bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterisation of glycoconjugate sugar residues in the vomeronasal organ of the armadillo Chaetophractus villosus (Mammalia, xenarthra)
Authors: CARMANCHAHI P. D. , FERRARI C. C. , ALDANA MARCOS H. J. , AFFANNI J. M. , SONEZ C. A. , PAZ D. A.
Published: March 2003

Conventional carbohydrate histochemistry and the binding patterns of 21 lectins were analysed to characterise the glycoconjugate content in the components of the vomeronasal organ of the armadillo Chaetophractus villosus. The mucomicrovillous complex of the sensory epithelium bound most of the lectins studied. No reaction was observed with Con A, PSA, S‐Con A and SBA, and the sustentacular cells were stained with UEA‐I, DSL, LEL, STL and Con A. The vomeronasal receptor neurons were labelled with S‐WGA, WGA, PNA, UEA‐I, STL, Con A, S‐Con A, ECL and RCA120. The basal cell layer reacted with S‐WGA, WGA, LCA, UEA‐I, DSL, LEL, STL, Con A, JAC and VVA. The nonsensory epithelium exhibited a differential staining in relation to the different components. The mucociliary complex stained with ECL, DBA, JAC, RCA120, STL, LCA, PHA‐E, PHA‐L, LEL, BSL‐I and VVA. However, SJA and UEA‐I stained the mucus complex lining a subpopulation of columnar cells. The cytoplasm and cell membranes of columnar cells was labelled with DBA, DSL and LCA. The apical region of these cells exhibited moderate reactivity with LEL and SJA. None of the lectins bound specifically to secretory granules of the nonsecretory cells. Basal cells of the nonsensory epithelium were labelled with DSL, LEL, LCA, BSL‐I and STL. The vomeronasal glands showed a positive reaction with WGA, DSL, LEL, LCA, DBA, PNA, RCA120 and SBA. Subpopulations of acinar cells were observed with ECL, S‐WGA, Con A, S‐Con A and DBA. PNA and RCA120 stained the cells lining the glandular ducts. In comparison with previous results obtained in the olfactory mucosa of the same group of armadillos, the carbohydrate composition of the vomeronasal organ sensory epithelium differed from the olfactory sensory epithelium. This is probably related to the different nature of molecules involved in the perireceptor processes.
A comparative study of mammalian tracheal mucous glands
Authors: CHOI H. K. , FINKBEINER W. E. , WIDDICOMBE J. H.
Published: March 2003

We have compared the distribution, numbers and volume of mucous glands in the tracheas of 11 mammalian species. No glands were present in the rabbit. The mouse only contained glands at the border between the trachea and larynx. In the rat, glands were commonest in the cephalad third of the trachea, but on average were much scarcer than in the larger species. Between species, there was a significant correlation between airway diameter and gland volume per unit surface area, suggesting that the rate of deposition of inhaled particles may increase in large airways. In the ventral portion of the trachea of about half the species, the glands were concentrated between the cartilaginous rings; in others they were evenly distributed over and between the rings. In most species in which the trachealis muscle attached to the internal surface of the cartilaginous rings, the glands were external to the muscle. In all species in which the muscle attached to the external surface of the cartilaginous rings, the glands were internal to the muscle. In the ox, goat, dog and sheep, the volume of glands per unit tracheal surface area was markedly greater in the ventral than the dorsal aspect of the trachea. The reverse was true of the pig. In humans, gland density in the 2 regions was similar. The frequency of gland openings was determined in the ox, goat, pig, dog and sheep tracheas, and ranged from 0.3 per mm2 in the dorsal portion of the sheep trachea to 1.5 per mm2 in the ventral portion of the ox trachea. For these 5 species, the volume of gland acini per unit luminal surface area varied linearly with the numbers of gland openings, with the volume of individual glands being constant at ∼ 120 nl.
The structural organisation of sperm head components of the wombat and koala (suborder: Vombatiformes): an enigma amongst marsupials
Authors: BREED WILLIAM G. , LEIGH CHRISTOPHER M. , RICCI MARIO
Published: March 2003

The sperm head structural organisation of the koala and hairy‐nosed wombat, and the effects of varying concentrations of the ionic detergent, Triton X‐100, on its component parts, were determined by electron microscopy. Although alike in form between the 2 species, the sperm nucleus of the former, but not the latter, had nuclear vacuoles and appeared to be more easily dispersed by the Triton X‐100. The structure of the acrosome of the spermatozoon was similar between the 2 species and, in both, previously undescribed thin posterior and lateral segments were found to be present. It is suggested that this thin segment may facilitate sperm‐zona and/or sperm‐oolemma binding and fusion.
Professor Edward George Gray, FRS (1924–1999)
Authors: GUILLERY R. W.
Published: March 2003

Professor George Gray, who died in August 1999, had a notable career as a pioneer electron microscopist of neural tissues. His name is still attached to synapses, which can be classified as Gray type 1 (symmetric) or type 2 (asymmetric), and in addition he made a number of other profound contributions to our knowledge of synaptic structures.

