The 12th J. A. F. Stevenson memorial lecture. Aging, Alzheimer's disease, and the cholinergic system

Aging does not affect tissues in a uniform fashion. Within the brain, substantial neuronal dropout occurs with age in the cholinergic medial basal forebrain complex, the noradrenergic locus coeruleus, and the dopaminergic substantia nigra pars compacta. These areas are also struck by diseases that are sharply age dependent. Alzheimer's disease causes neuronal destruction in the cholinergic cells of the medial basal forebrain and noradrenergic cells of the locus coeruleus. Parkinson's disease causes neuronal destruction mainly in the substantia nigra but with some destruction in the locus coeruleus. Parkinsonism-dementia affects all three areas. Alzheimer's disease is responsible for 50-60% of all cases of dementia. Severe dementia rises in frequency from less than 1% of the population at age 65-70 to over 15% by age 85. The cause of the disease is unknown. No method of prevention is known and present treatments are ineffective, although modest improvement has been reported for various therapeutic regimens designed to stimulate the cholinergic system. The neuronal systems identified as being affected in Alzheimer's disease and in the dementia of Parkinsonism correspond with those shown many years ago to be associated with the reticular activating system. This correspondence permits a new hypothesis of cognition and memory to be put forward, as well as a reinterpretation of data from animal research on the reticular activating system performed over a quarter of a century ago. The locus coeruleus is proposed as the noradrenergic element sensitizing the cortex to conscious recognition of real time events. The medial basal forebrain complex is proposed as the system registering the conscious event for storage and as the readout device when it is subsequently redisplayed in the cortex as memory. Storage could either be in the temporal lobe, in several areas of cortex with feedback to the medial basal forebrain, or in the cholinergic cells themselves.     

The persistence of bioluminescent Rhizobium meliloti strains L1 (RecA-) and L33 (RecA+) in non-sterile microcosms depends on the soil type,on the co-cultivation of the host legume alfalfa and on the presence of an indigenous R. meliloti population

In comparative analyses the influence of soil type, the rhizosphere of plants and the presence of an indigenous R. meliloti population on the population dynamics of bioluminescent R. meliloti strains L1 (RecA-) and L33 (RecA+) was assessed in microcosm studies. Both strains established better in a loamy and a clayey soil compared to a sandy soil. RecA- strain L1 showed a slightly but statistically significant reduced survival ability compared to RecA+ strain L33 (p 0.05). The presence of the host plant alfalfa stimulated the growth of both strains in non-sterile soil and no differences in the survival between both strains were observed. Co-cultivation of clover or wheat plants, respectively, neither positively nor negatively influenced the strains' survival. The most pronounced effect on the survival of both strains was exerted by the presence of an indigenous R. meliloti population. RecA- strain L1 showed a significantly impaired survival compared to RecA+ strain L33 (p 0.002). Moreover, no growth stimulation of strains L1 and L33 by the presence of the host plant alfalfa could be observed. These results indicate that the recA mutation affects the long-term rather than the short-term persistence of R. meliloti after environmental release.     

First Records of Dinoflagellates Alexandrium margalefi Balech, 1994 and A. tamutum Montresor, Beran et John, 2004 in the Seas of the Russian Far East

New records of two Alexandrium species are reported for the Russian seas. A. margalefi Balech was found in Peter the Great Bay (Sea of Japan), and A. tamutum Montresor, Beran et John was found in Aniva and Sakhalinskii bays (Sea of Okhotsk). Both species were observed in summer in small numbers at water temperatures of 22– 24°C and 8.6–11°C, respectively. Data on the morphology and distribution of the species is provided.Original Russian Text Copyright © 2005 by Biologiya Morya, Selina, Morozova.     

Morphology of Sinophysis minima sp. nov. and three Sinophysis species (Dinophyceae, Dinophysiales) from the Sea of Japan

Four sand‐dwelling species of the marine dinoflagellate genus Sinophysis, including one new species, have been examined from intertidal and subtidal sand, from the Sea of Japan. The morphological features of these species were observed by light and scanning electron microscopy. Sinophysis minima sp. nov. is flattened laterally and is 17.5–35.0 μm in length and 15.0–27.5 μm in depth, with a length/depth ratio of 1.1–1.4, an epitheca depth of 5.0–7.5 μm, and a sulcus length of about three‐quarters the hypotheca length. Sinophysis ebriola (Herdman) Balech, Sinophysis grandis Hoppenrath and Sinophysis stenosoma Hoppenrath were recorded for the first time in the seas of Russia. Sinophysis stenosoma is the most common species in the Sea of Japan. All species usually occurred together in the region investigated. Additional information on the known species is provided.     

