bluuebunny/crossref_metadata_2025 huggingface dataset:
ADAM2 promotes migration of neuroblasts in the rostral migratory stream to the olfactory bulb
Authors: Murase Shin‐ichi , Cho Chunghee , White Judith M. , Horwitz Alan F.
Published: March 2008

Neuroblasts migrate from the subventricular zone along the rostral migratory stream (RMS) to the olfactory bulb (OB). While the migration occurs by movement over other cells, the molecular mechanisms are poorly understood. We have found that ADAM2 (a disintegrin and metalloprotease 2) is expressed in migrating RMS neuroblasts and functions in their migration. The brains from ADAM2 knockout (KO) mice showed a smaller OB than that seen in wild‐type (WT) mice at postnatal day 0. In addition, the RMS in ADAM2 KO mice appeared thinner and less voluminous in its rostral part and thicker in its caudal part. Estimates of migration in vivo using bromodeoxyuridine labeling revealed that neuroblasts from KO mice show a decreased migration rate compared with those from WT mice. Direct assays of migration by imaging living slices also showed a decreased migration speed and loss of directionality in the KO mice. This phenotype was similar to that seen in RMS containing slices from WT mice exposed to a peptide that mimicked the disintegrin loop of ADAM2. Finally, RMS explants from KO or WT mice that were cultured in Matrigel also revealed striking differences. The cells migrating out of explants from WT mice showed robust cell–cell interactions. In contrast, fewer cells migrated out of explants from ADAM2 KO mice, and those that did were largely dispersed and their migration inhibited. These experiments suggest that ADAM2 contributes to RMS migration, possibly through cell–cell interactions that mediate the rapid migration of the neuroblasts to their endpoint.
Sleep architecture of the melanin‐concentrating hormone receptor 1‐knockout mice
Authors: Adamantidis Antoine , Salvert Denise , Goutagny Romain , Lakaye Bernard , Gervasoni Damien , Grisar Thierry , Luppi Pierre‐Hervé , Fort Patrice
Published: March 2008

Growing amounts of data indicate involvement of the posterior hypothalamus in the regulation of sleep, especially paradoxical sleep (PS). Accordingly, we previously showed that the melanin‐concentrating hormone (MCH)‐producing neurons of the rat hypothalamus are selectively activated during a PS rebound. In addition, intracerebroventricular infusion of MCH increases total sleep duration, suggesting a new role for MCH in sleep regulation. To determine whether activation of the MCH system promotes sleep, we studied spontaneous sleep and its homeostatic regulation in mice with deletion of the MCH‐receptor 1 gene (MCH‐R1–/– vs. MCH‐R1+/+) and their behavioural response to modafinil, a powerful antinarcoleptic drug. Here, we show that the lack of functional MCH‐R1 results in a hypersomniac‐like phenotype, both in basal conditions and after total sleep deprivation, compared to wild‐type mice. Further, we found that modafinil was less potent at inducing wakefulness in MCH‐R1–/– than in MCH‐R1+/+ mice. We report for the first time that animals with genetically inactivated MCH signaling exhibit altered vigilance state architecture and sleep homeostasis. This study also suggests that the MCH system may modulate central pathways involved in the wake‐promoting effect of modafinil.
Generation recruitment and death of brain cells throughout the life cycle ofSorexshrews (Lipotyphla)
Authors: Bartkowska Katarzyna , Djavadian Rouzanna L. , Taylor Jan R. E. , Turlejski Kris
Published: March 2008

Young shrews of the genusSorexthat are born in early summer reduce their body size before wintering, including a reduction of brain weight of 10–30%. In the spring they mature sexually, double their body weight and regain about half of the loss in brain weight. To investigate the mechanisms of brain weight oscillations we studied the rate of cell death and generation in the brain during the whole life cycle of the common shrew (Sorex araneus) and pygmy shrew (S. minutus). After weaning, shrews generate new brain cells in only two mammalian neurogenic zones and approximately 80% of these develop into neurones. The increase of the shrew brain weight in the spring did not depend on recruitment of new cells. Moreover, adultSorexshrews did not generate new cells in the dentate gyri. Injections of 5‐HT1A receptor agonists in the adult shrews induced neurogenesis in their dentate gyri, showing the presence of dormant progenitor cells. Generation of new neurones in the subventricular zone of the lateral ventricles and their recruitment to olfactory bulbs continued throughout life. TUNEL labelling showed that the rate of cell death in all brain structures, including the proliferation zones and olfactory bulb, was very low throughout life. We conclude that neither cell death nor recruitment significantly contributes to seasonal oscillations and the net loss of brain weight in theSorexshrews. With the exception of dentate gyrus and olfactory bulb, cellular populations of brain structures are stable throughout the life cycle of these shrews.
Endothelial cell‐derived bone morphogenetic proteins regulate glial differentiation of cortical progenitors
Authors: Imura Tetsuya , Tane Kotoha , Toyoda Nana , Fushiki Shinji
Published: March 2008

