Pericentral Cells Research Articles

TAXONOMY AND PHYLOGENY OF OSMUNDEA (RHODOMELACEAE, RHODOPHYTA) IN ATLANTIC EUROPE.

Two species of Osmundea Stackhouse (Rhodomelaceae, Rhodophyta) that occur in Atlantic Europe have been confused under the names Osmundea ramosissima (Oeder) Athanasiadis and Osmundea truncata (Kützing) Nam et Maggs, regarded until now as a synonym of O. ramosissima. An epitype from its type locality (Stavanger, Norway) is selected for Osmundea ramosissima Athanasiadis, recognized here as a valid name for Fucus ramosissimus Oeder, nom. illeg. Details of vegetative and reproductive morphology of O. ramosissima are reported, based on material from France, the British Isles, and Helgoland. Osmundea ramosissima resembles other species of Osmundea in its vegetative axial segments with two pericentral cells and one trichoblast, spermatangial development from apical and epidermal cells (filament type), the formation of five pericentral cells in the procarp-bearing segment of the female trichoblast, and tetrasporangial production from random epidermal cells. Among the species of Osmundea, O. ramosissima is most similar to O. truncata. Both species have discoid holdfasts, secondary pit connections between epidermal cells, and cup-shaped spermatangial pits. They differ in that: (a) O. ramosissima lacks lenticular wall thickenings and refractive needle-like inclusions in medullary cells, both of which are present in O. truncata; (b) O. ramosissima has branched spermatangial filaments that terminate in a cluster of several cells, whereas in O. truncata the unbranched spermatangial filaments have a single large terminal sterile cell; and (c) cystocarps of O. ramosissima lack protuberant ostioles but ostioles are remarkably protuberant in O. truncata. Phylogenetic analyses of rbcL sequences of Laurencia obtusa (Hudson) Lamouroux and all five Atlantic European species of Osmundea, including the type species, strongly support the generic status of Osmundea. Osmundea ramosissima and O. truncata are closely related (5.2% sequence divergence) and form a well-supported clade sister to a clade consisting of O. pinnatifida (Hudson) Stackhouse, O. osmunda Stackhouse and O. hybrida (A. P. de Candolle) Nam. The formation of secondary pit connections between epidermal cells is a synapomorphy for the O. ramosissima+O. truncata clade. The close relationship between species with cup-shaped spermatangial pits (Osmundea hybrida) and urn-shaped pits (Osmundea pinnatifida and Osmundea osmunda) shows that spermatangial pit shape is not an important phylogenetic character. Parsimony analysis of a morphological data set also supports the genus Osmundea but conflicts with the molecular trees in infrageneric relationships, placing O. hybrida basal within the Osmundea clade and grouping O. osmunda and O. pinnatifida but not O. truncata and O. ramosissima. A key to Osmundea species is presented.

Reappraisal of the type species of Polysiphonia (Rhodomelaceae, Rhodophyta)

The genus Polysiphonia Greville, nom. cons., has had a long and confused nomenclatural history. At present, Polysiphonia has a wide circumscription, including at least 200 species, but it is heterogeneous in many vegetative and reproductive developmental features. Central to any re-evaluation of the genus is a detailed examination of the type species of Polysiphonia, P. urceolata (Lightfoot ex Dillwyn) Greville, which is conspecific with P. stricta (Dillwyn) Greville. We here report on the vegetative and reproductive morphology of P. stricta, including P. urceolata, based on type and other material from the British Isles. Thalli consist of prostrate and erect ecorticate axes with four pericentral cells, attached by unicellular rhizoids remaining in open connection with pericentral cells. Prostrate axes lack vegetative trichoblasts ; trichoblasts occur seasonally on erect axes. Branch initials are cut off from the subapical cell at intervals of four or five segments in dichotomous and alternating pairs rather than being formed from each axial cell in the spiral pattern typical of most species of Polysiphonia. Spermatangial branch initials, which are trichoblast homologues, are produced directly from each axial cell at the tips of erect branches, not subtended by trichoblasts, and have two- to five-celled sterile tips when mature. The mature carpogonial branch is four-celled with a two-celled first sterile group and a one-celled second sterile group. Following presumed fertilization, direct fusion apparently takes place between carpogonium and auxiliary cell; mature cystocarps are usually urceolate. Tetrasporangia are formed from the third pericentral cell, in straight series, and have two pre-sporangial cover cells. Previous accounts of a third, post-sporangial cover cell could not be substantiated. P. stricta and a small group of other Polysiphonia species differ in several important respects from most members of the genus, which have rhizoids cut off from pericentral cells by a cell division, abundant trichoblasts, spirally arranged tetrasporangia and a post-sporangial cover cell. The branching pattern of P. stricta highlights the difficulties of distinguishing between the tribes Polysiphonieae and Pterosiphonieae.