The effect of a range of biological polymers and synthetic surfactants on the adhesion of a marine Pseudomonas sp. strain NCMB 2021 to hydrophilic and hydrophobic surfaces

Abstract The effect of a range of biological polymers and synthetic surfactants on the adhesion of a marine Pseudomonas sp. strain NCMB2021 to hydrophilic glass and hydrophobic polystyrene has been investigated. Brij 56 (polyethylene oxide (10) cetyl ether) was the only compound that had a significant effect, almost totally inhibiting the adhesion of Pseudomonas sp. NCMB2021 to hydrophobic polystyrene, but having little or no effect on hydrophilic glass. The surfactant was demonstrated to be effective both when present in the bacterial suspension at low concentrations (approx. 5 ppm), and when pre-adsorbed onto the substratum. Brij 56 was shown to prevent the adhesion of a range of marine and fresh-water bacteria to polystyrene.
It is proposed that on a hydrophobic substratum Brij 56 is adsorbed via its hydrophobe in such a way that the polyethylene glycol chains are pointing outwards into the aqueous phase giving a surface with a high density of uncharged, highly hydrated hydrophilic chains, forming a steric barrier which inhibits the adhesion of bacteria.     

PmMGST3, a novel microsomal glutathione S-transferase gene in the dinoflagellate Prorocentrum minimum, is a potential biomarker of oxidative stress

In this study, we evaluated a novel microsomal glutathione S-transferase3 (MGST3) gene from the dinoflagellate Prorocentrum minimum, and examined its expression pattern in response to copper-and nickel-induced stresses. The full length of PmMGST3 was 732 bp, ranging from the dinoflagellate splice leader (DinoSL) sequence to the poly (A) tail, covering a 441-bp ORF, 97-bp 5′UTR, and 194-bp 3′UTR. The PmMGST3 was up-regulated by metals, including copper and nickel. The highest up-regulation levels of the PmMGST3 were found under 0.1 mg/L copper and 0.5 mg/L nickel treatment, respectively. In addition, the PmMGST3 was gradually up-regulated by 0.1 mg/L copper with increasing exposure time. Furthermore, ROS production and reduced GSH was measured in the copper treated cells. A significant increased ROS production and reduced GSH were found in the copper treated cells. These results suggest that PmMGST3 may be related to defense mechanisms associated with oxidative stress in dinoflagellates.     

The effect of growth phase on the lipid class,fatty acid and sterol composition in the marine dinoflagellate,Gymnodinium sp. in batch culture

We have studied the effects of growth phase on the lipid composition in batch cultures of Gymnodinium sp. CS-380/3 over 43 days of culturing. The lipid content increased two fold, from late logarithmic (day 6) to linear growth phase (day 22) then decreased at stationary phase (day 43) while the lipid yield (mg l(-1)) increased 30-fold from day 6 to 30 mg l(-1) at day 43. Changes in fatty acid content mirrored those observed for the total lipid, while the sterol content continued to increase with culture age through to stationary phase. The largest changes occurred in the lipid classes, especially the polar lipids and triacylglycerols (oil). The proportion of triacylglycerols increased from 8% (of total lipids) at day 6 to 30% at day 43, with a concomitant decrease in the polar lipid fraction. The proportions of 16:0 and DHA [22:6(n-3)] increased while those of 18:5(n-3) and EPA [20:5(n-3)] decreased with increasing culture age. The proportion of the major sterol, dinosterol, decreased from 41% (day 6) to 29% (day 43), while the major dinostanol epimer (23R,24R) increased from 33% (day 6) to 38% (day 22). Despite small changes in the proportion of the main sterols, the same sterols were present at all stages of growth, indicating their value as a chemotaxonomic tool for distinguishing between strains within the same genus. Growth phase could be a useful variable for optimising the oil and DHA content with potential for aquaculture feeds and a source of DHA-rich oils for nutraceuticals.     