Gliogenesis is an important component of cortical development during the postnatal period. Two macroglial cells are generated in a particular order, i.e. astrocytes first and oligodendrocytes later. The mechanisms underlying this sequence of glial differentiation are unknown but interactions with blood vessels are postulated to play a role. We show, using a mouse in‐vitro coculture system, that endothelial cells promote astrocyte differentiation but inhibit oligodendrocyte differentiation of postnatal cortical progenitors. Endothelial cells produce bone morphogenetic proteins (BMPs) to activate Sma‐ and Mad‐related protein (Smad) signalling in progenitors and the effects of endothelial cells on glial differentiation are blocked by the BMP antagonist Noggin. Differentiation of progenitors into astrocytes results in the inhibition of endothelial cell growth, accompanied by changes in gene expression of angiogenic factors, indicating bidirectional interactions between progenitors and endothelial cells. In vivo, Smad signalling is activated in various types of cortical cells including progenitors in association with astrogenesis but is inactivated before the peak of oligodendrogenesis. Capillary vessels isolated from the developing cortex express high levels of BMPs. Together, these results demonstrate that endothelial cells regulate glial differentiation by secreting BMPs in vitro and suggest a similar role in cortical gliogenesis in vivo.
ALG‐2 interacting protein AIP1: a novel link between D1 and D3 signalling
Authors: Zhan Lingping , Liu Bigang , Jose‐Lafuente Maria , Chibalina Margarita V. , Grierson Andrew , Maclean Alan , Nasir Jamal
Published: March 2008

Dopamine signalling is a critically important process in the human brain that controls mood, cognition and motor activity. In order to gain detailed insight into this signalling pathway at the molecular level, we carried out yeast two‐hybrid screens with D1‐like (D1, D5) and D2‐like (D2, D3, D4) dopamine receptors and identified 11 dopamine receptor interacting proteins (DRIPs). Using the C‐terminal domain of D1 receptor as bait, we identified AIP1 (ALG‐2 interacting protein 1), a known modulator of caspase‐dependent and caspase‐independent cell death, including neuronal cell death, that is also part of the endosomal transport system. In a separate yeast two‐hybrid screen, using the third intracellular cytoplasmic loop of D3 as bait, we again identified AIP1. The interaction of AIP1 with both D1 and D3 was confirmed in vitro and in vivo using a variety of methods, including glutathione S‐transferase (GST) pull‐down, blot overlay and coimmunoprecipitation from mouse brain lysates. We have also observed colocalization of D1 and D3 with AIP1 in mouse brain tissue. In addition, coexpression of AIP1 with D1 resulted in > 50% reduction in binding capacity of D1 to its antagonist. Finally, AIP1 up‐regulates D1 and D3 expression and appears to be important for their stability and trafficking.
Differential synaptic plasticity of the corticostriatal and thalamostriatal systems in an MPTP‐treated monkey model of parkinsonism
Authors: Raju Dinesh V. , Ahern Todd H. , Shah Deep J. , Wright Terrence M. , Standaert David G. , Hall Randy A. , Smith Yoland
Published: March 2008

Two cardinal features of Parkinson's disease (PD) pathophysiology are a loss of glutamatergic synapses paradoxically accompanied by an increased glutamatergic transmission to the striatum. The exact substrate of this increased glutamatergic drive remains unclear. The striatum receives glutamatergic inputs from the thalamus and the cerebral cortex. Using vesicular glutamate transporters (vGluTs) 1 and 2 as markers of the corticostriatal and thalamostriatal afferents, respectively, we examined changes in the synaptology and relative prevalence of striatal glutamatergic inputs in methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐treated monkeys using electron microscopic immunoperoxidase and confocal immunofluorescence methods. Our findings demonstrate that the prevalence of vGluT1‐containing terminals is significantly increased in the striatum of MPTP‐treated monkeys (51.9 ± 3.5% to 66.5 ± 3.4% total glutamatergic boutons), without any significant change in the pattern of synaptic connectivity; more than 95% of vGluT1‐immunolabeled terminals formed axo‐spinous synapses in both conditions. In contrast, the prevalence of vGluT2‐immunoreactive terminals did not change after MPTP treatment (21.7 ± 1.3% vs. 21.6 ± 1.2% total glutamatergic boutons). However, a substantial increase in the ratio of axo‐spinous to axo‐dendritic synapses formed by vGluT2‐immunoreactive terminals was found in the pre‐caudate and post‐putamen striatal regions of MPTP‐treated monkeys, suggesting a certain degree of synaptic reorganization of the thalamostriatal system in parkinsonism. About 20% of putative glutamatergic terminals did not show immunoreactivity in striatal tissue immunostained for both vGluT1 and vGluT2, suggesting the expression of another vGluT in these boutons. These findings provide striking evidence that suggests a differential degree of plasticity of the corticostriatal and thalamostriatal system in PD.
Learning‐related changes in reward expectancy are reflected in the feedback‐related negativity
Authors: Bellebaum Christian , Daum Irene
Published: March 2008

The feedback‐related negativity (FRN) has been hypothesized to be linked to reward‐based learning. While many studies have shown that the FRN only occurs in response to unexpected negative outcomes, the relationship between the magnitude of negative prediction errors and FRN amplitude remains a matter of debate. The present study aimed to elucidate this relationship with a new behavioural procedure that allowed subjects to predict precise reward probabilities by learning an explicit rule. Insight into the rule did not only influence subjects' choice behaviour, but also outcome‐related event‐related potentials. After subjects had learned the rule, the FRN amplitude difference between non‐reward and reward mirrored the magnitude of the negative prediction error, i.e. it was larger for less likely negative outcomes. Source analysis linked this effect to the anterior cingulate cortex. P300 amplitude was also modulated by outcome valence and expectancy. It was larger for positive and unexpected outcomes. It remains to be clarified, however, whether the P300 reflects a positive prediction error.
Tau expression levels from various adeno‐associated virus vector serotypes produce graded neurodegenerative disease states
Authors: Klein Ronald L. , Dayton Robert D. , Tatom Jason B. , Diaczynsky Cynthia G. , Salvatore Michael F.
Published: March 2008

