Narrow Lamina Research Articles

A new species of grass fern, Schizaea erecta (Schizaeaceae), from Dinagat Island, Mindanao, Philippines

Schizaea erecta Amoroso & Coritico (Schizaeaceae) from Dinagat Island, Mindanao, Philippines, is here described. This species is distinguished from other species of Schizaea by its consistently erect sterile and fertile fronds, narrow laminae, opposite sorophore lobes, rhizomes covered with short appressed brown scales, and oblong sporangia with apical annulus and conspicuous long, white hairs. A taxonomic key to the species of Philippine Schizaeaceae is provided.

Nepenthes limiana (Nepenthaceae), a new pitcher plant from the northern Titiwangsa Range of Peninsular Malaysia

Nepenthes limiana, a pitcher plant from the northern Titiwangsa Range of Peninsular Malaysia, is described as new. It is the northernmost known species of the recently defined N. macfarlanei group, whose members are characterised by the presence of conspicuous hairs on the lower surface of the lid. It differs from other members of this group in exhibiting adaptations to seasonal drought in the form of thickened roots and narrow laminae that are reminiscent of those produced by the pyrophytic Nepenthes of Indochina and northernmost Malaysia. Coupled with the presence of decurrent leaf bases, which are not present in any other N. macfarlanei group species but which are present in the pyrophytic Nepenthes, these characters could indicate either morphological convergence or an as yet uncharacterised relationship between N. limiana and the Nepenthes species of Indochina.

<p align="left"><strong><em>Selliguea wusugongii</em> (Polypodiaceae), a new fern species from southeastern Xizang, China based on morphological and molecular evidence</strong></p>

A new fern species, Selliguea wusugongii (Polypodiaceae), is described from southeastern Xizang, China. Morphologically, S. wusugongii is distinguished in the genus by having long need-like fronds with width of the lamina only 0.8–1.1 mm, and is the species with the narrowest laminae in selligueoid ferns. The new species is most similar to some Malay selligueoid ferns in morphology, S. bisulcata and S. subsparsa for example, by having simple fronds, narrow laminae and marginal rounded sori, but differs from them in having considerably more scattered scales, frond monomorphic and up to 40 cm long. A phylogenetic analysis based on five plastid markers supported the new species as most closely related to S. rhynchophylla. However, the two species are different from each other in quite a few morphological characteristics, such as the size of fronds and the visibility of venation, and the position of sori.

Macromitrium larrainii, a New Species ofMacromitrium(Orthotrichaceae, Bryophyta) from New Caledonia

The moss Macromitrium larrainii sp. nov. from Mt Panie, the highest summit of New Caledonia, is described and illustrated. This species is characterised by 1) the hairy appearance of branches due to the long aristate leaves arranged irregularly, not spirally, 2) the narrow leaf lamina asymmetrical above, 3) leaf cells consistently smooth, and 4) upper leaf cells irregular in shape and basal ones linear with a straight lumen. Comparison with similar Macromitrium species in neighbouring countries confirms that it is a new species, likely endemic.

Evidence of a New Carcharodontosaurid from the Upper Cretaceous of Morocco

We report an isolated frontal of a large-bodied theropod from the Cenomanian “Kern Kern beds” of Morocco with an unusual morphology that we refer to a new carcharodontosaurid distinct from the sympatric Carcharodontosaurus. The specimen shows an unique combination of plesiomorphic and potentially autapomorphic features: very thick and broad bone with a complex saddle-shaped dorsal surface, and a narrow vertical lamina between the prefrontal and lacrimal facets. This study supports the hypothesis that a fourth large theropod was present in the Cenomanian of Morocco together with Carcharodontosaurus, Deltadromeus, and Spinosaurus.

Eternal youth, the fate of developing Arabidopsis leaves upon Rhodococcus fascians infection.

The phytopathogenic actinomycete Rhodococcus fascians induces neoplastic shooty outgrowths on infected hosts. Upon R. fascians infection of Arabidopsis (Arabidopsis thaliana), leaves are formed with small narrow lamina and serrated margins. These symptomatic leaves exhibit reduced tissue differentiation, display more but smaller cells that do not endoreduplicate, and accumulate in the G1 phase of the cell cycle. Together, these features imply that leaf growth occurs primarily through mitotic cell division and not via cell expansion. Molecular analysis revealed that cell cycle gene expression is activated continuously throughout symptomatic leaf development, ensuring persistent mitotic cycling and inhibition of cell cycle exit. The transition at the two major cell cycle checkpoints is stimulated as a direct consequence of the R. fascians signals. The extremely reduced phenotypical response of a cyclind3;1-3 triple knockout mutant indicates that the D-type cyclin/retinoblastoma/E2F transcription factor pathway, as a major mediator of cell growth and cell cycle progression, plays a key role in symptom development and is instrumental for the sustained G1-to-S and G2-to-M transitions during symptomatic leaf growth.