The morphology,innervation and neural control of the anterior arterial system of Aplysia californica

Summary The morphology, innervation, and neural control of the anterior arterial system of Aplysia californica were investigated. Immunocytochemical and histochemical techniques generated positive reactions in the anterior arterial system for several neuroactive substances, including SCP_B, FMRFamide, R151 peptide, dopamine and serotonin. Three neurons were found to innervate the rostral portions of the anterior arterial tree. One is the identified peptidergic neuron R15 in the abdominal ganglion, and the other two are a pair of previously unidentified neurons, one in each pedal ganglion, named pedal arterial shorteners (P_AS)- The endogeneously bursting neuron R15 was found to innervate the proximal anterior aorta. It also innervates a branch of the distal anterior aorta, the left pedal-parapodial artery. Activity in R15 causes constriction of the left pedal-parapodial artery. This effect is presumed to direct hemolymph towards the genital groove and penis on the right side in vivo. This vasoconstrictor action of R15 is mimicked by the R151 peptide. The P_AS neuron pair causes longitudinal contraction of the rostral anterior aorta and the pedal-parapodial arteries. In vivo, the pair is active during behaviors involving head withdrawal and turning. By adjusting the length of the arteries during postural changes, the P_AS neurons may prevent disturbances in blood flow due to bending or kinking of the arterial walls.     

桑-蚕系统中镉的吸收、累积与迁移

对桑－蚕系统中镉的吸收,累积与迁移行为研究结果表明：（１）桑树对土壤镉污染有一定的耐性,桑树镉累积量和相对累积率与土壤镉浓度的关系可分别用回归方程Ｔａ＝ａ＋ｂｌｏｇ（Ｓｃ）和ｌｏｇ（Ｒａ）＝ａ＋ｂｌｏｇ（Ｓｃ）描述。（２）随着土壤镉浓度的增加,镉在桑树根部的分布率明显增加,地上部分的分布率有所降低,运转到叶片的比率明显降低。（３）蚕体,蚕砂和蚕茧的镉含量,镉累积量,随着桑叶镉含量的增加而增加。     

Morphology and toxicology of Prorocentrum arabianum sp. nov., (dinophyceae) a toxic planktonic dinoflagellate from the Gulf of Oman, Arabian Sea

A new species of planktonic dinoflagellate, Prorocentrum arabianum isolated from the Gulf of Oman, is described using both scanning electron microscopy (SEM) and light microscopy. This clonal isolate has the following morphological characteristics: (1) cell shape is asymmetric; (2) thecal surface is rugose, covered with small poroids; (3) periflagellar area is unornamented, and (4) intercalary band is horizontally striated. Analysis of P. arabianum confirms the production of one cytotoxic compound and one ichthyotoxic compound. P. arabianum is the second known toxic planktonic Prorocentroid dinoflagellate.     

Paralytic shellfish toxin profile in strains of the dinoflagellate Gymnodinium catenatum Graham and the scallop Argopecten ventricosus G.B. Sowerby II from Bahía Concepción, Gulf of California, Mexico

Gymnodinium catenatum Graham is a paralytic shellfish poison (PSP) producer that was described for the first time from the Gulf of California in 1943. During the last decade, its distribution along the Mexican Pacific coastline has increased. In Bahía Concepción, a coastal lagoon on the western side of the Gulf of California, G. catenatum has been linked to significant PSP concentrations found in mollusks. In this study, we describe the saxitoxin profile of 16 strains of G. catenatum, and catarina scallops (Argopecten ventricosus) from Bahía Concepción. Toxins were analyzed by HPLC with post-column oxidation and fluorescence detection. The average toxicity of the G. catenatum strains was 26.0±6.0 pg and 28.0±18.0 pg STX eq/cell after 17 and 22 days of growth, respectively. Ten toxins were recorded, but only dcSTX, dcGTX2, dcGTX3, C1, and C2 were always present in all strains at both growth stages. Since toxin profiles in scallops were similar to the cultures, biotransformations are not significant in catarina scallop. NeoSTX, GTX2, GTX3, and B2 were present in some G. catenatum strains and their presence varied with the age of the culture. In scallop samples, dcSTX, dcGTX2, and dcGTX3 were the most abundant toxins, and from the C-toxin group, only C2 was found. This unique toxin profile can be used as a biomarker for this population, when compared with strains of G. catenatum from other geographic regions.     

Tight,cell type-specific control of LNX expression in the nervous system,at the level of transcription,translation and protein stability

LNX1 and LNX2 are E3 ubiquitin ligases that can interact with Numb — a key regulator of neurogenesis and neuronal differentiation. LNX1 can target Numb for proteasomal degradation, and Lnx mRNAs are prominently expressed in the nervous system, suggesting that LNX proteins play a role in neural development. This hypothesis remains unproven, however, largely because LNX proteins are present at very low levels in vivo. Here, we demonstrate expression of both LNX1 and LNX2 proteins in the brain for the first time. We clarify the cell-type specific expression of LNX isoforms in both the CNS and PNS, and identify a novel LNX1 isoform. Using luciferase reporter assays, we show that the 5′ untranslated region of the Lnx1_variant 2 mRNA, that generates the LNX1p70 isoform, strongly suppresses protein production. This effect is mediated in part by the presence of upstream open reading frames (uORFs), but also by a sequence element that decreases both mRNA levels and translational efficiency. By contrast, uORFs do not negatively regulate LNX1p80 or LNX2 expression. Instead, we find some evidence that protein turnover via proteasomal degradation may influence LNX1p80 levels in cells. These observations provide plausible explanations for the low levels of LNX1 proteins detected in vivo.     