Neurodegenerative diseases involving neurofibrillary tangle pathology are pernicious. By expressing the microtubule‐associated protein tau, a major component of tangles, with a viral vector, we induce neuropathological sequelae in rats that are similar to those seen in human tauopathies. We tested several variants of the adeno‐associated virus (AAV) vector for tau expression in the nigrostriatal system in order to develop models with graded onset and completeness. Whereas previous studies with AAV2 tau vectors produced partial lesions of the nigrostriatal system, AAV9 or AAV10 tau vectors were more robust. These vectors had formidable efficacy relative to 6‐hydroxydopamine for dopamine loss in the striatum. Time‐courses for tau transgene expression, dopamine loss and rotational behavior tracked the disease progression with the AAV9 tau vector. There was a nearly complete lesion over a delayed time‐course relative to 6‐hydroxydopamine, with a sequence of tau expression by 1 week, dopamine loss by 2 weeks and then behavior effect by 3–4 weeks. Relative to AAV2 or AAV8, tau expression from AAV9 or AAV10 peaked earlier and caused more dopamine loss. Varying vector efficiencies produced graded states of disease up to nearly complete. The disease models stemming from the AAV variants AAV9 or AAV10 may be useful for rapid drug screening, particularly for tau diseases that affect the nigrostriatal system, such as progressive supranuclear palsy.
Imbrication of the external anal sphincter may yield similar functional results as overlapping repair in selected patients
Authors: Oberwalder M. , Dinnewitzer A. , Nogueras J. J. , Weiss E. G. , Wexner S. D.
Published: March 2008

Objective  Overlapping external anal sphincter repair is the preferred procedure for incontinent patients with functional yet anatomically disrupted anterior external anal sphincter. When incomplete disruption, thinning or technically difficult mobilization of the external anal sphincter occurs, imbrication without division may be the more feasible surgical option. The aim of the study was to assess retrospectively the indications for external anal sphincter imbrication in patients who underwent either overlapping external anal sphincter repair or external anal sphincter imbrication, and to compare the success rates.

Method  Patients who had external anal sphincter repair and follow up of at least 3 months were studied. Fecal incontinence was measured using the validated Wexner fecal Incontinence Scoring system (0 = perfect continence, 20 = complete incontinence); postoperative scores 0–10 were interpreted as successful, and scores of 11–20 as failures.

Results  A total of 131 females who had anal sphincter repair between 1988 and 2000 were analysed. One hundred and twenty‐one patients had overlapping external anal sphincter repair (group I), and 10 had external anal sphincter imbrication (group II). Indications for external anal sphincter imbrication were attenuation of the external anal sphincter without overt defect (n = 5), partial disruption of external anal sphincter with muscle fibres bridging the scar (n = 2), thick bulk of scar between the muscle edges (n = 2), and wide lateral retraction of the muscle edges (n = 1). There were no statistically significant differences between the groups relative to preoperative incontinence score (16.5 vs 16.5, P = 0.99), pudendal nerve terminal motor latency assessment (left 9.6%vs 0.0%, P = 0.19; right 13.4%vs 11.1%, P = 0.84), and extent of electromyography pathology (61%vs 47%, P = 0.30). The patients in group I were younger than those in group II (mean age 50.8 years vs. 61.7 years, respectively; P = 0.052) and the length of follow‐up was significantly longer (32.3 months vs 14.3 months, respectively; P < 0.0001). Both procedures had similar success rates (59.5%vs 60%; P = 0.98).

Conclusion  Imbrication of the external anal sphincter may yield similar results as overlapping external anal sphincter repair in patients with incomplete external anal sphincter disruptions, external anal sphincter attenuation, and in patients presenting with wide lateral retraction of the muscle edges.
Awareness of risk factors amongst first degree relative patients with colorectal cancer
Authors: Akhtar S. , Sinha S. , McKenzie S. , Sagar P. M. , Finan P. J. , Burke D.
Published: March 2008

Background  The association between family history of colorectal cancer (CRC) in first degree relatives (FDRs) and the risk of developing the disease has been well established. However, little is known about the degree of awareness of CRC risk factors amongst FDRs. This study examined awareness of familial, dietary and lifestyle risk amongst FDRs.

Method  Consent to approach relatives was obtained from CRC patients who attended outpatients following surgery for CRC. A study specific questionnaire was sent by post to their FDRs. The dietary and lifestyle risk factors tested in the questionnaire were those promoted in CRC educational material.

Results  One hundred and four questionnaires were returned out of 137 sent (76%). Fifty‐nine per cent (n = 61) of FDRs were aware of their increased risk. Fifty‐five per cent (n = 57) were aware of the link between CRC and smoking; however, knowledge of association of CRC with excessive alcohol consumption (32%) and lack of exercise (40%) was less well appreciated. Higher awareness scores were obtained by those with a university education (P < 0.001). Ninety four per cent believed that relatives of CRC patients were not provided with enough information as to their being at risk and risk factors.