A Detailed Morphological Study of the Type Species of Osmundea (Rhodomelaceae, Rhodophyta)

Details of vegetative and reproductive development of Osmundea osmunda (S. G. Gmelin) Nam et Maggs (Rhodomelaceae, Rhodophyta), the type species of the resurrected genus Osmundea Stackhouse, are presented based on an examination of liquid-preserved and herbarium specimens collected from the British Isles. Each axial segment bears one trichoblast and two pericentral cells on either side of basal cell of the trichoblast. Spermatangial development follows the typical filament type in which spermatangial filaments derive from apical and epidermal cells in pocket-shaped pits with ostiole-like upper openings. Procarp-bearing segments of female trichoblasts have five pericentral cells, of which the fifth acts as the supporting cell of the carpogonial branch. Tetrasporangia are produced from random epidermal cells in apical pits of branchlets, and are arranged parallel to the stichidial axis. Two presporangial cover cells also exhibit parallel arrangement to the stichidial axis as seen in surface view. Among the known Osmundea species, O. osmunda is characterized by having a strongly compressed thallus with distichous branching, a discoid holdfast, lack of secondary pit connections between epidermal cells, presence of lenticular medullary thickenings, non-palisade-like arrangement of epidermal cells in a transverse section of branchlets, pocket-shaped spermatangial pits in adaxial series between a branchlet and its parent axis, clustering terminal sterile cells in spermatangial filaments, procarp-bearing segments with five pericentral cells in female trichoblasts and cystocarps with non-protuberant ostioles. A discussion on phylogenetic implications of these vegetative and reproductive features is also included.

Vegetative and reproductive development of Laurencia venusta (Ceramiales, Rhodophyta)

The previously unknown vegetative and reproductive development of Laurencia venusta Yamada (Ceramiales, Rhodophyta) were studied based on specimens collected from Korea and Japan. Each vegetative axial segment bears a trichoblast and four pericentral cells; the first of the latter is always produced below the basal cell of the trichoblast; the second pericentral cell is formed at some distance from the first, followed by the third and fourth pericentral cells in an alternating sequence. Spermatangial branches are produced from one of two laterals on the suprabasal cell of a trichoblast in cup-shaped spermatangial pits. The procarp-bearing segment of the female trichoblast has five pericentral cells, of which the fifth becomes the supporting cell of the carpogonial branch. Mature cystocarps are ovoid with a non-protuberant ostiole. Tetrasporangia, with two pre- and one post-sporangial cover cells, are produced abaxially from the existing third and fourth pericentral cell, or occasionally only the fourth pericentral cell, and are parallel to the stichidial axis. Two pre-sporangial cover cells are aligned transversely to the stichidial axis in surface view. These features confirm the placement of L. venusta in the revised Laurencia Lamouroux. Laurencia venusta is characterized by a loosely intricate, small thallus without percurrent axis, numerous holdfasts from the creeping and coalesced basal branches, and abundant medullary lenticular thickenings. Furthermore, it seems to be distinct from other species in having a single, comparatively large (20–30 μm diam.) corps en cerise per epidermal cell.