Transdural approach for calcified central disc herniations of the upper lumbar spine

Disc herniations of the upper lumbar spine (L1-2 and L2-3) have a frequency of 1 to 2% of all disc herniations. During posterior discectomy after laminectomy, significant manipulation of the exiting nerve root is unavoidable because of the narrow lamina and the difficulty in mobilizing the nerve root. The authors adopted a transdural approach in patients with calcified central disc herniation at the L1-2 level to reduce the risk of nerve root injury. Four patients suffering from radiating pain together with back pain were treated using the transdural approach. Preoperative neuroimaging studies revealed severe central disc herniation with calcification at the L1-2 level. After laminectomy or laminotomy, the incised dura mater was tacked, and the cauda equina rootlets were gently retracted. An intentional durotomy was performed over its maximal bulging of the ventral dura. After meticulous dissection of dense adhesions between the disc herniation and the dural sac, adequate decompression with removal of calcified disc fragments and osteophytes was accomplished. Clinical symptoms improved in all patients. Postoperative permanent cerebrospinal fluid leakage and pseudomeningocele were not observed, and no patient had a progressive lumbar deformity at an average follow-up of 53 months. Transient mild motor weakness and sensory change were observed in two patients postoperatively; however, these symptoms resolved completely within 1 week. The posterior transdural approach offers an alternative in central calcified upper lumbar disc herniation when root retraction is dangerous.

Laminar inputs from dorsal cochlear nucleus and ventral cochlear nucleus to the central nucleus of the inferior colliculus: Two patterns of convergence

The central nucleus of the inferior colliculus is a laminated structure composed of oriented dendrites and similarly oriented afferent fibers that provide a substrate for tonotopic organization. Although inputs from many sources converge in the inferior colliculus, how axons from these sources contribute to the laminar pattern has remained unclear. Here, we investigated the axons from the cochlear nuclei that terminate in the central nucleus of the cat and rat. After characterization of the best frequency of the neurons at the injection sites in the cochlear nucleus, the neurons were labeled with dextran in order to visualize their axons and synaptic boutons in the central nucleus. Quantitative methods were used to determine the size and distribution of the boutons within the laminar organization. Two components in the laminae were identified: (1) a narrow axonal lamina that included the largest fibers and largest boutons; (2) a wide axonal lamina, surrounding the narrow lamina, composed of thin fibers and only small boutons. The wide lamina was approximately 30–40% wider than the narrow lamina, and it often extended more than 100μm beyond the larger boutons on each side. The presence of both thick and thin fibers within the acoustic striae following these injections suggests that large and small fibers/boutons within these bands may originate from different neuronal types in the dorsal and ventral cochlear nucleus. We conclude that the narrow laminae that contain large fibers and boutons originate from larger cell types in the cochlear nucleus. In contrast, the wide lamina composed exclusively of small boutons may represent an input from other, perhaps smaller neurons in the cochlear nucleus. Thus, two types of inferior colliculus laminar structures may originate from the cochlear nucleus, and the small boutons in the wide laminae may contribute a functionally distinct input to the neurons of the inferior colliculus.

Excess chromium alters uptake and translocation of certain nutrients in citrullus

Citrullus plants were grown in refined sand with varying levels of chromium to determine their tolerance limit to excess chromium. The plants were maintained in control nutrient solution for 24 days and on the 25th day chromium as dichromate was added at 0.05, 0.1, 0.2, 0.3 and 0.4 mM. A control set of plants was grown in the same nutrient solution without chromium. At chromium levels >0.2 mM plants showed growth depression, with chlorosis and loss of turgor of middle leaves. Affected leaves had narrow lamina; tendrils were thin, short and did not have coiling property. Later chlorosis became severe and changed to necrosis in patches. Petiole along with lamina became wilted, rugged and hung down due to complete loss of water. At lower chromium concentration, (0.05, 0.1 and 0.2 mM) only depression in growth was observed. With increase in chromium concentration of nutrient solution accumulation of chromium in different parts of Citrullus was increased. Increase in concentrations of phosphorus, manganese and decrease in iron, copper, zinc and sulphur were observed in leaves. Toxicity of chromium was greater at 0.2–0.4 mM, compared to lower concentrations. Threshold of toxicity and toxicity of Cr in old leaves were, respectively, 0.9 and 3.9 μg g −1 dry matter of citrullus.

