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Nanoparticulate hydroxyapatites (HAps) reproducing some of the subnanometre length scale intermolecular interactions characteristic of hard tissue have been prepared for nuclear magnetic resonance (NMR) structural elucidation. HAps were precipitated at physiological pH and temperature from dilute aqueous solutions, in the presence of acidic polysaccharides (chondroitin sulfate, dermatan sulfate, hyaluronic acid, dextran sulfate, polygalacturonic acid), and of hydrophilic poly aminoacids (poly-l-glutamate, poly-l-asparagine, poly-l-lysine). The HAp resembles that of bone with respect to its 31P NMR properties, broad reflections in X-ray powder diffraction, and the coexistence of an ordered crystalline core, surrounded by a less ordered surface containing water and hydrogen phosphate. 13C{31P} rotational echo double resonance (REDOR) NMR, which probes carbon−phosphorus proximities below ca. 1 nm, shows that all the HAps are molecular composites in which each biopolymer forms intimate intermolecular associations with mineral ions. REDOR effects between mineral phosphorus and ring carbons of the polysaccharides, and the side-chain terminal carboxylate and amide carbonyls of poly-l-glutamate and poly-l-asparagine, and the side chain carbons of poly-l-lysine, closely recapitulate those seen in native bone. Such model HAp−biopolymer composites will prove useful in studies of the role of biopolymers in biomineralization, and in high resolution biomineral structure elucidation.

Structural biominerals are inorganic/organic composites that exhibit remarkable mechanical properties. However, the structure–property relationships of even the simplest building unit—mineral single crystals containing embedded macromolecules—remain poorly understood. Here, by means of a model biomineral made from calcite single crystals containing glycine (0–7 mol%) or aspartic acid (0–4 mol%), we elucidate the origin of the superior hardness of biogenic calcite. We analysed lattice distortions in these model crystals by using X-ray diffraction and molecular dynamics simulations, and by means of solid-state nuclear magnetic resonance show that the amino acids are incorporated as individual molecules. We also demonstrate that nanoindentation hardness increased with amino acid content, reaching values equivalent to their biogenic counterparts. A dislocation pinning model reveals that the enhanced hardness is determined by the force required to cut covalent bonds in the molecules.

Pathomechanisms underlying vascular calcification biogenesis are still incompletely understood. Biomineral from human atherosclerotic intimal plaques; human, equine, and bovine medial vascular calcifications; and human and equine bone was released from collagenous organic matrix by sodium hydroxide/sodium hypochlorite digestion. Solid-state 13C NMR of intimal plaque mineral shows signals from cholesterol/cholesteryl esters and fatty acids. In contrast, in mineral from pure medial calcifications and bone mineral, fatty acid signals predominate. Refluxing (chloroform/methanol) intimal plaque calcifications removes the cholesterylic but not the fatty acyl signals. The lipid composition of this refluxed mineral now closely resembles that of the medial and bone mineral, which is unchanged by reflux. Thus, intimal and medial vascular calcifications and bone mineral have in common a pool of occluded mineral-entrained fatty acyl-rich lipids. This population of fatty acid may contain methyl-branched fatty acids, possibly representing lipoprotein particle remnants. Cell signaling and mechanistic parallels between physiological (orthotopic) and pathological (ectopic) calcification are also reflected thus in the NMR spectroscopic fingerprints of mineral-associated and mineral-entrained lipids. Additionally the atherosclerotic plaque mineral alone shows a significant independent pool of cholesterylic lipids. Colocalization of mineral and lipid may be coincidental, but it could also reflect an essential mechanistic component of biomineralization.

