrous attachments. The layers of the facial soft tissue are supported in normal anatomic position by a series of retaining ligaments that run from deep, fixed facial structures to the overlying dermis. Two types of retaining ligaments are noted as defined by their origin, either from bone or from other fixed structures within the face.(ABSTRACT TRUNCATED AT 250 WORDS)     

The palaeopsychrosphere in the Devonian

The interpretation of Palaeozoic marine benthonic ostracods of the Thuringian ‘Ecotype’ or ‘Mega‐assemblage’ as indicative of a palaeopsychrosphere has been controversial. We review the evidence and conclude that the characteristics and distribution of these ostracods are consistent with the existence of deep, cold, well‐oxygenated water masses, formed by high‐latitude sinking of surface waters, in the Devonian oceans, comparable with those of the modern ocean that constitute the psychrosphere (waters below the thermocline with temperature <10°C). We present a new palaeoceanographic model for the Frasnian–Famennian (Late Devonian) Kellwasser events that resulted in the extinction of 75% of marine ostracod taxa, mostly neritic or pelagic forms, while the deep water Thuringian Mega‐assemblage was relatively unaffected. We offer an explanation for the unlikely preservation of examples of such a deep water (bathyal to abyssal) ostracod fauna that involves upwelling of deep cold waters on continental margins.