Conclusions  This study provides an initial assessment of the awareness of CRC risk factors in a population at increased risk. It demonstrates a poor level of knowledge. Improved education strategies allowing FDRs to make dietary and lifestyle modifications that could reduce their lifetime risk of developing CRC are necessary.
A novel exocrine gland in the trochanter of ant legs
Authors: Billen Johan
Published: March 2008

We found a hitherto unknown gland in the trochanter of several ant species. The gland occurs at the proximal ventral part of the trochanter in all legs. It consists of a thickening of the tegumental epithelium, the lining cuticle of which is characterized by narrow vertical pores that lead the secretion to the outside. Its function is probably that of producing lubricant substances to allow optimal manoeuvrability of the articulation between the trochanter and the coxa.
Is the End of the MFA a Threat?
Authors: Marouani Mohamed Ali
Published: March 2008

The end of the Multifiber Agreement in January, 2005 had a negative impact on the apparel industry of regional exporters, but the effects were weaker than expected. Using a dynamic general equilibrium model, the article provides a prospective assessment of the impact on Tunisia of the phase out of the MFA, and of the agreement which manages the rate of growth of Chinese clothing exports to Europe, until the end of 2007. The main findings are an increase in unemployment and wage inequality but no significant effects on the main macroeconomic variables, if the exchange rate management takes into account this shock.
Globalization and Taste Convergence: the Cases of Wine and Beer
Authors: Aizenman Joshua , Brooks Eileen
Published: March 2008

This paper investigates changes in cultural consumption patterns for a low‐concentration industry: wine and beer. Using data on 38 countries from 1963–2000, there is clear convergence in the consumption of wine relative to beer between 1963 and 2000. Convergence occurs even more quickly within groups of countries that have a higher degree of integration. A key prediction of international trade is confirmed in the data: greater trade integration weakens the association between production and consumption patterns—although the relative consumption of wine can be explained well in 1963 by grape production and latitude, these variables are much less significant in 2000. Despite these “scientific” explanations, there is also a cultural angle to wine consumption. While the relative wine consumption of France and Germany is converging, several Latin American countries fail to converge. The patterns of convergence are consistent with dynamics of adjustment in overlapping generation habit formation models.
On the Number of Solutions to Carrier's Problem
Authors: Wong R. , Zhao Y.
Published: March 2008

Let Nɛ denote the maximum number of spikes that a solution to Carrier's problem

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can have, where ɛ is a small positive parameter. We show that Nɛ is asymptotically equal to [K/ɛ], where K= 0.4725⋯, and the square brackets represent the greatest integer less than or equal to the quantity inside. If n(ɛ) stands for the number of solutions to this problem, then it is also shown that 4Nɛ− 3 ≤n(ɛ) ≤ 4Nɛ. Our approach is based on the shooting method used by Ou and Wong (Stud. Appl. Math. 111 (2003)) and on the construction of an envelope function for the minimum values of the solutions as ɛ approaches zero.
Accelerated Imaginary‐time Evolution Methods for the Computation of Solitary Waves
Authors: Yang Jianke , Lakoba Taras I.
Published: March 2008

Two accelerated imaginary‐time evolution methods are proposed for the computation of solitary waves in arbitrary spatial dimensions. For the first method (with traditional power normalization), the convergence conditions as well as conditions for optimal accelerations are derived. In addition, it is shown that for nodeless solitary waves, this method converges if and only if the solitary wave is linearly stable. The second method is similar to the first method except that it uses a novel amplitude normalization. The performance of these methods is illustrated on various examples. It is found that while the first method is competitive with the Petviashvili method, the second method delivers much better performance than the first method and the Petviashvili method.
Merit in the Midst of Grace: The Covenant with Adam Reconsidered in View of the Two Powers of God
Authors: WOOD JOHN HALSEY
Published: March 2008

Abstract:  The position of Barth and others, that the covenant with Adam is thoroughly legalistic, is based on the incorrect assumption that grace and works cannot coexist as covenant principles. However, the difficulty of seeing the harmony between these principles is real. This article reconsiders the covenant with Adam in light of the medieval concept of the two powers of God, or as we shall argue here, the two perspectives on God's power. These two perspectives, part of the original intellectual milieu in which covenant theology arose, demonstrate that the divine covenant with humanity may include aspects of both God's grace and human merit simultaneously. God's grace is apparent de potentia absoluta, from the perspective of God's absolute power, and God's justice and the possibility of Adam's merit are apparent de potentia ordinata, from the perspective of God's ordained power. Both perspectives, what God could do and what he has in fact chosen to do, are valid and necessary perspectives for understanding God's covenant dealings.
Comparison of CGRP and NO Responses in the Human Peripheral Microcirculation of Migraine and Control Subjects
Authors: Edvinsson M-L , Edvinsson L
Published: March 2008

Calcitonin gene-related peptide (CGRP) and nitric oxide (NO) are two molecules shown to have a role in migraine pathophysiology. Our objective was to test the hypothesis that migraine subjects are particularly sensitive to these signal molecules. The cutaneous microvascular responses to endothelial and non-endothelial dependent dilators were tested using laser Doppler flowmetry in combination with iontophoresis. The blood flow responses to iontophoretic administration of the endothelium-dependent vasodilator acetylcholine (ACh), or to the endothelium-independent dilators sodium nitroprusside (SNP) and CGRP, and to local warming (44 °C) were compared in this controlled trial. The design was that of two arms: patients diagnosed with migraine without aura ( n = 9) for >10 years were compared with nine healthy subjects matched for age and gender (seven female and two male, age range 30-60 years). Iontophoretic administration resulted in local vasodilation. ACh induced a relaxation of 1225 ± 245% (relative to baseline) in controls and 1468 ± 368% ( P > 0.05) in migraine. The responses to SNP were 873 ± 193% in controls and 1080 ± 102% ( P > 0.05) in migraine subjects. The responses to CGRP were 565 ± 89% in controls and 746 ± 675% ( P > 0.05) in migraine patients. The responses to local heating which induced maximum dilation did not differ between the groups (1976 ± 314% for controls and 1432 ± 226% in migraine; P > 0.05. We conclude that there is no change in the microvascular responsiveness of the subcutaneous microvasculature in migraine.
Familial Hemiplegic Migraine Type 1 Shows no Hypersensitivity to Nitric Oxide
Authors: Hansen JM , Thomsen LL , Olesen J , Ashina M
Published: March 2008