Ibliform barnacles are among the few invertebrate animals harnessing calcium phosphate to construct hard tissue. The 31P solid-state NMR (SSNMR) signal from the shell plates of Ibla cumingi(Iblidae) is broader than that of bone, and shifted by ca1 ppm to low frequency. 1H–31P heteronuclear correlation (HETCOR) experiments show a continuum of different phosphorus/phosphate atomic environments, close to hydrogen populations with resonance frequencies between ca10 and 20 ppm. Associated 1H and 31P chemical shifts argue the coexistence of weakly (high 31P frequency, low 1H frequency) to more strongly (lower 31P frequency, higher 1H frequency) hydrogen-bonded hydrogen phosphate-like molecular/ionic species. There is no resolved signal from discrete OH−ions. 13C SSNMR shows chitin, protein and other organic biomolecules but, unlike bone, there are no significant atomic scale organic matrix–mineral contacts. The poorly ordered hydrogen phosphate-like iblid mineral is strikingly different, structurally and compositionally, from both vertebrate bone mineral and the more crystalline fluoroapatite of the linguliform brachiopods. It probably represents a previously poorly characterized calcium phosphate biomineral, the evolution of which may have reflected either the chemical conditions of ancestral seas or the mechanical advantages of phosphatic biomineralization over a calcium carbonate equivalent.

Fein gemahlen: Auf mechanochemischem Weg wurden der Pharmaka‐Bestandteil Bismutsubsalicylat sowie Bismutdisalicylat und ‐trisalicylat direkt aus Bismutoxid hergestellt. Durch Röntgenpulverbeugung gelang die erste Strukturaufklärung eines Bismutsalicylats ohne organische Hilfsliganden (siehe Bild: Bi gelb, O rot, C grau; Salicylat‐Ionen in zwei Koordinationsmodi: rosa und grün).

Ground out: Mechanochemical methods gave the pharmaceutical ingredient bismuth subsalicylate, as well as bismuth disalicylate and trisalicylate directly from bismuth oxide. Structure determination by powder X‐ray diffraction gave the first structure of a bismuth salicylate without auxiliary organic ligands (see picture: Bi yellow, O red, C gray, two salicylate ion coordination modes are shown in purple and green).

Unusually for invertebrates, linguliform brachiopods employ calcium phosphate mineral in hard tissue formation, in common with the evolutionarily distant vertebrates. Using solid-state nuclear magnetic resonance spectroscopy (SSNMR) and X-ray powder diffraction, we compare the organic constitution, crystallinity and organic matrix–mineral interface of phosphatic brachiopod shells with those of vertebrate bone. In particular, the organic–mineral interfaces crucial for the stability and properties of biomineral were probed with SSNMR rotational echo double resonance (REDOR). Lingula anatinaand Discinisca tenuisshell materials yield strikingly dissimilar SSNMR spectra, arguing for quite different organic constitutions. However, their fluoroapatite-like mineral is highly crystalline, unlike the poorly ordered hydroxyapatite of bone. Neither shell material shows 13C{31P} REDOR effects, excluding strong physico-chemical interactions between mineral and organic matrix, unlike bone in which glycosaminoglycans and proteins are composited with mineral at sub-nanometre length scales. Differences between organic matrix of shell material from L. anatinaand D. tenuis, and bone reflect evolutionary pressures from contrasting habitats and structural purposes. The absence of organic–mineral intermolecular associations in brachiopod shell argues that biomineralization follows different mechanistic pathways to bone; their details hold clues to the molecular structural evolution of phosphatic biominerals, and may provide insights into novel composite design.

Eine Prise Salz: Kleine Salzmengen beschleunigen und steuern den mechanochemischen Aufbau Metall‐organischer Gerüste (MOFs) aus einem Metalloxid (siehe Schema; ILAG= ionen‐ und flüssigkeitsunterstütztes Mahlen). Dieses Raumtemperaturverfahren belegt, dass die Mechanosynthese von Metall‐organischen Verbindungen mit Templaten gesteuert werden kann und dass es durch Mechanochemie möglich ist, ionische Gäste in neutrale MOFs einzuschließen.

We have studied the atomic level structure of mineralized articular cartilage with heteronuclear solid-state NMR, our aims being to identify the inorganic species present at the surfaces of the mineral crystals which may interact with the surrounding organic matrix and to determine which components of the organic matrix are most closely involved with the mineral crystals. One-dimensional 1H and 31P and two-dimensional 1H-31P heteronuclear correlation NMR experiments show that the mineral component is very similar to that in bone with regard to its surface structure. 13C{31P} rotational echo double resonance experiments identify the organic molecules at the mineral surface as glycosaminoglycans, which concurs with our recent finding in bone. There is also evidence of γ-carboxyglutamic acid residues interacting with the mineral. However, other matrix components appear more distant from the mineral compared with bone. This may be due to a larger hydration layer on the mineral crystal surfaces in calcified cartilage.

