Lost in translation – a history of systematic confusion and comments on the type species of Squalodon and Patriocetus (Cetacea,Odontoceti)

Abstract: The two odontocete taxa Squalodon grateloupii and Patriocetus ehrlichii, both the type species of their respective genera, have been at the centre of a great deal of taxonomic confusion. Originally regarded to be conspecific, these two taxa have been the subject of a bewildering taxonomic debate lasting for more than a century, which recently led to the suggestion to abandon these widely used names and replace S. grateloupii with the similar, yet independently and later proposed name S. gratelupi as the type species of Squalodon. Here, we attempt to summarise the events leading to the current confused situation in the hope of resolving this issue once and for all and argue that the name Squalodon grateloupii, as originally proposed, should be reinstated.     

Studies on geranylgeranyl diphosphate synthase from rat liver: specific inhibition by 3-azageranylgeranyl diphosphate.

Geranylgeranyl diphosphate synthase from rat liver was separated from farnesyl diphosphate synthase, the most abundant and widely occurring prenyltransferase, by DEAE-Toyopearl column chromatography. The enzyme catalyzed the formation of E,E,E-geranylgeranyl diphosphate (V) from isopentenyl diphosphate (II) and dimethylallyl diphosphate (I), geranyl diphosphate (III), or farnesyl diphosphate (IV) with relative velocities of 0.09:0.15:1. 3-Azageranylgeranyl diphosphate (VII), designed as a transition-state analog for the geranylgeranyl diphosphate synthase reaction, was synthesized and found to act as a specific inhibitor for this synthase, but not for farnesyl diphosphate synthase. Diphosphate V and its Z,E,E-isomer (VI) also inhibited geranylgeranyl diphosphate synthase, but the effect was not as striking as that of the aza analog VII. Specific inhibition of geranylgeranyl diphosphate synthase by VII was also observed in experiments with 100,000g supernatants of rat brain and liver homogenates which contained isopentenyl diphosphate isomerase and prenyltransferases including farnesyl diphosphate synthase as well as geranylgeranyl diphosphate synthase. For farnesyl:protein transferase from rat brain, however, the aza compound did not show a stronger inhibitory effect than E,E,E-geranylgeranyl diphosphate.     

Biosynthesis of monoterpenes: inhibition of (+)-pinene and (-)-pinene cyclases by thia and aza analogs of the 4R- and 4S-alpha-terpinyl carbocation.

(+)-Pinene cyclase (synthase) from Salvia officinalis leaf catalyzes the cyclization of geranyl pyrophosphate, via (3R)-linalyl pyrophosphate and the (4R)-alpha-terpinyl cation, to (+)-alpha-pinene and to lesser quantities of stereochemically related monoterpene olefins, whereas (-)-pinene cyclase converts the same achiral precursor, via (3S)-linalyl pyrophosphate and the (4S)-alpha-terpinyl cation, to (-)-alpha-pinene and (-)-beta-pinene and to lesser amounts of related olefins. Racemic thia analogs of the linalyl and alpha-terpinyl carbocation intermediates of the reaction sequence were previously shown to be good uncompetitive inhibitors of monoterpene cyclases, and inhibition was synergized by the presence of inorganic pyrophosphate. These results suggested that the normal reaction proceeds through a series of carbocation:pyrophosphate anion paired intermediates. Both the (4R)- and the (4S)-thia and -aza analogs of the alpha-terpinyl cation were prepared and tested as inhibitors with the antipodal pinene cyclases, both in the absence and in the presence of inorganic pyrophosphate. Although the inhibition kinetics were complex, cooperative binding of the analogs and inorganic pyrophosphate was demonstrated, consistent with ion pairing of intermediates in the course of the normal reaction. Based on the antipodal reactions catalyzed by the pinene cyclases, stereochemical differentiation between the (4R)- and the (4S)-analogs was anticipated; however, neither enzyme effectively distinguished between enantiomers of the thia and aza analogs of the alpha-terpinyl carbocation. Enantioselectivity in the enzymatic conversion of (RS)-alpha-terpinyl pyrophosphate to limonene by the pinene cyclases was also examined. Consistent with the results obtained with the thia and aza analogs, the pinene cyclases were unable to discriminate between enantiomers of alpha-terpinyl pyrophosphate in this unusual reaction. Either the alpha-terpinyl antipodes are too similar to allow differentiation by the pinene cyclases, or these enzymes lack an inherent requirement to distinguish the (4R)- and (4S)-forms because they encounter only one enantiomer in the course of the normal reaction from geranyl pyrophosphate.     

Angiotensin binding to rat adrenal capsular cell suspensions

Adrenal cell suspensions obtained by collagenase digestion of rat adrenal capsules was demonstrated to bind tritiated angiotensin II. The binding was rapid and reversible and was temperature dependent. Saturation of binding sites of a low order of capacity could be demonstrated by the addition of unlabeled angiotensin II. Specificity for this binding was demonstrated using several peptide analogues. Specificity was also observed with respect to cell type. These studies suggest the presence of a biologically significant receptor for angiotensin in cells of the zona glomerulosa of rat adrenal glands.     

Cholesteryl ester and triglyceride hydrolysis by an acid lipase from rabbit aorta.