Familial hemiplegic migraine type 1 (FHM-1) is a dominantly inherited subtype of migraine with aura and transient hemiplegia associated with mutations in the CACNA1A gene. FHM-1 shares many phenotypical similarities with common types of migraine, indicating common neurobiological pathways. Experimental studies have established that activation of the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway plays a crucial role in migraine pathophysiology. Therefore, we tested the hypothesis that CACNA1A mutations in patients with FHM-1 are associated with hypersensitivity to NO-cGMP pathway. We included eight FHM-1 patients with R583Q and C1369Y mutations and nine healthy controls, who received intravenous infusions of 0.5 μg kg−1 min−1 glyceryl trinitrate (GTN) over 20 min. We recorded: headache intensity on a verbal rating scale; mean flow velocity in the middle cerebral artery (VmeanMCA) by transcranial Doppler; diameter of the superficial temporal artery (STA) by Dermascan. One patient reported migraine without aura 5 h after start of the GTN infusion. No aura was reported. The AUCheadache in the immediate phase was more pronounced in patients than in controls ( P = 0.01). In the 14 h following GTN infusion, there was no difference in the AUCheadache between patients and controls ( P = 0.17). We found no difference in the AUCVmeanMCA ( P = 0.12) or AUCSTA ( P = 0.71) between FHM-1 patients and controls. None of the control persons reported migraine-like headache. FHM-1 patients do not show hypersensitivity of the NO-cGMP pathway, as characteristically seen in migraine patients with and without aura. This indicates that the pathophysiological pathways underlying migraine headache in FHM-1 may be different from the common types of migraine.
ICHD-II Diagnostic Criteria for Tolosa—Hunt Syndrome in Idiopathic Inflammatory Syndromes of the Orbit and/or the Cavernous Sinus
Authors: Colnaghi S , Versino M , Marchioni E , Pichiecchio A , Bastianello S , Cosi V , Nappi G
Published: March 2008

A bibliographical search was conducted for papers published between 1999 and 2007 to verify the validity of International Classification of Headache Disorders (ICHD)-II criteria for the Tolosa-Hunt syndrome (THS) in terms of (i) the role of magnetic resonance imaging (MRI); (ii) which steroid treatment should be considered as adequate; and (iii) the response to treatment. Of 536 articles, 48, reporting on 62 patients, met the inclusion criteria. MRI was positive in 92.1% of the cases and it normalized after clinical resolution. There was no evidence of which steroid schedule should be considered as adequate; high-dose steroids are likely to be more effective both to induce resolution and to avoid recurrences. Pain subsided within the time limit required by the ICHD-II criteria, but signs did not. We conclude that THS diagnostic criteria can be improved on the basis of currently available data. MRI should play a pivotal role both to diagnose and to follow-up THS.
The Selendang Ayu Shipwreck and Oil Spill: Considering Threats and Fears of a Worst‐Case Scenario*
Authors: Ritchie Liesel A. , Gill Duane A.
Published: March 2008

On December 8, 2004, the Selendang Ayu, a Malaysian‐flagged freighter, ran aground off Unalaska Island in Alaska's Aleutian chain. Despite rescue efforts by the United States Coast Guard, six of the Selendang Ayu's crew members died. In addition to the deaths, more than 300,000 gallons of heavy bulk fuel oil spilled into the sea. Much of the oil washed onto the island's shores, into areas providing cultural, recreational, subsistence, and commercial fishing resources for residents of the renewable resource community of Dutch Harbor/Unalaska. The purpose of this article is to identify and examine different dimensions of risk, based on qualitative research conducted in 2005. We use a contextual constructionist approach to understand risk, which conceptualizes risk as an objective hazard, threat, or danger that is mediated through social and cultural processes. Research methods included 31 personal interviews, participatory observation, and a review of media coverage. Findings revealed several dimensions of risk perceived by residents: the incident in relation to Dutch Harbor/Unalaska as a high‐risk community and more general current events; threats to the community's annual $1 billion seafood industry; threats to Alaska Native subsistence culture; and issues of future risk and uncertainty. Interviews and observations support our conclusion that the Selendang Ayu incident represented a “shot across the bow” that could have been a “worst case” if oil had contaminated commercial fish processing. Residents believe that it is only a matter of time before another, more damaging accident occurs. Given this general perception, it is important to more clearly assess risk in Dutch Harbor/Unalaska and help the community increase resilience to the multiple hazards it faces. More broadly, Dutch Harbor/Unalaska serves as an example—all communities could benefit from better risk assessments and increased attention to resiliency.
NUTRITIONAL REQUIREMENTS OF HAEMATOCOCCUS PLUVZALIS AND RELATED SPECIES1
Authors: Pringsheim Ernest G.
Published: March 2008

All the described species and varieties of the genus Haematococcus were available. After isolation in pure culture they were used studying their nutritional requirements.

H. buetschlii and H. droebakensis had already been shown by Droop to need vitamin B12. H. capensis typ., H. capensis var. borealis, and H. zimbabwiensis were found to do so also. The 7 strains of H. pluvi‐alis from various localities investigated showed slight physiological deviations, although morphologically they were so similar that they should not be described as varieties.

A dilute inorganic nutrient solution with trace elements and iron kept in solution by EDTA was suitable either as such or supplemented with growth‐promoting compounds. The growth was speeded by low concentrations of acetate and by enhancing photosynthesis.