He started his academic career late, having worked before the second World War as a bank clerk, and then serving in the Navy, patrolling for U‐boats in the North Sea and Atlantic for 4 years during the latter part of the war. He had an early interest in zoology, particularly in marine biology and microscopy and when he left the Navy he took the opportunity to work for a degree in Zoology at the University of Wales in Aberystwyth. A first class honours degree was followed by a PhD on melanophores in teleosts. It was fortunate that the external examiner for the thesis was J. Z. Young, who was impressed by the work and by George, and who invited George to work as his assistant in the preparation of The Life of the Mammals in the Anatomy Department at University College London.
Immunohistochemical identification of cells expressing ATP‐gated cation channels (P2X receptors) in the adult rat thyroid
Authors: GLASS RAINER , BURNSTOCK GEOFFREY
Published: March 2003

We carried out immunohistochemistry and western blotting of fresh frozen sections and crude extracts from adult rat thyroids. The histochemical and immunoblotting studies were performed with P2X receptor antibodies from 2 different sources. P2X‐immunopositive cells were identified by fluorescence double labelling and confocal microscopy. Results of the western blotting experiments showed double bands of approximately 70 kDa and 140 kDa for all 7 P2X receptor subtypes with both sets of antibodies. Histochemical stains with antibodies from both sources also gave essentially identical results. P2X1, P2X2 and P2X6 receptors were detected exclusively in vascular smooth muscle; P2X5 and P2X7 receptors were also present on vascular smooth muscle. Endothelial cells stained for P2X3, P2X4 and P2X7 receptors. Thyroid follicular cells displayed immunoreactivity for P2X3, P2X4 and P2X5 receptors. No immunostaining for P2X receptors was observed on C‐cells. Possible roles for the broad expression of P2X receptor subtypes in the rat thyroid are discussed.
Origin of the vertebrate inner ear: evolution and induction of the otic placode
Authors: STREIT ANDREA
Published: March 2003

abstract

The vertebrate inner ear forms a highly complex sensory structure responsible for the detection of sound and balance. Some new aspects on the evolutionary and developmental origin of the inner ear are summarised here. Recent molecular data have challenged the longstanding view that special sense organs such as the inner ear have evolved with the appearance of vertebrates. In addition, it has remained unclear whether the ear originally arose through a modification of the amphibian mechanosensory lateral line system or whether both evolved independently. A comparison of the developmental mechanisms giving rise to both sensory systems in different species should help to clarify some of these controversies. During embryonic development, the inner ear arises from a simple epithelium adjacent to the hindbrain, the otic placode, that is specified through inductive interactions with surrounding tissues. This review summarises the embryological evidence showing that the induction of the otic placode is a multistep process which requires sequential interaction of different tissues with the future otic ectoderm and the recent progress that has been made to identify some of the molecular players involved. Finally, the hypothesis is discussed that induction of all sensory placodes initially shares a common molecular pathway, which may have been responsible to generate an ‘ancestral placode’ during evolution.
Evaluation of three‐dimensional glenoid structure using MRI
Authors: INUI HIROAKI , SUGAMOTO KAZUOMI , MIYAMOTO TAKASHI , MACHIDA AKITOSHI , HASHIMOTO JUN , NOBUHARA KATSUYA
Published: March 2003

The tilting angle and the shape of the glenoid cavity are considered to relate closely to shoulder stability. They are also important when planning arthroplasty and developing new designs. This study examines the glenoid cavity using 3‐dimensional MRI. Forty volunteers (20 men, 20 women; average age 21.4; range 18–35 y) were enrolled in the study. The tilting angles of the glenoid bone were measured in 5 consecutive axial planes perpendicular to the glenoidal long axis. Cross sections were divided into 3 types (concave, flat, convex) according to the shape on each plane.

The average tilting angles for the 5 planes from the bottom to the top were 3.3±4.1, 1.4±3.8, −0.6±1.9, −1.4±3.3, and −6.2±3.3 degrees anteriorly, indicating that the 3‐dimensional bony structure of the glenoid was twisted anteriorly to posteriorly. Images on the bottom plane consisted of 82.5% concave type, 15% flat type and 2.5% convex type, while only 3 cases (7.5%) showed concave at the top plane. The shape of the glenoid cavity is thought to be conducive to glenohumeral motion and stability.
The ileal flange: an anatomical landmark
Authors: SINGH B. , MOODLEY J. , SATYAPAL K. S.
Published: March 2003

The abdominal surgeon is largely unappreciative of the peritoneal reflections of the ileocaecal region. This is not surprising since the literature on this subject is sparse. The available descriptions in standard texts (Hollinshead, 1971; McMinn, 1994; Williams et al. 1995) outline the appendicular mesentery as developing from the lowest aspect of the ileal mesentery. The inferior ileocaecal recess develops between the mesentery of the appendix and the ileocaecal fold; the superior ileocaecal recess develops between the ileal mesentery and the vascular fold of the caecum. The clinical significance of these recesses is minimal as they neither predispose to entrapment of bowel nor serve as useful landmarks. In this context, the peritoneal flange on the anti‐mesenteric aspect of the terminal ileum warrants consideration (Fig. 1). This extension of the ileocaecal fold along a variable distance on the antimesenteric terminal ileum is largely underappreciated as it may hold value as a useful landmark to the abdominal surgeon.
Variant palmaris profundus enclosed by an unusual loop of the median nerve
Authors: CHOU HSIU‐CHU , JENG HELLEN , KO TSUI‐LING , PAI MAN‐HUI , CHANG CHIU‐YUN , WU CHING‐HSIANG
Published: March 2003