Morphological and taxonomic studies of selected genera from the tribe Amansieae (Rhodomelaceae, Rhodophyta)

The morphology and taxonomy of seven poorly understood species from five genera of the Amansieae are documented. The basic characters by which genera of the tribe are currently distinguished include: (1) the number of pericentral cells; (2) the degree of thallus flattening and lateral wing development; (3) the type of endogenous branching; (4) branch and/or spine features of blade margins; and (5) the position of reproductive axes. Two Australian species of Enantiocladia Falkenberg, E. robinsonii (J.Agardh) Falkenberg and E. axillaris Falkenberg, do not conform to the defining features of Enantiocladia as exhibited by specimens of the type species examined in this study, and the two new genera Plectrophora and Nanopera are proposed to accommodate them. The genusKuetzingia Sonder has previously included four species, the three Australian endemics K. canaliculata (Greville) Sonder, K. angusta (Harvey) and K. pectinella (Harvey) Falkenberg, and the South African K. natalensis J.Agardh. Phoographs in AD of the holotype specimen of Kuetzingia pectinella indicate that it is an earlier taxonomic synonym of Enantiocladia robinsonii and is thus the type species of the genus Plectrophora Wilson et Kraft. Kuetzingia natalensis is also transferred to Plectrophora, leaving Kuetzingia as an Australian-endemic genus of two species. A rare tropical-Atlantic species previously credited to Protokuetzingia, P. schottii Taylor, is provisionally transferred to Enantiocladia because the number of its pericentral cells and the position of its procarps conform to that of the Caribbean type species of Enantiocladia, E. duperreyi (C.Agardh) Falkenberg. This transfer leaves Protokuetzingia monotypic and also an Australian-endemic genus. A review of the genera of the Amansieae is given and conclusions are drawn as to the generic criteria most likely to be important within the tribe.

Taxonomic observations on Hypoglossum (Delesseriaceae, Rhodophyta) in the Indian Ocean and Malayan region, including the description of two new species

Two new species of the genus Hypoglossum Kützing (Delesseriaceae, Rhodophyta) are described: H. androlamellare sp. nov. from Zanzibar Island, Tanzania, and H. annae sp. nov. from the Malay Archipelago. The former is the first species of Hypoglossum to be reported from Tanzania and is distinguished by a combination of its overall habit, the chevron-like arrangement of the spermatangial sori, and the non-participation of lateral pericentral cells in sporangium formation within the tetrasporangia sori. The latter species is based on the material identified by Weber-van Bosse as “ Hypoglossum spathulatum Kützing” ( Kützing, 1849; 1869, as Delesseria spathulata Sonder), which has been recognized as having nothing to do with the present taxonomic placement of that species, Apoglossum spathulatum (Sonder) Womersley et Shepley. H. annae is distinguished by the restriction of its reproductive structures to relatively small final-order, or penultimate-order, bladelets. Hypoglossum simulans M.J. Wynne, I.R. Price et D.L. Ballantine is newly reported for Zanzibar.

Morphology of Chondrophycus undulata and C. parvipapillata and its implications for the taxonomy of the Laurencia (Ceramiales, Rhodophyta) complex

Laurencia Lamouroux subgenus Chondrophycus Tokida et Saito was recently raised to generic status as Chondrophycus (Tokida et Saito) Garbary et Harper (Ceramiales, Rhodophyta). The previously unknown morphology and anatomy of two Chondrophycus species, C. undulata (Yamada) Garbary et Harper and C. parvipapillata (C.K. Tseng) Garbary et Harper, were studied in specimens from Korea, Japan and Hawaii. These species share some features, such as a strongly compressed thallus, vegetative axes with two pericentral cells, tetrasporangial production from pericentral cells and spermatangial development of the trichoblast type. However, they differ from each other in the position of the first pericentral cell relative to the trichoblast in axial segments and in the position of the tetrasporangial pericentral cell. In C. undulata, the first pericentral cell is always produced at one side of the basal cell of a trichoblast, whereas in C. parvipapillata it is formed underneath this cell. While tetrasporangia in C. undulata are produced only from three (occasionally four) additional pericentral cells, in C. parvipapillata they are formed by the existing second pericentral cell and two (occasionally three) additional pericentral cells, so the resulting tetrasporangial axial segment has only one sterile pericentral cell rather than two as in C. undulata. C. undulata produces spermatangial branches from two laterals on the suprabasal cell of trichoblasts but one of the two remains partly sterile, whereas in C. parvipapillata a spermatangial branch develops from only one of the two laterals. These two species also differ distinctly from each other in some vegetative features, such as presence or absence of (1) secondary pit connections between epidermal cells, (2) a palisade structure of epidermal cells with conical projections and (3) corps en cerise. The taxonomic implications of these vegetative and reproductive features of Chondrophycus and those of other genera of the Laurencia complex necessitate changes to the generic delineations of Osmundea Stackhouse, Laurencia and Chondrophycus. The required new combinations in Chondrophycus are made, mainly for species from the western Pacific. An infrageneric classification scheme is also proposed for Chondrophycus including Kangjaewonia subgen. nov., Palisada (Yamada) subgen. stat. nov., Yuzurua subgen. nov. and Parvipapillatae sect. nov.