No strain of H. pluvialis absolutely required cobalamin, although it stimulated. Thiamine had a much more pronounced effect; for some strains it was indispensable. Although the response varies slightly from strain to strain, a luxuriant growth for all was obtained only with acetate and B1, and usually enhanced by B12. A peculiar feature of H. pluvialis is the catching up of cultures initially retarded by thiamine deficiency (probably due to slow Bl synthesis).

When H. pluvialis multiplied fast its appearance differed from that considered typical: no red pigment and the cell wall not inflated. In nature it evidently lives under conditions unfavorable for good growth although suitable for survival in competition with other organisms.
PHOTOINDUCTION AND PHOTOREVERSAL OF THE NOSTOCACEAN DEVELOPMENTAL CYCLE1
Authors: Lazaroff Norman
Published: March 2008

The developmental cycle of Nostoc muscorum, a nitrogen‐fixing blue‐green alga, is controlled by the spectral quality of illumination. Red light with peak activity at 650 mμ induces development of filaments from a nonfilamentous (aseriate) stage of the life cycle. Red‐light photoinduction is reversed by simultaneous or subsequent exposure to light from a broad band in the green region of the spectrum. Photoreversibility of the red‐light induction, by green light, decays very slowly, remaining at an appreciable level for over 24 hr after the primary stimulus.

Allophycocyanin is indicated to be the photoreceptor for red‐light induction. One or more phycoeythrins may operate as photoreceptors for reversal of induction.

The dosage response and wavelength dependence of developmental photocontrol in Nostoc muscorum A indicate that a nonphotosynthetic mechanism is involved in both developmental photoinduction and its photoreversal.
EFFECTS OF TEMPERATURE AND ILLUMINANCE ON CELL DIVISION RATES OF THREE SPECIES OF TROPICAL OCEANIC PHYTOPLANKTON1
Authors: Thomas William H.
Published: March 2008

Three species of tropical oceanic phytoplankton were isolated from two locations in the eastern Pacific Ocean. Unialgal cultures were maintained in an enriched seawater medium. The effects of temperature, and, in separate experiments, illuminance, on the exponential cell division rates of those algae were investigated. For 2 isolates of Gymnodinium sp. (probably G. simplex), maximum growth rates were 1.25 and 1.7 divisions/24 hr, the optimum temperature range was 23–29 C, the compensation illuminance was 35 ft‐c, and the saturation illuminance was 750 ft‐c and above. For a small species of Chaetoceros, the maximum growth rate was 6.0 divisions/24 hr, the optimum temperature range was 23–37 C, the compensation illuminance was 10 ft‐c, and the saturation illuminance was 600 ft‐c. For a small Nannochloris species, the maximum growth rate was 4.5 divisions/ 24 hr, the optimum temperature range was 27–37 C, and the saturation illuminance was 800 ft‐c. Nannochloris grew heterotrophically by apparently utilizing organic matter supplied by soil extract.
HETEROTROPHY OF FOUR MARINE PHYTOPLANKTERS AT LOW SUBSTRATE CONCENTRATIONS1
Authors: Sloan P. R. , Strickland J. D. H.
Published: March 2008

Three pelagic marine phytoplankters, Coccolithus huxleyi, Skeletonema costatum, and Thalassiosira rotula, and a facultative heterotroph, Cyclotella cryptica, have been exposed to three organic substrates, viz, glucose, acetate, and glutamate, at low concentrations (organic carbon 0.25 mg/liter). Experiments were performed in the dark and light and the net assimilation of substrate was measured by using radiocarbon. The dark uptake of carbon dioxide was also determined, together with photosynthesis at near optimum light intensity. The expected heterotrophy was detected with Cyclotella cryptica. Thalassiosira rotula was found to assimilate glutamate at an appreciable rate. In all cases, however, the short‐term uptake of carbon dioxide in the dark was the greatest assimilation rate measured. Values are discussed in relation to their ecological significance and it is concluded that heterotrophic survival of these and probably most other algae in the open ocean would be impossible unless they were in contact with a high concentration of substrate in the form of particulate matter.
PARASITISM OF ASTERIONELLA FORMOSA HASS. BY A CHYTRID IN TWO LAKES OF THE RAWAH WILD AREA OF COLORADO1
Authors: Koob Derry D.
Published: March 2008

The populations of Asterionella formosa Hass. in two subalpine lakes in the Rawah Wild Area, Colorado, were composed of colonies of five distinct size classes Based on frustule length. The spring bloom in these two lakes was dominated by cells of the Beta or Gamma population, whereas the fall pulse was dominated by cells of the Alpha and Beta, or Alpha populations. The Beta population was physiologically unique in that it was parasitized by the chytrid Rhizophidium planktonicum Canter. The development of the parasite population could not be correlated with the concentration or the growth phase of the host population. The occurrence of parasitism did not noticeably affect the population growth patterns of the Asterionella populations.
LOLA ZRREGULARIS (CHLOROPHYTA‐CLADOPHORACEAE): A NEW SPECIES FROM THE ROSS SEA, ANTARCTICA1
Authors: Zaneveld Jacques S.
Published: March 2008

A small, loose lying, unbranched, filamentous alga from the Ross Sea, Antarctica, is described as a new species, Lola irregularis. The genus Lola is closely related to the genera Hormiscia, Rhizoclonium, and Chaetomorpha in the family Cladophoraceae. A key to all known species of Lola is included. This is the first record of a species of Lola south of the Antarctic convergence.
GLUTAMINE SYNTHETASE ASE ACTYVITY IN IN CHAETOCEROS AFFINIS (BACILLARIOPHYCEAE): COMPARISON WITH OTHER ESTIMATES OF NITROGEN UTILIZATION DURING NUTRIENT PERTURBATION1
Authors: Slawyk Gerd , Rodier Martine
Published: March 2008