According to the usual description in most anatomy texts, the median nerve in the forearm passes between the 2 heads of pronator teres. It continues distally between flexor digitorum superficialis and profundus almost to the retinaculum. Muscular branches leave the nerve near the elbow and supply all superficial muscles of the anterior part of the forearm except flexor carpi ulnaris. Many variations of the median nerve in the forearm have been reported (Urban & Krosman, 1992). The palmaris profundus is also a rare anomaly of the forearm (Dyreby & Engber, 1982). It originates from the radial side of the common flexor tendon in the proximal forearm and inserts into the undersurface of the palmar aponeurosis. The origin of palmaris profundus may be close to the median nerve and its branches, and may be involved in compressive neuropathy of the anterior interosseous nerve. Its tendon crossing through the carpal canal has been implicated in the carpal tunnel syndrome (reviewed by Lahey & Aulicino, 1986). In some cases, palmaris profundus was found enclosed in a common fascial sheath with the median nerve (Stark, 1992; Sahinoglu et al. 1994). To indicate its close association with the median nerve, the palmaris profundus was also named ‘musculus comitans nervi mediani’ (Sahinoglu et al. 1994). This article reports an unusual loop of the median nerve encircling an anomalous palmaris profundus in the forearm, which, to the best of our knowledge, has not been previously described.
The three‐dimensional microanatomy of the rabbit and human cornea. A chemical and mechanical microdissection‐SEM approach
Authors: OJEDA JOSÉ L. , VENTOSA JUAN A. , PIEDRA SONSOLES
Published: March 2003

The three‐dimensional (3D) microanatomy of the cornea is the major determinant of its optical and mechanical properties. Scanning electron microscopy (SEM) is the most commonly used method to obtain information on the overall 3D microanatomy of organs. However, SEM has not been successful in revealing the 3D microanatomy of the cornea, because the interior of the cornea is too compact to be explored by the electron beam. In this study, the 3D organisation of the cells and extracellular materials of human and rabbit corneas was examined after exposure by HCl and NaOH digestion, and by microdissection by the adhesive tape method. In the cornea of both species, all epithelial cells exhibited microplicae regardless of their location. This raises doubts about the tear film‐holding role assigned to the microplicae of the superficial cells. Human and rabbit corneas differed in the collagen fibre patterns of the epithelial basement membranes. The 3D organisation of the stromal lamellae was similar in both species. In humans and rabbits, the keratocytes showed similar 3D features. However, the surface of human keratocytes located near Descemet's membrane exhibited small fenestrations that were not present in the rabbit keratocytes. The pattern of keratocyte innervation by the stromal neural plexus and 3D keratocyte microanatomy confirms that keratocytes form a large intercommunicating network within the corneal stroma. Two morphologically discrete subpopulations of keratocytes located at different stromal levels were identified in both human and rabbit corneas, suggesting that keratocytes are not functionally homogeneous. In addition, the density of the stromal neural plexus appeared to be greater in rabbits than in humans. Clear differences between human and rabbit corneas were observed in the collagen arrangement in Descemet's membrane, which may reflect their different biomechanical requirements.
Annexin 1: a new paracrine agent secreted by a novel mechanism
Authors: Morris J. F. , Christian H. C. , Epton M. J. , Chapman L. P.
Published: March 2003

Glucocorticoid feedback on the pituitary inhibits the secretion of many pituitary hormones, including ACTH, growth hormone and prolactin. This inhibition involves not only the relatively slow genomic inhibition of hormone synthesis via classical intracellular glucocorticoid receptors but also much a more rapid inhibition which is independent of transcription. Annexin 1 is a protein produced by the folliculo‐stellate cells of the pituitary. Antibodies and antisense to annexin 1 block this more rapid inhibition. We now show that, despite the fact that annexin 1 lacks a signal sequence and is not packaged in secretory granules, glucocorticoids cause the externalisation of annexin 1 to a membrane‐associated pool (calcium‐dependent and bound to phospholipid) from which annexin 1 can be released. Annexin 1 is externalised at specific points on the membrane of a folliculo‐stellate cell line; these may correspond to the points at which folliculo‐stellate cells are attached to endocrine cells in situ. The externalisation of annexin 1 can be blocked by the sulphonylurea glyburide, an inhibitor of ATP‐binding cassette (ABC) transporters which can translocate other large proteins across membranes. ABC1 transporter protein and mRNA are both present in pituitary folliculo‐stellate cells. Annexin 1 is not restricted to the pituitary, but is widely distributed in macrophages and other tissues in which it is involved in the suppression of inflammation. It therefore appears that paracrine regulation can be exerted by a protein that is not packed in secretory vesicles and which is externalised from cells by a mechanism very different to that which controls the secretion of most peptides and proteins.
Modulation of angiogenesis is effective in a model of rheumatoid arthritis
Authors: Afuwape A. O. , Paleolog E. M.
Published: March 2003

A feature of rheumatoid arthritis (RA) is prominent hyperplasia of the synovium, which results in an increased distance between the invasive pannus and the existing synovial vasculature. Concomitantly the hyperplastic tissue imposes an augmented metabolic demand on the pre‐existing vasculature. As a consequence the synovium in RA becomes hypoxic, resulting in an increased rate of formation of new blood vessels, to supply nutrients and oxygen. Targeting the vasculature in RA is a potential therapeutic approach in RA. VEGF, a key vascular permeability and angiogenic factor, is expressed in RA. In this study we utilised adenovirus expressing the secreted form of the extracellular domain of the Flt‐1 VEGF receptor (sFlt‐1) to inhibit VEGF in the collagen‐induced arthritis (CIA) model, to determine whether blocking the effects of vegf might be an effective treatment for RA.