The 19F NMR signal half‐height linewidths of six fluorinated psychiatric pharmaceuticals, on which successful in vivo magnetic resonance (MR) studies have been reported (fenfluramine, fluvoxamine, fluoxetine, trifluoperazine, phenfluramine, and paroxetine), were measured at 0.3 mM concentration in an artificial biofluid consisting of aqueous isotonic neutral phosphate‐buffered saline and 5% w/v bovine serum albumin. For the first five, which contain trifluoromethyl groups, linewidth is strongly positively correlated (R2=0.95) with calculated water: n‐octanol distribution coefficient at pH7 (cLogDpH7) by the relationship: Linewidth (Hz)=38cLogDpH7+5. This suggests that simple measurements, or calculations, feasible in most chemical laboratories, predict in vivo signal linewidth and hence the likely ease with which a development compound would be detected in clinical trials of brain pharmacokinetics. The procedures are available to all drug development organizations and should help establish confidence, or no‐go decisions, about committing major resources to MR pharmacokinetic studies on human subjects. Drug Dev Res 69:279–283, 2008  © 2008 Wiley‐Liss, Inc.

Killer whale (Orcinus orca) encounters from commercial pelagic trawlers as well as other types of vessels have been documented in several regions of the northeast Atlantic; however, very little published information is available regarding such encounters in mackerel (Scomber scombrus) and herring (Clupea harengus) fisheries, in the waters between northern Scotland and Norway. Mackerel and herring are the two main fish species targeted by the Scottish pelagic fleet, primarily during October to March and June to September, respectively. Encounters with killer whales were recorded during January and February 2006 by observers on a pelagic trawler fishing for mackerel in this area. These recent data, along with historical records collected since 2000, demonstrate the existence of frequent encounters between commercial pelagic trawlers and killer whales. We describe the foraging behaviour displayed by the whales during fishing operations. Killer whales approached the vessels during retrieval of the net, and remained there until this was completed. They were sometimes sighted during steaming and towing, although there was no observed contact with the boat or net at these times. There is no evidence that the presence of killer whales reduced the amount of fish caught by the trawlers or that killer whales ever become entangled in the nets. We suggest that, during the mackerel fishing season, the whales may obtain a significant proportion of their daily energy requirements from this source.

High-resolution, non-invasive imaging methods are required to monitor progression and regression of atherosclerotic plaques. We investigated the use of MRI to measure changes in plaque volume and vessel remodelling during progression and regression of atherosclerosis in New Zealand White rabbits. Atherosclerotic lesions were induced in the abdominal aorta by balloon injury and cholesterol feeding. MR images (2D) of the abdominal aorta were acquired with cardiac and respiratory gating using a fast spin echo sequence with and without fat-suppression. In an initial study on rabbits treated for 30 weeks we imaged the aortae with a spatial resolution of 250×250 micrometers with a slice thickness of 2 mm and achieved a close correlation between MRI-derived measurements and those made on perfusion pressure-fixed histological sections (r1= 0.83, slope p1< 0.01). We subsequently imaged 18 rabbits before and periodically during 12 weeks of cholesterol feeding (progression) followed by 12 weeks on normal diet (regression). Aortic wall (atherosclerotic lesion) volume increased significantly during progression and decreased during regression. In contrast, lumen volume increased during progression and did not change during regression. In conclusion, this study confirms that non-invasive, high-resolution MRI can be used to monitor progression and regression of atherosclerosis, each within 3 months and shows, for the first time in a short-term model, that positive remodelling occurs early during progression and persists through regression of atherosclerotic lesions.