Neosiphonia flavimarina gen. et sp. nov. with a taxonomic reassessment of the genus Polysiphonia (Rhodomelaceae, Rhodophyta)

SUMMARY Vegetative and reproductive development of Neosiphonia flavimarina gen. et sp. nov. (Rhodomelaceae, Ceramiales) from Bangpo on the western coast of Korea was investigated. This species is superficially similar to Polysiphonia, but differs distinctly from the latter in vegetative and reproductive structures. The plants attach by a solid disk composed of a dense cluster of rhizoids cut off from the pericentral cell wall, and bear erect indeterminate branches producing the lateral-branch initials from successive segments in a spiral arrangement. The procarps have a three-celled carpo-gonial branch. Spermatangial branches are formed on a primary branch of the trichoblasts, terminating in a single or occasionally two large, sterile cells. Tetra-sporangia are produced from the second pericentral cell adjacent to the trichoblast basal cell on indeterminate branches, and arranged spirally. Comparing several taxonomic characters among related genera, Neosiphonia occupies an independent phylogenetic position from Polysiphonia and leads to the conclusion that the genus may have a strong link with Fernandosiphonia which has a unilateral branching system. Relevant nomenclatural changes for several Polysiphonia species are also proposed.

Organ blood flow after partial hepatectomy in rats: modification by endotoxin-neutralizing bactericidal/permeability-increasing protein (rBPI 23)

Background/Aim: Both maintenance of adequate perfusion and regeneration of the remnant liver are important in the recovery of liver function after partial hepatectomy. In previous experiments, we have shown that profound hypotension and liver injury can be attenuated by neutralizing endotoxins. The relative contribution of endotoxemia to changes in liver blood flow and blood flow to other major organs after partial hepatectomy is not known. The aim of this study was to examine the effect of endotoxin neutralization on individual organ blood flows including hepatic artery and splanchnic blood flow after experimental partial hepatectomy and its relation to liver cell proliferation. Methods: Male Wistar rats underwent either two-thirds partial hepatectomy or sham operation. Treatment consisted of continuous infusion of recombinant N-terminal bactericidal/permeability-increasing protein (rBPI 23) or control protein. At 4 h after surgery, organ blood flows were measured using the radiolabeled microsphere technique, and at 24 h, proliferation index in liver tissue was calculated. Results: After partial hepatectomy, blood flows to virtually all organs were significantly lower as compared to values obtained in sham-operated rats. rBPI 23 greatly improved hepatic artery flow ( p<0.001) but not portal venous flow. These effects of rBPI 23 on liver flow preceded an equally enhanced liver cell proliferation ( p<0.01). Endotoxin neutralization led to significantly higher flows to some but not all splanchnic organs. Lung perfusion was significantly improved by rBPI 23. Conclusions: Neutralization of endogenous endotoxins improves liver blood flow after partial hepatectomy and also periportal and pericentral liver cell proliferation. This proliferation effect may result from an increased hepatic artery flow. Lung, colon, spleen and pancreas flow but not kidney flow was greatly enhanced by rBPI 23.

Vanvoorstia incipiens sp. nov. (Delesseriaceae, Rhodophyta) from Tanzania, East Africa

Vanvoorstia incipiens DeClerk, M.J. Wynne et Coppejans sp. nov. (Delesseriaceae, Rhodophyta), a large, bushy alga of narrow axes, distinguishable from other species in the genus by its nonplanar habit and its minimal anastomoses, is described from Pongwe (6°02′S, 39°24′E), east coast of Zanzibar Island, Tanzania. The only anastomoses are those made by the final-order bladelets with adjacent penultimate-order blades, and even these occur only occasionally. The new species is also characterized by its overall habit, the narrow width of its blades, and their slight, noncontinuous cortication. Branches bearing tetrasporangia do not anastomose. The sequence of pericentral cell formation has been determined to involve the adaxial pericentral cell being formed first, followed by the pair of lateral pericentral cells, and then by the abaxial pericentral cell. This observation is discussed in reference to previous reports on species in the genus.