Glutamine synthftase (GS) activity was investigated in a nitratt limited continuous culture of the marine diatom Chaeloccros afTinis (Lauder) Hustedt before and after the perturbation of the culture medium with 10 μM of 15 N labelled nitrate. Parallel studies were carried out on nitrate reductase(NR). nitrate uptake and assimilation, and Ievels of cellular nitrogen containing compounds with the objective to determine the validity of the GS assay as a measure of nitrate utilization. Activities in N‐deficient cells, grown at steady state, correlated well with uptake and assimilation rates. In N‐sufftcient celts, however, during the nitrate pertirbation period, they accounted only for about 10% of the two latter rates, when ambient nitrate concentrations were high (0. 7‐10 μ). It is proposed that under these growth conditions an alternative pathway via glutamate dehydrogenase (GDH) was operative. At low ambient nitrate concentrations (0.1‐0.7 μM), GS activities, uptake and assimilation rates again balanced rather well. Thus, the data support the view that GDH activity is associated with high levels and GS with low levels of external or internal nitrogen.
PARAMYLONSYNTHESISAND CHLOROPLAST STRUCTURE ASSOCIATEED WITH NUTRIENTLEVELSINEuUGLENA(EUGLENOPHYCEAE)1
Authors: Kiss John Z. , Vasoconcelos Aurea C. , Triemer Richard E.
Published: March 2008

A System has been developed to study the photoheterotrophic synthesis of paramylon, a β‐1,3 glucan storage product found in the euglenoid flagellates. The amount of paramylon in the cells is controlled by manipulating the levels of nutrients in the culture medium. During experimental conditions, when cells are transferred from an incomplete to a complete medium, the transferred from an incomplete to a complete medium, the paramylon concentration increases at least seven‐fold relative to the controls. Electron microscopic studies demonstrate that the pyrenoid disperses concomitantly with the period of paramylon increase. The pyrenoid of Euglena is labeled by a ribulose‐1,5 bisphosphate carboxylase‐oxygenase(Ru‐BisCO)antibody. The distribution of ruBisCO in the clocrplast is directly related to pyrenoid dispersal.
EFFECTS OF TEMPERATURE, SALINITY, IRRADIANCE AND DIURNAL PERIODICITY ON GROWTH AND PHOTOSYNTHESIS IN THE DIATOM NITZSCHIA AMERICANA; LIGHT‐SATURATED GROWTH1
Authors: Miller Richard L. , Kamykowski Daniel L.
Published: March 2008

The physiological response of an estuarine clone of Nitzschia americana Fryx3ell was measured under experimental conditions of temperature and salinity which represent the average range of these variables in the Cape Fear River Estuary, North Carolina. The influence of temperature (10, 15, 20, 25, 30°C) and salinity (8, 15, 20, 26, 32‰) on specific growth rates, μ, and parameters of photosynthesis‐irradiance curves, α, and Pmax were measured during maximum and minimum rates of diurnal photosynthesis using axenic semi‐continuous batch cultures maintained at an irradiance saturating for photosynthesis (140 μE m‐2·s‐1). There was an increase in μ with increasing temperature up to a broad uptimum (25 ± 2.5°C), above which μ gradually declined. At the predicted optimum temperature of 25°C, μ increased as a linear function of salinity. oth light‐limited (α) amd light‐saturated (Pmax) rates of photosynthesis increased as salinity decreased. The effect of temperature on a and Pmax was complex and dependent on salinity. Pmax exhibited a diurnal periodicity, whereas estimates of a were not significantly different between sampling periods. Growth efficiencey opf N. americana, calculated as the ratio between specific growth rates and rates of gross photosynthesis, increased with an increase in salinity with a maximum at the predicted optimum temperature and salinity of 25°C and 32‰, suggesting and uncoupling between photosynthesis and growth at nonoptimum growth conditions.
FLAGELLAR DEVELOPMENT AND REGENERATION IN VOLVOX CARTERI (CHLOROPHYTA)1
Authors: Coggin Steven J. , Kochert Gary
Published: March 2008

The biflagellate somatic cells of Volvox carteri f. nagariensis lyengar exhibit an asymmetric pattern of flagellar development. Initiallt each somatic cell has two short (4 μm) flagella but after several hours one flagellum on each cell elongates unitl it reaches a length of 12 μm. Due to the regular arrangement of somatic cells in the Volvox spheroid it is apparent that the same flagellum on each somatic is the first to elongale. The asymmetric flagellar length is maintained for about 8 h after which the second flagellum on each somatic cell elongates. When the second flagellum attains the same length (12 μm) as the first flagellum, both flagella elongale at the same rate until reaching a final length of 22 μm.

Experimental removal of somatic cell flagella results in their regeneration. Somatis cells regenerate both flagella simultaneously and full length flagella are produced in about 2 h. The intial rate of flagellar regeneration is about ten times faster than the intial rate of flagllar growth in development. Cycloheximide, an inhibitor of protein synthesis, has no effect on the initial rate of flagellar regeneration but the flagella produced in the presence of the drug are half the length of flagella produced in its absence. Somatic cells are able to regenerate flagella up to the time of α and β tubulin, the major structural proteins of the flagellar axoneme, and other cellular proteins.
DIATOM MINERALIZATION OF SILICIC ACID. VIII. METABOLIC REQUIREMENTS AND THE TIMING OF PROTEIN SYNTHESIS1
Authors: Blank Gregory S. , Robinson Dale H. , Sullivan Cornelius W.
Published: March 2008