Several analytical methods are available for determining the partition coefficients of drug compounds in model phospholipid membranes, but such methods provide little information at the molecular level about how the membrane affinity of drugs relates to their interactions with the lipid molecules. A new 2H nuclear magnetic resonance (NMR) approach has been developed here that quantifies the affinity of 2H-labeled small molecules for different phospholipid membranes and, simultaneously, provides information on the mechanism of the drug–membrane interaction. In the example given, 2H NMR analysis of a weakly basic ion pump inhibitor found that the drug partitioned preferentially into membranes of predominantly unsaturated or short-chain phospholipids. The 2H NMR analysis also suggested that the membrane specificity of the drug was directly correlated to the ability of its phenyl moiety to penetrate into the interior of the lipid bilayer. The 2H NMR approach could be of value in guiding medicinal chemistry toward or away from structures promoting interactions with specific types of biological membranes. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:507–514, 2004

Several analytical methods are available for determining the partition coefficients of drug compounds in model phospholipid membranes, but such methods provide little information at the molecular level about how the membrane affinity of drugs relates to their interactions with the lipid molecules. A new ²H nuclear magnetic resonance (NMR) approach has been developed here that quantifies the affinity of ²H-labeled small molecules for different phospholipid membranes and, simultaneously, provides information on the mechanism of the drug–membrane interaction. In the example given, ²H NMR analysis of a weakly basic ion pump inhibitor found that the drug partitioned preferentially into membranes of predominantly unsaturated or short-chain phospholipids. The ²H NMR analysis also suggested that the membrane specificity of the drug was directly correlated to the ability of its phenyl moiety to penetrate into the interior of the lipid bilayer. The ²H NMR approach could be of value in guiding medicinal chemistry toward or away from structures promoting interactions with specific types of biological membranes. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:507–514, 2004

Magnetic resonance images have been acquired during reversed-phase liquid chromatography of retained gadolinium chelates. The images can be used to distinguish between columns showing high and low isocratic plate counts and to locate the source of poor performance. Images can be displayed as longitudinal or transverse 2-D plots, as 3-D “movies”, or can be manipulated to visualise the analytes' trajectories as a function of time. Such trajectories provide qualitative confirmation of gradient chromatography theory. MRI is a tool with potential to enable targeted improvements in column manufacture and to inform theoretical studies.

This study investigates whether pelagic fish schools of different species or groupings (e.g. herring, "surface herring", "gadoids", mackerel, sprat and sandeels) were positively or negatively associated with each other in time and space. To do this, statistical models were fitted to pre-processed acoustic fisheries data to reveal how pelagic school prevalence varied with respect to spatial (latitude and longitude) and temporal (time of day) information. The model outputs, which take the form of probabilities fitted to the presence or absence of schools, were then used to calculate correlation coefficients, which are useful for measuring association between pairs of variables. Results depended upon the specific species pairs under investigation. Herring and "surface herring" were, for example, very generally sympatrically associated with each other in both space and time, while herring and gadoid schools, on the other hand, had allopatric distributions.

This study investigates whether pelagic fish schools of different species or groupings (e.g. herring, "surface herring", "gadoids", mackerel, sprat and sandeels) were positively or negatively associated with each other in time and space. To do this, statistical models were fitted to pre-processed acoustic fisheries data to reveal how pelagic school prevalence varied with respect to spatial (latitude and longitude) and temporal (time of day) information. The model outputs, which take the form of probabilities fitted to the presence or absence of schools, were then used to calculate correlation coefficients, which are useful for measuring association between pairs of variables. Results depended upon the specific species pairs under investigation. Herring and "surface herring" were, for example, very generally sympatrically associated with each other in both space and time, while herring and gadoid schools, on the other hand, had allopatric distributions.

We have used high-resolution three-dimensional magnetic resonance imaging (MRI) to measure the surface area, volume, and length of the nasal cavities of cynomolgus monkeys (10 male, six female) over a range of body weights (1.9-5.3 kg, mean 2.9 kg) and ages (8-45 months, mean 30.0 months). The measurements were carried out ex vivo on formalin-fixed, decalcified nasal cavities filled with water. Mean (standard deviation) values were 30.2 (7.2) cm2, 2.33 (0.65) cm3, and 3.34 (0.44) cm, respectively. Linear regression least squares best fits provide the following empirical relationships:Nasal cavity surface area (SA, cm2) as a function of body weight (BW, kg):SA = 15.1 + 5.1(BW), R = 0.84Nasal cavity volume (V, cm3) as a function of body weight:V = 1.15 + 0.4(BW), R = 0.74Nasal cavity length (L, cm) as a function of body weight:L = 2.43 + 0.31(BW), R = 0.84The left and right sides of the cavity were symmetrical in both males and females and showed little anatomical variation between individuals. The perimeter of the nasal cavity was maximal at about 60% of its extent from the nares. These data can aid in extrapolating nasal dosimetric exposure indices from cynomolgus monkeys (1.9-5.3 kg) to other species.