AdvsFlt‐1, administered intravenously on the first day of arthritis, significantly suppressed CIA. For example, on d 6 of arthritis the mean increase in paw thickness, which reflects oedema, for untreated and null adenovirus‐treated animals was 0.23 ± 0.05 mm and 0.38 ± 0.08, respectively, compared to 0.07 ± 0.05 for AdvsFlt‐1‐treated mice (P < 0.001 vs. Adv0‐treated and untreated mice by 2‐way anova). Western blot analyses revealed the presence of a 100‐kDa band, corresponding to human sFlt‐1, in liver extracts from arthritic mice infected with AdvsFlt‐1 at 24 h but not 72 h after infection. This band was absent in liver extracts from Adv0‐infected mice and all synovial extracts. Measurement of protein levels by ELISA demonstrated the presence of sFlt‐1 in liver, synovium and serum, although levels declined by 72 h post infection. These data suggest efficient but transient expression of sFlt‐1. Sera from adenovirus infected mice were found to contain antiviral antibodies and additionally, sera from AdvsFlt‐1‐infected but not Adv0‐infected mice recognised human recombinant sFlt‐1.

These observations demonstrate that adenoviral mediated delivery of human sFlt‐1 leads to transient gene expression and suppression of CIA. This effect is reduced later in the course of disease due to the expression of antiadenovirus as well as antisFlt‐1 antibodies. Future studies will assess the effect of combination treatment, using AdvsFlt‐1 together with anti‐TNF(antibody, to prolong the beneficial effects of VEGF blockade. These results suggest that blocking the pro‐angiogenic and permeability action of VEGF may be beneficial for treatment of RA.
The aquaporin‐1 water channel protein is abnormally expressed in oedematous human brain tumours
Authors: Papadopoulos M. C. , Saadoun S. , Krishna S. , Bell B. A. , Davies D. C.
Published: March 2003

The aquaporins (AQPs) comprise a family of at least 10 highly conserved water channel proteins. Of these only AQP1 and AQP4 are significantly expressed in the brain. In normal brain AQP1 is expressed by the choroid plexus, whereas AQP4 is expressed by astrocyte end‐feet surrounding brain microvessels and forming the glial limiting membrane under the pia mater and ependyma. In order to begin to investigate whether AQP1 is involved in brain water homeostasis, the expression of AQP1 was compared in normal human brain and in human brain tumours where brain water homeostasis is disrupted. Formalin fixed, paraffin embedded samples of morphologically normal human brain (n = 5), low‐grade (Daumas‐Duport I or II) astrocytomas (n = 5), high‐grade (Daumas‐Duport III or IV) astrocytomas (n = 5) and adenocarcinoma metastases to the brain (n = 5) were obtained from patients who underwent surgery at Atkinson Morley’s Hospital during 1998–9. Astrocytomas and metastatic adenocarcinomas were investigated because they are the commonest human brain tumours. Immunocytochemistry was performed using a polyclonal rabbit anti‐AQP1 primary antibody (AB3065, Chemicon). The immunoreactivity was visualised using immunoperoxidase and diaminobenzidine. In all samples of non‐neoplastic and neoplastic brain, AQP1 immunoreactivity was found over erythrocyte cell membranes. In morphologically normal human brain AQP1 immunolabelling was occasionally observed over microvessel endothelial cells. In 4/5 low grade astrocytomas AQP1 immunolabelling was present over most microvessel endothelial cells and at the periphery of most tumour cells. In all high grade astrocytomas, dense AQP1 immunolabelling was present over most microvessel endothelial cells and both at the periphery and throughout the cytoplasm of most tumour cells. In all metastatic adenocarcinomas AQP1 immunolabelling was present over most microvessel endothelial cells. In 2/5 adenocarcinoma samples AQP1 immunoreactivity was also present in cells with the morphology of reactive astrocytes that were in close proximity to the tumour cells. The presence of AQP1 immunoreactivity in cells within human brain tumours that do not normally express AQP1 and the increasing AQP1 expression with tumour severity, suggest that AQP1 may play a role in the formation of brain tumour oedema. Since brain oedema increases the morbidity and mortality of patients with brain tumours, blocking the AQP1 water channel may provide a way to improve the prognosis of such patients.
Three‐dimensional sonographic evaluation of the fetal lumbar spinal canal
Authors: Wallny Thomas , Schild Ralf L. , Fimmers Rolf , Hansmann Manfred E.
Published: March 2003

In a prospective cross‐sectional ultrasound study the size of the fetal lumbar spinal canal was evaluated to determine reference values for the lumbar part of the vertebral canal. One hundred and sixty‐seven pregnant women undergoing routine obstetric ultrasound were studied between 16 and 41 weeks of gestation. Exclusion criteria consisted of structural fetal anomalies or growth restriction. Area and volume of the vertebral canal at L1, L3 and L5 were calculated by three‐dimensional (3D) ultrasound. Length of the lumbar spine was also determined. The size of the spinal canal and spinal length correlated well with gestational age. No gestational‐age‐dependent differences in area and volume measurements between upper and lower lumbar spine were found. The results provide an in vivo assessment of the spinal canal by 3D ultrasound over the entire gestation period.
Immunocytochemical localization of angiotensin II receptor subtypes 1 and 2 in the porcine fetal, prepubertal and postpubertal ovary
Authors: Shuttleworth Gail , Hunter Morag G. , Robinson Graham , Broughton Pipkin Fiona
Published: March 2003