The properties of the triglyceride- and cholesteryl ester-hydrolyzing activity by an acid lipase from rabbit aortic tissue were compared under different experimental conditions. Radiolabeled cholesteryl oleate or triolein was incorporated into phospholipid vesicles by sonication and the resulting preparations were used for in vitro studies. No distinction was observed between triglyceride lipase and cholesterol esterase activity in the aortic cytosol fraction following either thermal inactivation, inhibition by a mercurial, fractionation by ammonium sulfate or acid precipitation, or DEAE-cellulose chromatography. Addition of rabbit lipoproteins to the assay system resulted in inhibition of both cholesterol esterase and triglyceride lipase activity. Parallel changes in the hydrolysis of both substrates also were observed when exogenously added lipids were added to the incubation system in various physical states. Specificities of the enzyme system towards different cholesteryl esters were examined. No differences in the rate of hydrolysis were observed between cholesteryl oleate, palmitate and linoleate. The data suggest that a single acid lipase, presumably of lysosomal origin, has broad specificity towards triglycerides and cholesteryl esters, and may play a role in the hydrolysis of these lipids during intralysosomal degradation of lipoproteins.     

A thermodynamic study of mesophilic, thermophilic, and hyperthermophilic L-arabinose isomerases: the effects of divalent metal ions on protein stability at elevated temperatures

To gain insight into the structural stability of homologous homo-tetrameric l-arabinose isomerases (AI), we have examined the isothermal guanidine hydrochloride (GdnHCl)-induced unfolding of AIs from mesophilic Bacillus halodurans (BHAI), thermophilic Geobacillus stearothermophilus (GSAI), and hyperthermophilic Thermotoga maritima (TMAI) using circular dichroism spectroscopy. The GdnHCl-induced unfolding of the AIs can be well described by a two-state reaction between native tetramers and unfolded monomers, which directly confirms the validity of the linear extrapolation method to obtain the intrinsic stabilities of these proteins. The resulting unfolding free energy (DeltaGU) values of the AIs as a function of temperature were fit to the Gibbs-Helmholtz equation to determine their thermodynamic parameters based on a two-state mechanism. Compared with the stability curves of BHAI in the presence and absence of Mn2+, those of holo GSAI and TMAI were more broadened than those of the apo enzymes at all temperatures, indicating increased melting temperatures (Tm) due to decreased heat capacity (DeltaGp). Moreover, the extent of difference in DeltaCp between the apo and holo thermophilic AIs is larger than that of BHAI. From these studies, we suggest that the metal dependence of the thermophilic AIs, resulting in the reduced DeltaCp, may play a significant role in structural stability compared to their mesophilic analogues, and that the extent of metal dependence of AI stability seems to be highly correlated to oligomerization.     

Simple one-step purification of nisin Z from unclarified culture broth of Lactococcus lactis subsp. lactis A164 using expanded bed ion exchange chromatography

A simple one-step purification method, using expanded bed, ion-exchange chromatography, for the fractionation of nisin Z produced by Lactococcus lactis subsp. lactis A164 was developed. The highest dynamic binding capacity (0.92) of the adsorbent was obtained at a superficial velocity of 367 cm h(-1), resulting in approx. 2.7-fold bed expansion. The range of pH for the maximum adsorption was 3-4. The isocratic elution with 0.15 M NaCl led to approx. >90% recovery. Single-step purification of nisin Z from unclarified A164 culture broth resulted in 31-fold purification with a 90% yield.     

Anti-inflammatory effects of Stephania tetrandra S. Moore on interleukin-6 production and experimental inflammatory disease models

Deregulation of interleukin-6 (IL-6) expression caused the synthesis and release of many inflammatory mediators. It is involved in chronic inflammation, autoimmune diseases, and malignancy. Stephania tetrandra S. Moore is a Chinese medicinal herb which has been used traditionary as a remedy for neuralgia and arthritis in China. To investigate the anti-inflammatory effects of S. tetrandra S. Moore in vitro and in vivo, its effects on the production of IL-6 and inflammatory mediators were analysed. When human monocytes/macrophages stimulated with silica were treated with 0.1-10 mug/ml S. tetranda S. Moore, the production of IL-6 was inhibited up to 50%. At these concentrations, it had no cytotoxicity effect on these cells. It also suppressed the production of IL-6 by alveolar macrophages stimulated with silica. In addition, it inhibited the release of superoxide anion and hydrogen peroxide from human monocytes/macrophages. To assess the anti-fibrosis effects of S. tetrandra S. Moore, its effects on in vivo experimental inflammatory models were evaluated. In the experimental silicosis model, IL-6 activities in the sera and in the culture supernatants of pulmonary fibroblasts were also inhibited by it. In vitro and in vivo treatment of S. tetrandra S. Moore reduced collagen production by rat lung fibroblasts and lung tissue. Also, S. tetrandra S. Moore reduced the levels of serum GOT and GPT in the rat cirrhosis model induced by CCL(4), and it was effective in reducing hepatic fibrosis and nodular formation. Taken together, these data indicate that it has a potent anti-inflammatory and antifibrosis effect by reducing IL-6 production.