Osmundea maggsiana sp. nov. (Ceramiales, Rhodophyta) from the Mediterranean Sea

Osmundea maggsiana Serio, Cormaci et G. Furnari sp. nov. (Ceramjales, Rhodophyta) is described from the Mediterranean Sea. Thalli are terete, rigid in texture, and irregularly ramified and have as many as three orders of branching. Branches and branchlets are irregularly alternate to spirally (seldom suboppositely) arranged. Epidermal cells do not protrude at the ends of branchlets and have no secondary pit connections; in transverse section they are radially elongate and palisadelike. Vegetative axial segments have two pericentral cells. Tetrasporangia, produced from epidermal cells, are cut off laterally from the mother cells. The two cover cells are aligned parallel to the stichidial axis in surface view. Male gametophytes have reproductive structures of the ‘filament’ type. Spermatangial branches are simple, terminating in one or two (rarely three) spherical sterile cells and are inserted in cuplike depressions located at the bifurcation of branchlets. The new species resembles Osmundea hybrida (A.P. de Candolle) Nam in having a cylindrical thallus and cuplike spermatangial receptacles. However, O. hybrida differs from O. maggsiana in having epidermal cells that appear in transverse section to be of the nonpalisade type, in the cartilaginous to fleshy texture, in having a slightly compressed main axis and branchlets, and in having predominantly distichously arranged branches. Anatomical and reproductive characters of the new species are compared with those of other species of Osmundea.

Localization of NADPHd-exhibiting neurons in the spinal cord of the rabbit.

Segmental and laminar distributions of nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd)-exhibiting neurons were examined in the rabbit spinal cord by using horizontal, sagittal, and transverse sections. A large number of NADPHd-positive neurons in the spinal cord of rabbit appeared to fall into six categories (N1-N6), but others could not be classified. Major cell groups of NADPHd-exhibiting neurons were identified in the superficial dorsal horn and around the central canal at all spinal levels and in the intermediolateral cell column at thoracic and upper lumbar levels. NADPHd-exhibiting neurons of the pericentral region were divided into a thin subependymal cell column containing longitudinally arranged, small bipolar neurons with processes penetrating deeply into the intermediolateral cell column and/or running rostrocaudally in the subependymal layer. The second pericentral cell column located more laterally in lamina X contains large, intensely stained NADPHd-exhibiting neurons with long dendrites radiating in the transverse plane. In the pericentral region (lamina X), close association of NADPHd-exhibiting somata and fibers and mostly longitudinally oriented blood vessels were detected. Neurons of the sacral parasympathetic nucleus, seen in segments S1-S3, exhibited prominent NADPHd cellular staining accompanied by heavily stained fibers extending from Lissauer's tract through lamina I along the lateral edge of the dorsal horn to lamina V. A massive dorsal gray commissure, highly positive in NADPHd staining, was found in segments S1-S3. Scattered positive cells were also found in the deeper dorsal horn, ventral horn, and white matter. Fiberlike NADPHd staining was found in the superficial dorsal horn and pericentral region in all the segments studied. Dense, punctate, nonsomatic NADPHd staining was detected in the superficial dorsal horn, in the pericentral region all along the rostrocaudal axis, and in the nucleus phrenicus (segments C4-C5), nucleus dorsalis (segments Th2-L2), Onuf's nucleus (segments S1-S3), and the dorsal part of the dorsal gray commissure (S1-S3).

Pseudogrinnellia barrattiae gen. et sp. nov., a New Member of the Red Algal Family Delesseriacea from the Sultanate of Oman

Pseudogrinnellia barrattiae M. J. Wynne gen. et sp. nov., a monotypic genus of Delesseriaceae (Rhodophyta), is described from the Sultanate of Oman. The new genus is based on three tetrasporangial specimens collected from the southern part of Oman on the northern Arabian Sea during the monsoon season. Pseudogrinnellia is assigned to the tribe Delesserieae and is distinguished by the following combination of characteristics: a monostromatic, weakly costate blade, simple or bearing one order of small bladelets from the midrib; faint development of lateral veins in basal portion of blade; lateral pericentral cells undergoing transverse division; numerous small tetrasporangial sori randomly scattered over primary blade surface; and the production of microscopic bladelets from the soral regions.