Littoraria ianthostoma, n. sp. is described from mangrove forests in Joseph Bonaparte Gulf in northwestern Australia. The new species superficially resembles the widespread Littoraria articulata (Philippi, 1846), with which it is sympatric, but differs in the closed penial sperm duct and absence of a pseudotrich in the paraspermatozoa. Allozyme analysis confirms a large genetic distance between these two species and fixed allelic differences between sympatric samples. This discovery is surprising because the distribution and taxonomy of the mangrove-associated Littoraria of Australia had been considered well known. The anatomy and protoconch indicate that the new species produces pelagic egg capsules and undergoes planktotrophic development. Nevertheless, it has not been found outside Joseph Bonaparte Gulf and so appears to be the most narrowly distributed of the 39 members of the genus. Possible phylogenetic relationships of the new species and apparent isolation of Joseph Bonaparte Gulf are discussed.

Ischaemic preconditioning in rats was studied using MRI. Ischaemic preconditioning was induced, using an intraluminal filament method, by 30 min middle cerebral artery occlusion (MCAO), and imaged 24 h later. The secondary insult of 100 min MCAO was induced 3 days following preconditioning and imaged 24 and 72 h later. Twenty‐four hours following ischaemic preconditioning most rats showed small sub‐cortical hyperintense regions not seen in sham‐preconditioned rats. Twenty‐four hours and 72 h following the secondary insult preconditioned animals showed significantly smaller lesions (24 h = 112 ± 31 mm3, mean ± standard error; 72 h = 80 ± 35 mm3), which were confined to the striatum, than controls (24 h = 234 ± 32 mm3, p= 0.026; 72 h = 275 ± 37 mm3, p= 0.003). In addition during lesion maturation from 24 to 72 h post‐secondary MCAO, preconditioned rats displayed an average reduction in lesion size as measured by MRI whereas sham‐preconditioned rats displayed increases in lesion size; this is the first report of such differential lesion volume evolution in cerebral ischaemic preconditioning. Copyright ­© 2001 John Wiley & Sons, Ltd.

Ischaemic preconditioning in rats was studied using MRI. Ischaemic preconditioning was induced, using an intraluminal filament method, by 30 min middle cerebral artery occlusion (MCAO), and imaged 24 h later. The secondary insult of 100 min MCAO was induced 3 days following preconditioning and imaged 24 and 72 h later. Twenty-four hours following ischaemic preconditioning most rats showed small sub-cortical hyperintense regions not seen in sham-preconditioned rats. Twenty-four hours and 72 h following the secondary insult preconditioned animals showed significantly smaller lesions (24 h = 112 ± 31 mm³, mean ± standard error; 72 h = 80 ± 35 mm³), which were confined to the striatum, than controls (24 h = 234 ± 32 mm³, p = 0.026; 72 h = 275 ± 37 mm³, p = 0.003). In addition during lesion maturation from 24 to 72 h post-secondary MCAO, preconditioned rats displayed an average reduction in lesion size as measured by MRI whereas sham-preconditioned rats displayed increases in lesion size; this is the first report of such differential lesion volume evolution in cerebral ischaemic preconditioning. Copyright ­© 2001 John Wiley & Sons, Ltd. Abbreviations used: IL-1b interleukin-1b MCAO middle cerebral artery occlusion MRI magnetic resonance imaging NBF neutral bufferred formalin RARE rapid acquisition with relaxation enhancement T2W T2 weighted TE echo time TR repetition time.