We have examined the influence of temperature, protein synthesis, and energy metabolism on the process of silicon biomineralization in synchronized cultures of the diatom Navicula saprophilia Lange‐Bertalot & Bonik (1976). Temperature effects on silicon polymerization were compared in vitro and in vivo. In vivo incorporation was very temperature dependent with a Q10 of 7.53. In contrast, the Q10 for in vitro polymerization was 1.42, indicating much lower temperature dependence. This difference in Q10 values suggests that in vivo polymerization involves more than autopolycondensation. Cycloheximide addition to synchronized cultures up to, but not later than one hour after the addition of silicic acid depressed total uptake, incorporation, but not pool size. Developing valves demonstrated morphological abnormalities with cycloheximide additions from 0 to 2 h following silicic acid addition. These data suggest that de nova proteins are required in biomineralization and that they are synthesized during or just after cytokinesis. Biomineralization is not coupled to energy derived directly from photosystem II or photosynthesis, since neither darkness nor DCMU had an effect on any aspect of silicification.
DUDRESNAYA PUERTORICENSIS SP. NOV. (DUMONTIACEAE, GIGARTINALES, RHODOPHYTA)1
Authors: Searles Richard B. , Ballantine David L.
Published: March 2008

A new species of Dudresnaya is described from Puerto Rico and Georgia. Gametophytes have cylindrical axes, exserted apical cells, rectangular to hexagonal crystals in the axial cells, ellipsoidal outer assimilatory cells, spermatangial mother cells which are terminal or subterminal cells of the subdichotomously branched outer assimilatory branches and auxiliary cells which are indistinguishable in appearance from adjacent, large, deeply staining cells of the auxiliary cell branch. Tetrasporophytes are unknown.
ON THE MALE CONCEPTACLES OF TWO TERETE SPECCIES OF GRACILARIA(RHODOPHYTA, GIGGARTINALES)FROM NORTH CAROLINA1
Authors: Reading Richard P. , Schneider Craig W.
Published: March 2008

Inspired by the description of the spermatangial conceptacles in Gracilaria blodgettii Harvey from the Asian Paacific as a continuum form the Textorii‐type of the Verruccosa‐type, a reinvestiagation of male plants of that species from North Carolina reveals unifform Textorii‐type con cepptacles. A male specimen of what has been called G. verrucosa (Hudson) Papenffuss i North Carolina does, however, shour a continuum between the two morphological types. Other ccharacteristics are given and questions are raised concerning the use of the specific epithet. G. blodgettii, in areas outside of the western Atlantic.
ANNUAL GERMINATION WINFOW IN OOSPORES OF NITELLA FURCATA (CHAROPHYCEAE)1
Authors: Sokol Roger C. , Stross Raymond G.
Published: March 2008

Oospores of Nitella furcata subsp. megacarpa (Allen emend. Wood) were collected from an oospore bank in the sediments of Lake George, New York. Incubated at constant temperatures, all or nearly all of the oospores germinated when exposed to a brief pulse of red light when the annual window of germinability was open. The window seems related to the annual cycle of sediment temperatures. It is open in spring and closes wit the onset of a secondary dormacncy in the summer. Oospores in storage follow a parallel path if held at 18°C, a summer equivalent temperature; the window remains open indefinitely if the oospores are held at 4°C. Attention is drawn to the similarity if the cyclic window of germinability in seeds of summer annuals and oospores of N. furcata.
COMPARATIVE STUDIES ON THE CELL WALLS OF SEXUAL AND ASEXUAL BANGIA ATROPURPUREA (RHODOPHYTA). II ELECTROPHORETIC PATTERNS OF POLYSACCHARIDES1
Authors: Cole Kathleen M. , Park Carol M. , Reid Philip E. , Sheath Robert G.
Published: March 2008

Cellulose acetate electrophoresis of the hot water soluble polysaccharide extracts from whole filaments, as well as base, mid and tip segments, of marine asexual and sexual Bangia atropurpurea (Roth) C. Ag. Yielded distinctive patterns which demonstrated that changes occur in the outer cell walls during sexual reproduction. Heterogeneity of the sulfated polysaccharide components isolated from outer cell walls was shown to be specifically related to sexual reproduction. Two components (Band I and II) were detected in extracts from tips of sexual filaments, whole only one (Band I) was present in the vegetative segments of all filaments and in asexual reproductive regions. The faster running component (Band II) was detected during the later stages of sexual development, prior to maturation.
POPULATION DYNAMICS OF THE SPORE‐FORMING DIATOM LEPTOCYLINDRUS DANICUS IN NARRAGANSETT BAY. RHODE ISLAND1
Authors: French Fred W. , Hargraves Paul E.
Published: March 2008

A field study to assess resting spore importance in long‐and short‐term population dynamics of Leptocylindrus danicus (Ehr.) Gran was carried out, based on the observation that germinating spores produce only vegelative cells of maximum diameter. From May through November 1978. L. danicus was present in lower Narragansett Bay, but resting spores were not found. May and June bioassays suggest that Bay water could not support sexuality (hence spore formation) in L. danicus during this period. Mean valve diameter decreased abruptly in early June. as did cell number. When mean valve diameter increased abruptly in August, with no resting spores seen, 70 additional clonal isolates showed that one clone had the “normal” sexual and spore‐forming life cycle while 69 clones had an “alternate” life cycle lacking sperm and spore formation. Valvar fine structure of the two types differed with respect to the presence or absence of a subcentral valvar pore, and a new subspecific taxon is here distinguished: variety apora. Examination of the early June data indicates the replacement of one population by another. Populations of L. danicus may be sporadically introduced into Narragansett Bay from Gulf Stream rings.