Hypoglossum fujianensis sp. nov. (Delesseriaceae, Rhodophyta) from Fujian Coast, China

Hypoglossum fujianensis sp. nov. is an epiphytic alga in the intertidal zone. Plants are light red, 0.9–2 cm high. Margin of branches gives rise to uniseriate hair-like rhizoids, formed outward from the fusion of the second-and third-order cells. Blades are single layered (except the midrib) and uncorticated. Tetrasporangial sori are formed on the middle part of blades. The globular tetrasporangia are developed from lateral pericentral cells.

Ululania stellata gen. et sp. nov. (Rhodomelaceae), a new genus and species of parasitic red algae from Hawaii

Ululania stellata Apt et Schlech gen. et sp. nov. infects two species of Acanthophora (Rhodomelaceae, Ceramiales) in Hawaii. Thalli are minute (to 3 mm in diameter), colorless pustules consisting of a central, relatively undifferentiated mass of radially elongated cells that bears numerous short (to 1 mm in length), radiating, unbranched fertile axes. Trichoblasts occur on dioecious male and female gametophytes, but not on tetrasporophytes. Procarps develop on the suprabasal cells of trichoblasts and consist of a four-celled carpogonial branch and a single-celled sterile lateral borne on the supporting cell. Trichoblasts on male gametophytes form shallowly lobed to obcordate leaflets on which the surface and most marginal cells bear spermatangia, a consolidated margin of sterile cells being absent. Tetrahedrally divided tetrasporangia occur in whorls of up to seven per tier of pericentral cells within stichidioid branchlets. Features of the vegetative axes, procarp, spermatangial trichoblasts, and tetrasporangial stichidia show the new genus to be an adelphoparasite belonging to the Chondrieae.

Reduced nicotinamide adenine dinucleotide phosphate diaphorase in the spinal cord of dogs

The distribution of somatic, fibre-like and punctate, non-somatic reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase activity was examined in dog spinal cord using horizontal, sagittal and transverse sections. The morphological features of NADPH diaphorase exhibiting neurons divided into six different neuronal types (N1–N6) were described and their laminar distribution specified. Major cell groups were identified in the superficial dorsal horn and around the central canal at all spinal levels, and in the intermediolateral cell column at thoracic level. NADPH diaphorase exhibiting neurons of the pericentral region were distributed in a thin subependymal cell column containing longitudinally-arranged small bipolar neurons with processes penetrating deeply into the intermediolateral cell column and/or running rostrocaudally in the subependymal layer. The second pericentral cell column located more laterally in lamina X contains large, intensely-stained NADPH diaphorase exhibiting neurons with long dendrites radiating in the transverse plane. Neurons of the sacral parasympathetic nucleus seen in segments S 1–S 3 exhibited prominent NADPH diaphorase activity accompanied by heavily-stained fibres extending from Lissauer's tract through lamina I along the lateral edge of the dorsal horn to lamina V. A massive dorsal gray commissure, with high NADPH diaphorase activity, was found in segments S 1–S 3. At the same segmental level a prominent group of moderately-stained motoneurons was detected in the dorsolateral portion of the anterior horn. Fibre-like NADPH diaphorase activity was found in the superficial dorsal horn and pericentral region in all segments studied. Punctate, non-somatic NADPH diaphorase activity was detected in the superficial dorsal horn, in the pericentral region all along the rostrocaudal axis and in the nucleus phrenicus (segments C 4–C 5), nucleus dorsalis (segments Th 2–L 2), nucleus Y (segments S 1–S 3), and the dorsal part of the dorsal gray commissure (S 1–S 3). A schematic diagram documenting the segmental and laminar distribution of NADPH diaphorase activity is given.