There is considerable evidence for a mammalian ovarian renin–angiotensin system, which may influence ovulation, angiogenesis and steroidogenesis via the autocrine and/or paracrine actions of the biologically active product of the cascade, angiotensin II (AngII). There are two characterized AngII receptors – type 1, AT1 and type 2, AT2. We report the localization of these receptor subtypes within porcine fetal, prepubertal and postpubertal ovaries. Positive staining for AT1 and AT2 receptors was observed in egg nests in all fetal ovaries studied, as well as in a defined two‐cell layer at the ovarian periphery. In prepubertal tissue, positive AT1 and AT2 staining was localized to granulosa cells adjacent to the basement membrane of pre‐antral and antral follicles, with no staining in the thecal layer. There was immunostaining for both receptors in prepubertal oocytes and zona pellucida. In postpubertal tissue, positive AT1 and AT2 immunostaining was localized to areas of putative neovascularization, the zona pellucida and the oocyte. Further AT1 staining was located to the postpubertal antral follicle granulosa cells. The results indicate that there are higher densities of AT1 receptors than AT2 receptors in the porcine fetal, prepubertal and postpubertal ovary, and this has profound implications for the role of AngII in ovarian development.
Developmental mechanisms underlying polydactyly in the mouse mutant Doublefoot
Authors: Crick Alexandra P. , Babbs Christian , Brown Jennifer M. , Morriss‐Kay Gillian M.
Published: March 2003

The pre‐axial polydactylous mouse mutant Doublefoot has 6–9 digits per limb but lacks anteroposterior polarity (there is no biphalangeal digit 1). It differs from other polydactylous mutants in showing normal Shh expression, but polarizing activity (shown by mouse‐chick grafting experiments) and hedgehog signalling activity (shown by expression of Ptc1) are present throughout the distal mesenchyme. The Dbf mutation has not yet been identified. Here we review current understanding of this mutant, and briefly report new results indicating (1) that limb bud expansion is concomitant with ectopic Ihh expression and with extension of the posterior high cell proliferation rate into the anterior region, and (2) that the Dbf mutation is epistatic to Shh in the limb.
The effect of the slow‐to‐green mutation on cell division during leaf initiation and early leaf growth in Lolium temulentum
Authors: MOSES LYNNE , OUGHAM HELEN J. , FRANCIS DENNIS
Published: March 2003

Cell division was examined during leaf initiation in the slow‐to‐green mutant of Lolium temulentum L. to test the hypothesis that the cell cycle in the leaf primordium is a key regulator of the well characterized reduction in final leaf length in the mutant compared with that of the wild type. The cell doubling time (cdt, by colchicine method) was substantially longer in the youngest leaf primordium (YLP) of the mutant (107 h) than in the wild type (43 h) although the duration of the most rapid cell cycle (cc, by percentage labelled mitoses method) was between 18–20 h in each. As a consequence, the proportion of rapidly proliferating cells was only 20 % in the mutant compared with 47 % in the wild type. The size of the shoot apical meristem and the plastochron were similar between genotypes which indicates that the shoot meristem was largely buffered from the effects of the mutation. Mitotic cell area was also similar in the YLP of both genotypes. However, as the leaf elongated, mitotic cell area and interphase cell size were significantly larger in the mutant compared with the wild type. This change was coupled with a reduced number of cells per unit length of leaf in the mutant. The data are consistent in showing that the proportion of rapidly proliferating cells in the YLP (but not the rate of cell division) is a key parameter which influences growth of the leaf.
Effects of elevated CO2, nitrogen and phosphorus on the growth and photosynthesis of two upland perennials: Calluna vulgaris and Pteridium aquilinum
Authors: WHITEHEAD S. J. , CAPORN S. J. M. , PRESS M. C.
Published: March 2003

Bracken (Pteridium aquilinum (L.) Kuhn) and heather (Calluna vulgaris (L.) Hull) are important upland species which often grow in close proximity in the UK. The effects of factorial treatments of elevated atmospheric CO2 (539 μmol mol−1 as opposed to ambient atmospheric CO2 concentrations of 355 μmol mol−1), added N (50 kg N ha−1 as NH4NO3) and added P (20 kg P ha−1 as NaH2PO4) on the performance of these two species were studied under controlled environmental conditions using container‐grown plants. Plants grown and measured at high CO2 had higher rates of net photosynthesis than those grown and measured in ambient CO2. This increase was greater in heather than in bracken and resulted in a large stimulation of growth in the former. In bracken there was no significant change in plant size or phenology. The increase in biomass of heather in high CO2 was greatest in the absence of added nutrients and lowest when both N and P were supplied. The growth and photosynthesis of both plants responded positively to the supply of P alone or P with N (in both CO2 atmospheres), but there was little response to N alone. The implications of these findings for bracken and heather growing in the field under conditions of an elevated CO2 atmosphere and greater nutrient availability are discussed.
Costs and benefits of mycorrhizal infection in a spring ephemeral, Erythronium americanum
Authors: LAPOINTE LINE , MOLARD JULIE
Published: March 2003

summary

Spring ephemerals have evolved specific growth strategies that take advantage of the high photon fluence rates of early spring. These strategies involve a sequential growth of different organs. Erythronium americanum (Ker‐Gawl), a common spring ephemeral of northern maple forests, produces its roots in the autumn, although stems and leaves develop in the spring. Mycorrhizal infection of the root system occurs very rapidly and intensively. The fungi thus depend on carbohydrate reserves accumulated in the corm (underground reserve organ) for their growth and development through the winter. We found that the presence of mycorrhizas drastically decreases root growth during the cold period and is more costly of carbohydrate reserves than root growth alone. However, during the spring, the presence of mycorrhizas fully benefits the plant: we measured an annual growth rate of mycorrhizal plants twice that of fungicide‐treated plants which were non‐mycorrhizal. We suspect that E. americanum is highly susceptible to water stress during the growing season and might rely on its mycorrhizas for water supply to a greater extent than for nutrient supply. Nutrient uptake might occur mainly in the autumn when arbuscules are at their most abundant.
Changes in microtubule arrays in symbiotic orchid protocorms during fungal colonization and senescence
Authors: UETAKE YUKARI , FARQUHAR MELISSA L. , PETERSON R. LARRY
Published: March 2003