A new lycopsid megaspore cone from the Upper Devonian of Chaohu, China

A new small lycopsid cone, Minostrobus chaohuensis gen. et sp. nov., is described from the upper part of Wutung Formation (Famennian) of Chaohu, Anhui, China. Six sporophylls in each whorl are tightly arranged on the cone axis. Each sporophyll consists of a short pedicel and a narrow lamina with smooth margins. One spherical to spherical-ellipsoidal sporangium is attached directly to the adaxial surface of each sporophyll. Each sporangium contains four megaspores. A solid exarch protostele occurs at the centre of the cone axis, and a mesarch protostele in the base of the sporophyll. M. chaohuensis is interpreted as a small, herbaceous, heterosporous lycopsid.

A new lycopsid megaspore cone from the Upper Devonian of Chaohu, China

A new small lycopsid cone, Minostrobus chaohuensis gen. et sp. nov., is described from the upper part of Wutung Formation (Famennian) of Chaohu, Anhui, China. Six sporophylls in each whorl are tightly arranged on the cone axis. Each sporophyll consists of a short pedicel and a narrow lamina with smooth margins. One spherical to spherical-ellipsoidal sporangium is attached directly to the adaxial surface of each sporophyll. Each sporangium contains four megaspores. A solid exarch protostele occurs at the centre of the cone axis, and a mesarch protostele in the base of the sporophyll. M. chaohuensis is interpreted as a small, herbaceous, heterosporous lycopsid.

Structure and Formation of the Egg Capsule Tendrils in the Dogfish Scyliorhinus canicula

The tendrils of the egg capsule of the dogfish Scyliorhinus canicula appear to act as damped springs which become entagled with one another, attaching the capsule firmly to the seaweed Halidrys siliquosa. The present paper describes the structure of tendrils and their method of formation in a specialized region of the nidamental gland which we have termed the tendril-forming region (TFR). The tendrils provide a unique system for studying the assembly of a complexly ordered collagenous material. Tendrils show primary twisting and then undergo secondary helical coiling. In cross section they have a lamellated, spiral construction. Each lamella appears to consist of a broad and a narrow lamina. Collagen fibril orientation is approximately longitudinal in the broad lamina and approximately circumferential in the narrow one. Fine, longitudinal fluid-filled canaliculi lie between the lamellae and may act as shock absorbers. Spherical granules containing a high concentration of tyrosine residues are present in large numbers in the outermost lamellae and may have rubber-like properties. The collagen is probably heavily cross-linked and gives the tendril high tensile strength. The tendril appears to be formed from the adhesion of successive lamellae which are wrapped round a central core as the forming tendril undergoes counter-clockwise (left-handed) rotation within the TFR. The latter appears to represent a modification of the structure of the simpler capsule wall-forming region (CWFR). A wave of progressive activation of tubular glands of the TFR travelling anteriorly followed by a wave of deactivation in the opposite direction appears to be responsible for the secretion of first the posterior tendril, then the marginal rib of the egg capsule and finally the anterior tendril. Secreted material passes from glandular tubules through secretory ducts to a series of parallel transverse grooves which act as complex extrusion dies to form the lamellae of the tendril. We have gone some way towards describing how the complex three-dimensional organization of the tendril is produced by these dies. Observations suggested the following sequence of events within the extrusion dies: secreted material becomes uniaxially oriented in the secretory duct and is then passed between ciliated plates we have termed `baffle plates'. These separate the material into an anterior flow containing vertically oriented collagen molecules and a thinner posterior flow containing approximately horizontally oriented ones. These two flows then pass through a transverse groove to become respectively the broad and the narrow lamina of a single lamella of the tendril. The lamellae become pleated within the transverse grooves probably by anisotropic shrinkage. The canaliculi appear to be formed by the partial adhesion of the pleated lamellae as they are wound onto the forming tendril by rotation within the TFR. The mechanism of rotation of the forming thread and its subsequent coiling in the posterior oviduct is discussed.

Über den Verlauf der Leitbündel in die Blattspreite bei der Gattung Allium L.