The geographical distribution of the limpet family Patellidae is essentially antitropical, with 18 species in southern Africa, 10 in the northeastern Atlantic, and only 11 species elsewhere (although 4 of these do occur in the tropics). One possible explanation for this distribution is the suggestion of a recent, perhaps Early Pliocene, migration from southern Africa northward. We tested this hypothesis by constructing a molecular phylogeny, derived from partial sequences of the 12S and 16S mitochondrial genes, obtained from 34 of the 38 patellid species. Five species of Nacellidae and 3 of Lottiidae were included as potential outgroups. Analysis revealed that two patellid clades are represented in the northeastern Atlantic. The typical European patellids (Patella sensu stricto) form a single clade within which there is little molecular divergence, but are distant from all other patellids, thus refuting the idea of recent southern ancestry. From the limited fossil record and estimated rates of molecular divergence, we suggest thatPatella s.s.may have originated at least as early as the Upper Cretaceous and that its northern distribution may have been achieved at the same time. The second patellid clade present in the northeastern Atlantic is the genusCymbula,of which the single speciesCymbula safianaextends from West Africa to the Mediterranean. In contrast toPatella s.s., C. safianais indeed a member of an otherwise southern African clade and may have attained its present distribution more recently, during the Miocene. The geographical origin of the family remains unclear, but a Mesozoic radiation in southern Gondwana is possible. By optimizing morphological characters on our molecular tree, we consider the evolution of shell mineralogy and sperm ultrastructure. We also discuss the phylogenetic classification of the patellids and present some evidence that the family may not be monophyletic.

An examination of the shell microstructure and mineralogy of species from 30 of the 32 genera and subgenera of the gastropod family Littorinidae shows that most species have a shell consisting of layers of aragonitic crossed-lamellar structure, with minor variations in some taxa. However, Pellilitorina, Risellopsis and most species of Littorina have partly or entirely calcitic shells. In Pellilitorina the shell is made entirely of calcitic crossed-foliated structure, while in the other two genera there is only an outer calcitic layer of irregular-prismatic structure. A cladistic analysis shows that the calcitic layers have been independently evolved in at least three clades. The calcite is found only in the outermost layers of the shell and in species inhabiting cooler waters of both northern and southern hemispheres. Calcium carbonate is more soluble in cold than warm water and, of the two polymorphs, calcite is about 35% less soluble than aragonite. We suggest that calcitic shell layers are an adaptation of high latitude littorinids to resist shell dissolution.

Substituted imidazo[1,2‐a]pyridines are pharmaceutically important small molecule inhibitors of the gastric H+/K+‐ATPase, the membrane‐bound therapeutic target for peptic ulcer disease. A non‐perturbing analytical technique, rotational resonance NMR spectroscopy, was used to measure a precise (to ±0.2 Å) distance between atomic sites in a substituted imidazo[1,2‐a]pyridine, TMPIP, bound to H+/K+‐ATPase at its high‐affinity site in the intact, native membrane. The structural analysis of the enzyme–inhibitor complex revealed that the flexible moiety of TMPIP adopts a ‘syn‐type’ conformation at its site of action. Hence, the conformation of an inhibitor has been resolved directly under near‐physiological conditions, providing a sound experimental basis for rational design of many active compounds of pharmaceutical interest. Chemically restraining the flexible moiety of compounds like TMPIP in the syn‐type binding conformation was found to increase activity by over 2 orders of magnitude. Such information is normally only available after extensive synthesis of related compounds and multiple screening approaches.

Magic‐angle spinning (MAS) has recently been shown to enhance spectral resolution in NMR examinations of intact biological tissue ex vivo. This work demonstrates that freezing certain tissue samples before examination by 1H MAS NMR can have a marked effect on their spectra. Spectra of rat kidney after freezing in liquid nitrogen, compared with spectra before freezing, showed a significant increase in signal intensities from alanine (>100%), glutamine (>40%), and glycine (>100%), and a decrease in signals assigned to lipids and other macromolecules. Some resonances‐such as from leucine, valine, isoleucine, and aspartate‐only became visible after freezing the tissue. These observations suggest that low temperature storage of tissue necropsies or biopsies might affect the results of a MAS NMR analysis, possibly resulting in the misinterpretation of metabolite changes to pathogen or disease effects.