Microtubule arrays were studied in Spiranthes sinensis (Pers.) Ames protocorms cultured in vitro either asymbiotically or symbiotically with the fungus Ceratobasidium cornigerum (Bourdot) Rogers by localizing β‐tubulin in hand sections observed with laser scanning confocal microscopy. Cortical microtubules present in uncolonized cells disappeared when cells became colonized by the fungus. However, microtubules were observed between the hyphae forming hyphal coils (pelotons) in colonized cells. In these cells a close relationship between pelotons, microtubules and nuclei was often observed, and microtubules associated with hyphae formed a net‐like structure through the pelotons. During senescence and condensation of the pelotons, microtubules were observed surrounding the pelotons, between collapsing hyphae and as circular profiles within the collapsed hyphal masses. In cells which contained completely collapsed hyphal masses and which were not recolonized, cortical microtubules reappeared and continued from the cell periphery through the hyphal remains to the collapsed hyphal masses. Microtubules associated with hyphae seemed to be involved in the condensation of hyphal masses in the host cells. Microtubules were also observed within hyphae, except in those which were collapsing or had collapsed.
Effects of liming on the uptake of organic and inorganic nitrogen by mycorrhizal (Paxillus involutus) and non‐mycorrhizal Pinus sylvestris plants
Authors: ANDERSSON SOLBRITT , EK HANS , SÖDERSTRÖM BENGT
Published: March 2003

Seedlings of Pinus sylvestris L. were grown in Plexiglas® observation chambers in limed (CaCO33, pH 5.0 and 5.9) and untreated (pH 4.1) peat. The seedlings were either colonized by the mycorrhizal fungus Paxillus involutus (Batsch: Fr.) Fr. Or were non‐mycorrhizal. After 18 wk in the observation chambers, 15N‐labelled organic nitrogen, as lyophilized and ground mycelium of Suillus variegatus (Swartz: Fr.) O. Kuntze, or ammonium, was added to the peat. The plants were harvested after an uptake period of 14 d.

Irrespective of the nitrogen form added, liming decreased both the content and concentration of 15N in non‐mycorrhizal plants, and, to a lesser extent, those in mycorrhizal plants. In mycorrhizal plants the uptake of 15N was not correlated with area colonized by the mycorrhizal mycelium. The amount of KCl‐extractable 15N in peat without plants and mycorrhizal fungi decreased with liming. It is proposed that liming induced chemical or microbial immobilization of the added 15N. This is suggested to be the main reason for the decreased uptake of 15N in lime treatments.
Biosynthesis in vitro of high‐molecular‐mass fructan by cell‐free extracts from tuberous roots of Viguiera discolor (Asteraceae)
Authors: ITAYA NAIR M. , BUCKERIDGE MARCOS S. , FIGUEIREDO‐RIBEIRO RITA C. L.
Published: March 2003

Tuberous roots of Viguiera discolor accumulate up to 80% of their dry mass as fructans. The distribution pattern of oligomers suggests the predominance of anabolic reactions at the beginning of dormancy, when a continuous series of fructans between sucrose and higher polymers is present. This paper describes the synthesis in vitro of fructans of high molecular mass by enzyme extracts prepared from growing tuberous roots of V. discolor at the beginning of dormancy. Sucrose∶sucrose fructosyl transferase activity was characterized by the synthesis of 1‐kestose from sucrose and fructan∶fructan fructosyl transferase activity by the production of nystose from 1‐kestose. The optimal temperature for both activities was 30°C and the optimal pH range was between 5·5 and 6·0. The apparent Km for sucrose with respect to 1‐kestose synthesis was 173 mol m−3, whereas the Km for nystose synthesis from 1‐kestose was much higher (592 mol m−3). Long incubation periods (up to 264 h) with sucrose, 1‐kestose or nystose produced fructans of high molecular mass in vitro that resembled those found in vivo. Our data show that the higher the molecular mass of the substrate, the higher the average molecular mass of the product that was formed.
Chlorophyll: a symptom and a regulator of plastid development
Authors: THOMAS HOWARD
Published: March 2003

The metabolism of chlorophylls and related tetrapyrroles directly influences, and is influenced by, the proteins and cell structures with which they are associated. During net accumulation, de‐greening and at the steady state chlorophyll and its derivatives are important elements in the post‐translational regulation of the expression of genes for chloroplast proteins. At the same time, they represent potential photodynamic hazards against which green cells need to have protective mechanisms. This review deals with genetic, chemical and environmental perturbations of chlorophyll biosynthesis that impact on protein stability, membrane organization and susceptibility to photodamage. NADPH‐protochlorophyllide oxidoreductase is considered in detail as a pigment– protein regulating, and regulated by, chlorophyll metabolism. The question of the extent and significance of chlorophyll turnover at the steady state is addressed, with particular emphasis on the dynamics of the photosystem II reaction centre. The pathway of chlorophyll catabolism is described, along with its interrelationship with protein mobilization in chloroplast senescence. Finally, the structural basis of pigment‐protein interaction and stability is examined, and the discussion ends by expressing some general thoughts about the control of protein lifetimes in the living cell.