The endocrine cells in the gastroenteropancreatic system of the bowfin, Amia calva L.: an immunohistochemical, ultrastructural, and immunocytochemical analysis.

The gastroenteropancreatic (GEP) endocrine system of bowfin (Amia calva) was described using light and electron microscopy and immunological methods. The islet organ (endocrine pancreas) consists of diffusely scattered, mostly small islets and isolated patches of cells among and within the exocrine acini. The islets are composed of abundant, centrally located B cells immunoreactive to bovine and lamprey insulin antisera and D cells showing a widespread distribution and specificity to somatostatin antibodies. A and F cells are present at the very periphery of the islets and are immunoreactive with antisera against glucagon (and glucagon-like peptide) and several peptides of the pancreatic polypeptide (PP)-family, respectively. The peptides of the two families usually collocates within the same peripheral islet cells and are the most common immunoreactive peptides present in the extra-islet tissue. Immunocytochemistry and fine structural observations characterised the granule morphology for B and D cells and identified two cell types with granules immunoreactive to glucagon antisera. These two putative A cells had similar granules, which were distinct from either B or D cells, but one of the cells had rod-shaped cytoplasmic inclusions within cisternae of what appeared to be rough endoplasmic reticulum. The inclusions were not immunoreactive to either insulin or glucagon antisera. Only small numbers of cells in the stomach and intestine immunoreacted to antisera against somatostatin, glucagon, and PP-family peptides. The paucity of these cells was reflected in the low concentrations of these peptides in intestinal extracts. The GEP system of bowfin is not unlike that of other actinopterygian fishes, but there are some marked differences that may reflect the antiquity of this system and/or may be a consequence of the ontogeny of this system in this species.     

The mammalian Crx genes are highly divergent representatives of the Otx5 gene family,a gnathostome orthology class of orthodenticle-related homeogenes involved in the differentiation of retinal photoreceptors and circadian entrainment

The mammalian Crx genes are highly divergent orthodenticle (otd)-related homeogenes that play important roles in the differentiation of retinal photoreceptors and the circadian entrainment. However, their evolutionary origin and orthological relationships with other otd-related genes remain unclear. An orthology relationship of these genes with the highly conserved Otx5 genes identified in fish and amphibians, and also expressed in the eye and epiphysis, has been proposed previously but remains controversial. To test this hypothesis, we have identified Crx genes in a wide range of mammals, including three marsupials, and Otx5-related genes in a lizard, a turtle, and two archosaurs (crocodile and chick), as well as in the pufferfish. Phylogenetic analyses of the coding sequences show that the mammalian Crx genes are orthologous to the Otx5-related genes isolated in other gnathostomes. They also indicate that a duplication event has taken place in actinopterygians, after the splitting of the Cladistia, and that a relaxation of the structural constraints acting on the gene coding region has occurred early in the mammalian lineage. This process may be linked not only to the loss of ancestral Otx5/Crx functions during gastrulation or in the retinal pigmented epithelium, but also to the evolution of photic entrainment mechanisms in mammals.     

The α-gliadin gene family. I. Characterization of ten new wheat α-gliadin genomic clones, evidence for limited sequence conservation of flanking DNA, and Southern analysis of the gene family

 A detailed study of the organization of the wheat α-gliadin gene family is described. In the first stage of this study recombinant libraries of sufficient size and quality were constructed to allow examination of large, closely-related, gene families. A large number of α-gliadin clones were then isolated in a partial screen of these libraries. A set of these clones were sequenced and ten new gene sequences are now reported. Including these new sequences, 20 of the 27 known α-gliadin genomic and cDNA sequences are from cv Cheyenne, making this cultivar the best studied for gliadin family organization. An analysis of the DNA flanking the coding regions shows divergences which may indicate the functional ends of the α-gliadin genes. High-resolution Southern analyses on DNA from aneuploid and chromosome-substitution lines allow most of the 20 distinct α-gliadin HindIII restriction fragments in cvs Cheyenne and Chinese Spring to be assigned to specific genomes. It is estimated that as many as 150 α-gliadin genes occur in the cultivar Cheyenne, and the limitations of such estimates are discussed. Received: 1 October 1996 / Accepted: 20 December 1996