Abstract.: In the past, 18S rRNA sequences have proved to be very useful for tracing ancient divergences but were rarely used for resolving more recent ones. Moreover, it was suggested that the molecule does not contain useful information to resolve divergences which took place during less than 40 Myr. The present paper takes littorinid phylogeny as a case study to reevaluate the utility of the molecule for resolving recent divergences. Two data sets for nine species of the snail family Littorinidae were analyzed, both separately and combined. One data set comprised 7 new complete 18S rRNA sequences aligned with 2 published littorinid sequences; the other comprised 12 morphological, 1 biochemical, and 2 18S rRNA secondary structure characters. On the basis of its ability to confirm generally accepted relationships and the congruence of results derived from the different data sets, it is concluded that 18S rRNA sequences do contain information to resolve ``rapid'' cladogenetic events, provided that they occurred in the not too distant past. 18S rRNA sequences yielded support for (1) the branching order (L. littorea, (L. obtusata, (L. saxatilis, L. compressa))) and (2) the basal position of L. striata in the Littorina clade.

The characteristics of mackerel schools are described from the results of an acoustic survey carried out in January 1994. Schools were typically found in midwater, over bottom depths of >100m to just beyond the shelf break. They were of deep vertical spread (up to 105m) with a mean estimated width of 200m, with packing densities of up to 9 fish m−3and a mean biomass of 640 tonnes. Schools were aggregated into discrete patches of high biomass (up to 12000 tonnes) which were confined to relatively small areas and separated by distances of up to 50 miles. With this type of distribution it is possible to make repeated surveys over aggregations to determine direction and speed of migration. Spatial distribution from the acoustic survey was compared to that of the main commercial fleet to evaluate how well the latter reflected the distribution and migration of the stock. Using the fleet data, estimated migration rates were 13.0cm s−1, 17.8cm s−1and 25.9cm s−1for the months of December, January, and February, respectively. The distribution of catches in January 1994 was compared with that of previous years and showed no reversal of the northward shift of recent years. The relationship between sea temperature, salinity conditions, shelf edge current measurements, and the distribution of schools is described for the first time.

Gross anatomical characters of all 18 species of Littorina are used to construct a phylogenetic hypothesis for the genus, by the method of cladistic analysis. The resulting cladogram suggests that of the four subgenera of Littorina, one (Littorina) is paraphyletic. It is uncertain whether the genus Mainwaringia should be included in Littorina. It is shown that the non-planktotrophic Littorina species in the northern Atlantic comprise a monophyletic group, with the sister-species L. kurila and/or L. subrotundata in the northern Pacific. Invasion of the Atlantic by a minimum of two Pacific species, across the Arctic migration route established during the late Cenozoic, is sufficient to account for the modern distribution of the subgenera Littorina and Neritrema. The importance of the cladogram as a basis for hypotheses of adaptation is illustrated by a discussion of spawn and development in Littorina.

□ Proton decoupled, cross-polarization magic-angle spinning 13C NMR spectra of four polymorphic forms (A, B, C, and D) and a monohydrate form (M1) of the histamine H2antagonist cimetidine were obtained, and the chemical shifts of the various forms were tabulated. A modified polarization inversion pulse sequence was used to distinguish quaternary, methine, methylene, and methyl carbon resonances and thereby assist spectral assignment. It is also shown that the solid-state form of cimetidine in a commercial formulation can be reliably ascertained by NMR, despite the presence in the spectrum of signals from organic excipients that are much more intense than those from the compound.

Proton decoupled, cross-polarization magic-angle spinning ¹³C NMR spectra of four polymorphic forms (A, B, C, and D) and a monohydrate form (M1) of the histamine H2 antagonist cimetidine were obtained, and the chemical shifts of the various forms were tabulated. A modified polarization inversion pulse sequence was used to distinguish quaternary, methine, methylene, and methyl carbon resonances and thereby assist spectral assignment. It is also shown that the solid-state form of cimetidine in a commercial formulation can be reliably ascertained by NMR, despite the presence in the spectrum of signals from organic excipients that are much more intense than those from the compound.