CONTENTS

Summary
163

I.
Introduction
164

II.
Chlorophyll and related tetrapyrroles
164

III.
Chlorophyll‐protein complexes
164

IV.
Chlorophyll biosynthesis
166

V.
NADPH‐protochlorophyllide oxidoreductase
168

VI.
Assembling chlorophyll‐proteins
171

VII.
Chlorophyll turnover at the steady state
172

VIII.
The plastid family tree
173

IX.
The pathway of chlorophyll catabolism
173

X.
Chlorophyll and associated proteins in senescence
175

XI.
How does chlorophyll stabilize associated proteins ?
176

XII.
Conclusion
177

Acknowledgements
177

References
177
ATPase activities of root microsomes from mycorrhizal sunflower (Helianthus annuus) and onion (Allium cepd) plants
Authors: BAGO B. , DONAIRE J. P. , AZCÓN‐AGUILAR C.
Published: March 2003

We compared the plasma membrane, tonoplast and mitochondrial Mg‐ATPase activities of microsomes isolated from mycorrhizal and non‐mycorrhizal sunflower (Helianthus annuus L.) and onion (Allium cepa L.) roots during a time‐course experiment (21–60 d). No significant difference was observed between the protein levels of root microsomes from mycorrhizal and non‐mycorrhizal sunflower. However, the protein content of microsomes obtained from mycorrhizal onion roots increased when the symbiosis was well established (more than 50 % of root length colonized by the arbuscular mycorrhizal fungus). Kinetic studies revealed that vanadate‐sensitive (plasma membrane‐associated) ATPase activity of sunflower root microsomes increased with mycorrhizal colonization. However, the vanadate‐sensitive ATPase activity of microsomes from mycorrhizal onion roots decreased compared with those from non‐mycorrhizal controls. Increased activity of nitrate (tonoplast‐associated) and azide (mitochondrial membrane‐related)‐sensitive ATPase activities was detected in extracts obtained from 45– and 60–d‐old mycorrhizal onion plants. A slight increase in azide‐sensitive ATPase activity was detected in microsomes of mycorrhizal sunflower. The existence of different physiological and biochemical strategies in sunflower and onion in relation to the establishment of this mutualistic symbiosis is discussed.
Influence of leaf water content on the C3–CAM transition in Mesembryanthemum crystallinum
Authors: HERPPICH WERNER B. , HERPPICH MARGARETHA
Published: March 2003

summary

Changes in leaf water content, night‐time accumulation of malic (δ‐malate) and citric acid (δ‐citrate) and phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) activity were followed for 60 d after germination in well watered and salt‐stressed plants of the facultatively halophytic ephemeral Mesembryanthemum crystallinum L. To separate the effects of development, salt stress and water deficit on crassulacean acid metabolism (CAM) induction plants were stressed initially 10 d after germination and then successively at 1‐wk intervals (five sets). Related to dry mass or organic matter (i.e. dry mass corrected for the mass of inorganic ions) water content started to decrease during the late embryonal phase of the life cycle. Water content on a dry mass basis was always lower in salt‐stressed than in well watered individuals. However, on an organic matter basis no difference was detectable. This indicated that salt treatment did not reduce leaf water content but falsified the basis (dry mass). Increases in leaf succulence and in pressure potential prevented long‐term water deficit in well watered and in salt‐stressed plants. Instead, these changes displayed enhanced vacuolisation, which is an essential prerequisite for the development of CAM. The end of that differentiation process might allow the initiation of nocturnal malic acid accumulation in a threshold response. At the onset of each salt treatment, short‐term water deficits occurred due to an incomplete osmotic adaptation independent of plant age. As δ‐malate only appeared when plants were c. 35 d old this water deficit was unlikely to be a decisive CAM‐inducing factor. About 2 wk after germination water content began to decline during the light periods in plants of all treatments. This pattern disappeared again when CAM had been fully established. Daytime transpirational water loss is therefore unlikely to be the decisive factor because it failed to induce the metabolic shift in young plants. Environmental stress (e.g. salt or drought) can therefore only induce δ‐malate when leaf and plant differentiation has reached a certain stage.
High densities of arbuscular mycorrhizal fungi maintained during long fallows in soils used to grow cotton except when soil is wetted periodically
Authors: PATTINSON G. S. , McGEE P. A.
Published: March 2003

Sequential harvests of cotton seedlings grown in soil cores enabled the quantification of the density of arbuscular mycorrhizal fungi to detect the effects of time, cultivation and periodic wetting of the soil. Cotton seedlings grown in soil cores from three locations formed arbuscular mycorrhizas at similar rates when cores were stored dry for up to 18 months. Disturbance of dry cores followed by dry storage for 18 months did not reduce the rate of establishment of mycorrhizas. Periodic wetting and drying of the cores, especially if the cores had first been disturbed, significantly reduced the rate of establishment of mycorrhizas. We suggest that long fallow disorder is possibly caused by falls of rain in clay soils of eastern Australia used to grow cotton. The proportion of the root with mycorrhizas at 3 wk was strongly correlated with the infection at 8 wk. We also suggest that it might be possible to predict maximum levels of infection and early uptake of phosphate of seedlings by determining the proportion of roots that are mycorrhizal 3 wk after emergence of cotton seedlings.
Artificial selection and heritability of ozone resistance in two populations of Plantago major
Authors: WHITFIELD C. P. , DAVISON A. W. , ASHENDEN T. W.
Published: March 2003

summary

Geographically separated populations of Plantago major L. differ in ozone resistance, and this is correlated with the exposure to ozone at the location of each population. In addition, two populations of P. major have been demonstrated to show an increase in ozone resistance after summers when ozone concentrations were high. However, if evolution of ozone resistance has occurred in the field there must be appropriate heritable genetic variation and this must be demonstrated.