Summary Different orientation of vascular bundles can be found in laminae of genus Allium. Six different modes of connections between the vascular bundles of the sheath and those of the lamina were described. Type A is present in the Old World species as well as in the New World species of subgenus Amerallium , and in the species of subgenus Bromatorrhiza. Type B is especially characteristic for the sections Cepa and Schoenoprasum but can also be found in the other species belonging to several sections of the subgenera Allium and Rhizirideum. Type C is also widely distributed over the subgenera Rhizirideum and Allium. Type D is most typical for the section Allium , but is also present in the sections Rhizirideum and Petroprason. Type E is the most variable one and can be found in all sections of subgenus Allium and in several groups of subgenus Rhizirideum , as well as in section Porphyroprason of subgenus Melanocrommyum. Rather narrow laminae of type A are regarded to be the most primitive structure from which all other types could have evolved. The types B, D, and E are probably only ontogenetic variants of one evolutionary line, though the types A (for the case of broadleaved species) and F represent two more evolutionary lines. Type C has only been found in species having a reduced lamina and is deducible from most of the other types.

Granule cell dispersion in the dentate gyrus of humans with temporal lobe epilepsy

The distribution of granule cells in the dentate gyrus of the hippocampal formation was studied in control autopsy and temporal lobe epilepsy (TLE) specimens. In control tissue, the granule cell somata were closely approximated and formed a narrow lamina with a distinct, regular border with the molecular layer. In 11 of 15 TLE specimens, the granule cell somata were dispersed and formed a wider than normal granule cell layer. The granule cell somata extended into the molecular layer to varying extents, creating an irregular boundary between the lamina. The dispersed granule cells were frequently aligned in columns, and many of these neurons displayed elongated bipolar forms. The extent of granule cell dispersion appeared to be related to the amount of cell loss in the polymorph layer of the dentate gyrus. Granule cell dispersion was not consistently associated with granule cell loss although 5 of the 11 specimens with granule cell dispersion also showed moderate to marked granule cell loss. The most common features in the histories of the TLE cases with granule cell dispersion were severe febrile seizures or seizures associated with meningitis or encephalitis during the first 4 years of life. The dispersion of the granule cells suggest that there has been some alteration in the patterns of cell migration in a subpopulation of cases with severe TLE. The resultant ectopic positions of the granule cells could lead to changes in both the afferent and efferent connections of these neurons and, thus, contribute to the altered circuitry of the hippocampal formation in TLE.

Retinal projections in two Australian polyprotodont marsupials: kowari, Dasyuroides byrnei, and fat-tailed dunnart, Sminthopsis crassicaudata (Dasyuridae).

Retinal projections were examined in two small dasyurids, the kowari and the fat-tailed dunnart, following injections of 3H-proline into one eye. In both animals retinal fibres terminate in the dorsal and ventral lateral geniculate nuclei (LGd, LGv), the lateral posterior nuclear complex, the pretectum, the superior colliculus, the suprachiasmatic nucleus of the hypothalamus and the nuclei of the accessory optic system. The lateroposterior thalamic complex and the accessory optic nuclei receive projections from the contralateral eye only; the remaining centres receive bilateral inputs. Both LGd contain an undifferentiated beta or medial segment and an alpha or lateral segment that comprises further cellular sublaminae, 4 in the kowari and 3 in the dunnart. There is substantial overlap of crossed and uncrossed terminals in both segments, though in each animal a narrow cell lamina next to the optic tract receives only crossed projections and the lateral part of the beta segment receives only uncrossed projections. There is a cell-sparse zone within the alpha segment that receives a predominately uncrossed projection in the kowari and a crossed projection in the dunnart. In both marsupials the density of crossed and uncrossed terminals is equal, a feature of dasyurid quolls but not of another dasyurid, the Tasmanian devil. Additionally, retinal terminals do not form dense clusters within the LGd neuropil. This feature is characteristic of quolls, but not of other mammals, marsupial or placental, all of which display LGd terminal clusters. These findings suggest that the functional organisation of the LGd in these dasyurids may differ from that found in other marsupials.

Proliferation of thalamic afferents in cerebral cortex altered by callosal deafferentation

In area 41, the auditory region of rat neocortex, callosal afferents project to layers I through III and thalamic afferents project to deep layer III through IV. Thus, these two extrinsic systems of afferents project simultaneously to only a narrow lamina in mid to low layer III. For this study, this narrow region of overlap is quantitatively examined to determine the distribution of callosal and thalamic afferents by observing degenerating terminals produced by separate callosal and thalamic lesions. The results show that of all asymmetric synapses observed in the neuropil of this narrow zone, 84% are dendritic spines and the balance are dendritic shafts. Although both callosal and thalamic afferents prefer to synapse with dendritic spines in the neuropil, 78% of the thalamic afferents synapse with dendritic spines while 93% of the callosal afferents synapse with dendritic spines. Vaughan & Foundas (1982) have shown that 3 months after callosal lesions in 1-month-old animals, additional thalamic axons have grown into, and proliferated in, this part of mid to low layer III. Quantitative analysis of the distribution of the degenerating thalamic axon terminals in these long-term callosally lesioned animals has been used to determine whether the proliferating thalamic afferents demonstrate any specificity in the pattern of synapses they make or whether the callosally deafferented neurons determine the pattern of synapses. The results indicate that thalamic axons do exhibit axon specificity, for after they have proliferated into the callosal domain, 80% of the degenerating terminals synapse with dendritic spines and 20% synapse with shafts. This distribution is most comparable to the normal distribution of thalamic axons in this region.