Polysiphonia perforans sp. nova (Ceramiales, Rhodophyta) from the Mediterranean Sea

ABSTRACT A new species of the genus Polysiphonia from the Mediterranean Sea is described. It is an ecorticate species, with 4 pericentral cells, showing prostrate axes from which erect axes arise. Rhizoids are formed by pericentral cells in a median position remaining in open connection with them. Erect axes are straight, simple throughout or pseudodichotomous at the base then simple or with one (rarely two-three) orders of branching; trichoblasts and scar cells not observed. Only tetrasporangial plants were found. They show ellipsoid tetrasporangia borne in short straight series, often interrupted by sterile segments. The new species is also characterized by a peculiar habit consisting of prostrate axes, adhering to lower faces of Peyssonnelia spp. by means of rhizoids growing upward, from which erect upright axes perforating thalli of the supporting species arise. A comparison with the related species of Polysiphonia was also carried out.

Apical control of growth in a filamentous red alga (Ceramiaceae, Rhodophyta)

The undescribed ceramiacean red alga used in this work is closely related to Ceramium . The alga is pseudodichotomously branched with alternate axes being dominant. Removal of the apical tip from the primary indeterminate axis increased the production of adventitious branches from pericentral cells behind the apex. This effect was not reversed with the addition of exogenous IAA to the growth medium in a concentration range of 10 − 9 M to 10 − 4 M. Removal of the apical tip from the subordinate axis did not influence adventitious branch production.

Difference between periportal and pericentral Kupffer cells in lipopolysaccharide uptake in rats.

To reveal the difference in the ability of Kupffer cells in the periportal and pericentral regions of the liver to uptake lipopolysaccharides (LPS) injected into the portal vein. Male Wistar rats were divided into two groups: normal control group (n = 6) and GdCl3-treated group (n = 8). Sixteen hours before the experiment, rats in the GdCl3-treated group were injected with GdCl3 via the tail vein to eliminate Kupffer cell function specifically in the periportal region. LPS at a dose of 20 μg/100 g body weight was injected into rats of both groups via the portal vein. Zero, 2, 5, 10, 30, and 60 min after LPS injection, liver samples were obtained and the distribution of LPS in Kupffer cells was observed by immunofluorescence imaging of monoclonal antibody-specific LPS staining using a confocal laser scanning microscope. In the normal control group, positive reactions to LPS were found in Kupffer cells in the periportal region with the peak at two minutes after LPS injection. Kupffer cells in the pericentral region showed the peak at five minutes after LPS injection, but its fluorescent intensity to LPS at the peak time in the cytoplasm was significantly lower than that of Kupffer cells in the pericentral region. In the GdCl3-treated group, Kupffer cells in the pericentral region showed the peak at two minutes following LPS injection, and the LPS fluorescent intensity showed no significant difference from that of the normal control rats at the peak point. No significant changes of LPS fluorescent intensities were found in Kupffer cells in the periportal region at various time points following LPS injection in GdCl3-treated rats. Kupffer cells in the periportal and pericentral regions showed differences in LPS uptake via the portal vein.

In situ measurement of glutamate concentrations in the periportal, intermediate, and pericentral zones of rat liver.

We developed a quantitative histochemical assay for measurement of local glutamate concentrations in cryostat sections of rat liver. Deamination of glutamate by glutamate dehydrogenase (GDH) was coupled to the production of formazan and formazan precipitation was used for colorimetric visualization. The method was tested and validated with gelatin model sections with known glutamate concentrations. Calibration graphs showed linear relationships with high correlation coefficients (> 96%) between glutamate concentrations or section thickness and absorbance values. The method was reproducible, with a constant percentage of 60 +/- 5% of glutamate being converted in gelatin model sections containing glutamate concentrations of 2 mM and higher. Glutamate concentrations were estimated in periportal, intermediate, and pericentral zones of liver lobules that contain low, intermediate, and high GDH activity, respectively. In fed adult male rat livers, periportal zones contained the highest concentrations of glutamate (approximately 14 mM) and intermediate and pericentral zones approximately 13 and 9 mM, respectively. On starvation, glutamate concentrations increased only in the small rim of pericentral cells that express glutamine synthetase, to approximately 15 mM. In livers of fetal and newborn rats, glutamate was homogeneously distributed, with a concentration of approximately 5 mM. In suckling rat liver, distribution of glutamate was still homogeneous but the concentration was increased to approximately 8 mM. These glutamate distribution patterns were in agreement with those detected immunohistochemically.