In the present study, artificial selection for ozone resistance and sensitivity was imposed on a resistant (‘Lullington Heath’) and sensitive (‘Bush’) population of P. major. Artificial selection is an efficient means of demonstrating additive genetic variance for a character. Selection was based on 2 wk growth in ozone (70 nl O3 1−1for 7 h d−1), and selected lines were tested for ozone resistance under both short and long term ozone exposures. Changes in ozone resistance were demonstrated for each population. On the basis of a 2‐wk screening test, selection from the initially sensitive Bush population led to a line that was significantly more resistant to ozone, but it was not possible to select a line with greater sensitivity than the original population. Conversely, selection from the initially resistant Lullington Heath population led to a line with increased sensitivity but not to a line with increased resistance. Differences in ozone resistance between the selected lines were maintained over the long term and were reflected in growth and seed production at the final harvest. Net assimilation rate, stomatal conductance and leaf pigments were measured. In both populations the lines selected for sensitivity showed a greater effect of ozone on net assimilation rate. Ozone had a minor effect on chlorophyll content in the Lullington Heath sensitive line but tended to increase carotenoid concentrations. However, this effect on carotenoids was not related to ozone resistance.

The experiment demonstrated that ozone resistance in P. major is heritable. The response to selection reported here supports previous evidence from field collections of a rapid evolution of ozone resistance.
The relationship between intracellular pH, growth characteristics and calcium in the cyanobacterium Anabaena sp. strain PCC7120 exposed to low pH
Authors: GIRALDEZ‐RUIZ N. , MATEO P. , BONILLA I. , FERNANDEZ‐PIÑAS F.
Published: March 2003

summary

Changes in various cell functions were examined during a shift of the cyanobacterium Anabaena sp. strain PCC7120 to acidic external pH (pHex) in the presence and absence of added calcium. In the presence of 0–25 mM Ca (the standard Ca concentration of the growth medium), growth and O2 evolution were inhibited at pH values lower than 6. The cyanobacterium was unable to maintain a relatively constant internal pH (pHi) at pH 6 and below, which led to acidification of the cytoplasm. In the absence of Ca, the acidification found at acid pH values was even more pronounced. The elimination of Ca did not affect pHi at pHex of 6–5 and above. Increased acidification of the internal cell contents correlated well with a general impairment of growth in Ca‐deficient cells exposed to external acid pH values. On the other hand, Ca enrichment of cells grown under acidic conditions resulted in a significant improvement of several physiological processes. The protein pattern of cell extracts of Anabaena sp. strain PCC7120 was altered by acidity. The most significant modifications of the protein profiles induced at low pH were not evident in the presence of high concentrations of Ca. Increasing concentrations of Ca allowed Anabaena sp. strain PCC7120 to perform better at lower pH.
Wood decay and phosphorus translocation by the cord‐forming basidiomycete Phanerochaete velutina: the significance of local nutrient supply
Authors: WELLS JOHN M. , BODDY LYNNE , DONNELLY DAMIAN P.
Published: March 2003

Mycelial cord systems of Phanerochaete velutina (DC.: Pers.) Parmasto grown from 4 cm3 inocula on a nutrient‐depleted non‐sterile soil in compartmentalized laboratory microcosms were baited after 13 d of growth with either fresh, non‐sterile 4 cm3 wood blocks or control Perspex® blocks of the same contact area. After 112 d, mature mycelial systems, which were in senescent phase, were subjected to disturbance by supplying a new fresh wood bait diametrically opposite the existing bait and, after 126 d, to nutrient regime amendment by application of NPK solution. At harvest (186 d) there was a significant (P0·001) linear relationship between extra‐resource mycelial biomass and total wood decay over the preceding 74 d. Nutrient amendment alone did not significantly (P>0·05) affect extra‐resource mycelial biomass production or wood decay rates in either disturbed or undisturbed cord systems. However, both mycelial biomass production and resource decay were significantly (P0·05) enhanced when nutrient amendment and disturbance treatments were applied concurrently. Bi‐directional phosphorus translocation to inocula and wood baits (determined non‐destructively) was assessed by labelling the NPK solution applied distal or proximal to the initially supplied bait with 32P. In both disturbed and undisturbed cord systems the rate of 32P uptake from a local supply was two orders of magnitude higher than from a distal supply. In disturbed cord systems uptake of 32P by inocula, which were midway between the two radiotracer supply points, was significantly (P0·05) higher when the supply point contained a newly supplied wood bait. Net translocation of 32P to newly supplied wood baits increased with time at the expense of translocation to inocula and existing wood baits. The switch in direction of net phosphorus translocation, the importance of localized nutrient scavenging and the partitioning of wood decay are discussed in relation to the ecological significance of mycelial cords.