The postcranial skeletons of the Triassic mammals Eozostrodon, Megazostrodon and Erythrotherium.

The purposes of this monograph are to describe the postcranial skeletons of the earliest known mammals, and to probe, in so far as possible by osteological study, biological questions concerning the habits and adaptations of these late Triassic forms. In this context, information on the background of this investigation is useful. Studies of Mesozoic mammals, begun some 150 years ago, are based on rare and fragmentary fossils, principally jaws and teeth. These investigations have yielded a bare outline of some 120 million years of mammalian evolution-about two-thirds of mammalian history. No assessment of the important biological changes occurring during this time can ever be complete, but major advances are possible as new discoveries provide material that is more complete or that represents a previously unknown evolutionary stage. So tenuous is the evidence that at least some concepts are re-evaluated with each discovery. Postcranial anatomy offers especially intriguing prospects for investigation because associated material (that can be positively assigned to a taxon below subclass) has been for the most part unknown, and indeed even dissociated bones are a rarity. Since G.G. Simpson's monographs of 1928 and 1929, progress in the study of Mesozoic mammals has been largely dependent on new finds. A major impetus to renewed investigation came from the discoveries of Mesozoic mammals by Walter Kühne in 1939 and during the immediate post-war years. Kühne first worked on fissures in the Carboniferous limestone quarries at Frome, Somerset, in southwest England where he collected a series of teeth of the problematical form Haramiya and two triconodont teeth which were placed in the genus Eozostrodon (Parrington 1941, 1946). The fissure faunas are generally thought to be of Upper Triassic (Rhaetic) age (Kühne 1946), although Kermack, Musset & Rigney (1973) believe that the evidence is insufficient to determine whether the deposits are Rhaetic or Lower Liassic. After the war Kühne carried his explorations farther west, eventually reaching the quarries at Bridgend in Glamorgan, Wales, where he not only found more triconodont teeth in some quantity (Kühne 1958) but also a symmetrodont tooth (Kühne 1950). Shortly after making these discoveries, Kühne returned to Germany and the work was continued by a team from University College, London, under the leadership of Dr K.A. Kermack.

The morphology of retinal neurons of the owl monkey Aotes.

AbstractThe morphology of photoreceptor, horizontal, bipolar and amacrine cells of the owl monkey (Aotes) is described from retinal whole mounts and cross sections stained with the method of Golgi (Colonnier modification).Rods and cones were often seen and resemble the photoreceptors of other primates. Cone density may be as great as 6400/mm2. Horizontal cells in the area centralis are larger and contact more cones than is the case with rhesus. Peripheral horizontal cells of Aotes are similar to those of rhesus. Midget bipolar cells are common and, even in the area centralis, usually have two basal dendrites. Only midget bipolars with invaginating terminals were clearly identified. Rod and flat bipolars were clearly identified and resembled those of rhesus. A “diffuse” bipolar is described which may represent a variant of either rod or flat bipolar. Some of these cells had dendritic spreads greater than 60 μ. Such bipolar cells have not been described in other primates. Amacrine cells were similar to those of rhesus except that those with coarse processes were all diffuse, i.e., their processes extended vertically through the IPL; those with fine processes were all stratified; their processes were restricted to a narrow lamina of the IPL.

The Genus Fissidens in Puerto Rico

Eustichia C. Muell. Syn. 1' 42. 1849 (in part). Plants slender, bright to yellowish green, more or less gregarious and silky; stems simple, stiff, radiculose and bulblike at base, central strand present; leaves closely imbricated, distichous, keeled, smooth, with a very narrow dorsal lamina not reaching the base; costa vanishing at or near the apex except in the abruptly long subulate-acuminate perichaetial leaves. Dioicous; seta shorter than the perichaetial leaves; capsule globular to obovate, smooth, peristome and annulus lacking; operculum slightly convex and rostrate; calyptra smooth, covering about 13 of the urn, cucullate. Type species, B. norvegicum.