26Al/10Be Burial Dating of Xujiayao-Houjiayao Site in Nihewan Basin,Northern China

The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years). This paper reports the application of ²⁶Al/¹⁰Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ). The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site’s lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL) dating at 160–220 ka.     

Inhibition of Inactive States of Tetrodotoxin-Sensitive Sodium Channels Reduces Spontaneous Firing of C-Fiber Nociceptors and Produces Analgesia in Formalin and Complete Freund’s Adjuvant Models of Pain

While genetic evidence shows that the Nav1.7 voltage-gated sodium ion channel is a key regulator of pain, it is unclear exactly how Nav1.7 governs neuronal firing and what biophysical, physiological, and distribution properties of a pharmacological Nav1.7 inhibitor are required to produce analgesia. Here we characterize a series of aminotriazine inhibitors of Nav1.7 in vitro and in rodent models of pain and test the effects of the previously reported “compound 52” aminotriazine inhibitor on the spiking properties of nociceptors in vivo. Multiple aminotriazines, including some with low terminal brain to plasma concentration ratios, showed analgesic efficacy in the formalin model of pain. Effective concentrations were consistent with the in vitro potency as measured on partially-inactivated Nav1.7 but were far below concentrations required to inhibit non-inactivated Nav1.7. Compound 52 also reversed thermal hyperalgesia in the complete Freund’s adjuvant (CFA) model of pain. To study neuronal mechanisms, electrophysiological recordings were made in vivo from single nociceptive fibers from the rat tibial nerve one day after CFA injection. Compound 52 reduced the spontaneous firing of C-fiber nociceptors from approximately 0.7 Hz to 0.2 Hz and decreased the number of action potentials evoked by suprathreshold tactile and heat stimuli. It did not, however, appreciably alter the C-fiber thresholds for response to tactile or thermal stimuli. Surprisingly, compound 52 did not affect spontaneous activity or evoked responses of Aδ-fiber nociceptors. Results suggest that inhibition of inactivated states of TTX-S channels, mostly likely Nav1.7, in the peripheral nervous system produces analgesia by regulating the spontaneous discharge of C-fiber nociceptors.     

Trout thrombocytes contain 12- but not 5-lipoxygenase activity

Fish thrombocytes are thought to be the evolutionary forerunners of mammalian platelets. Thrombocyte preparations made by conventional methods, such as density gradient centrifugation, contain other cell types such as neutrophilic granulocytes and lymphocytes that could interfere with subsequent experiments. In this study, rainbow trout thrombocytes were separated by density gradient centrifugation and further purified by magnetic cell sorting (MACS) using the thrombocyte specific monoclonal antibody, 30D8. Thrombocyte purity was assessed by reactivity to 30D8 using flow cytometry and immunocytochemistry. Following purification by density gradient centrifugation, thrombocytes were 66.9±9.2% (mean value±S.E.M., n=3) pure. Further purification by MACS significantly increased thrombocyte purity to 97.3±0.6%, whereas only 1.4% of the MACS ?ve fraction were identified as these cells. Incubation of thrombocytes isolated by density gradient alone with calcium ionophore, A23187, generated a range of eicosanoids derived from arachidonic or eicosapentaenoic acids, namely, leukotriene (LT)B₄, LTB₅, lipoxin (LX)A₄, LXA₅, 12-hydroxyeicosatetraenoic acid (12-HETE) and 12-hydroxyeicosapentaenoic acid (12-HEPE). A similar eicosanoid generation profile was observed for cells in the MACS ?ve fraction; however, MACS +ve cells (thrombocytes) generated no 4 or 5 series LT or LX but did generate significant amounts of the 12-lipoxygenase (LO) products, 12-HETE and 12-HEPE. These results indicate that trout thrombocytes contain no demonstrable 5-LO activity and like their mammalian counterparts possess 12-LO activity.     

AMINO ACID SEQUENCE ANALYSIS OF THE SMALL SUBUNIT OF RIBULOSE BISPHOSPHATE CARBOXYLASE FROM FUCUS (PHAEOPHYCEAE)1

This paper reports for the first time amino acid sequence information for the small subunit of ribulose-1,5-bisphosphate carboxylase / oxygenase (Rubisco) from a non-green alga. N-terminal sequences are presented for the polypeptide from three species of the genus Fucus (Phaeophyceae). Although homologous to small subunit polypeptides from other organisms, the Fucus sequences exhibit a unique N-terminal section resembling neither cyanobacterial nor chlorophytic sequences. This difference may be a consequence of the plastid DNA coding arrangement for the small subunit in chromophytes, a situation reported for the related organism Olisthodiscus but not previously investigated at the amino acid sequence level.     

Enzymes of Fatty Acid β-Oxidation in Developing Brain

Developmental profiles were determined for the activities of eight enzymes involved in fatty acid beta-oxidation in rat brain. The enzymes studied were the palmitoyl-CoA, octanoyl-CoA, butyryl-CoA, glutaryl-CoA, and 3-hydroxyacyl-CoA dehydrogenases, the enoyl-CoA hydratase (crotonase), and the C4- and C10-thiolases. With the exception of the thiolases, all of the activities (expressed on the basis of brain weight) increased during the postnatal period of brain maturation. The activity of octanoyl-CoA dehydrogenase was elevated markedly compared to that of palmitoyl-CoA dehydrogenase at all developmental stages and in all brain regions in the rat. A similar relationship between these enzymes was observed in various regions of adult human brain. Comparisons of the activities of the beta-oxidation enzymes in human brain versus human skeletal muscle and in cultured neural cell lines (neuroblastoma and glioma) versus cultured skin fibroblasts revealed that the elevated activity of octanoyl-CoA dehydrogenase relative to palmitoyl-CoA dehydrogenase was specific to the neural tissues. This relationship was particularly evident when the enzyme activities were normalized to the activity of crotonase. The data support previous findings with radiochemical tracers, indicating that the brain is capable of utilizing fatty acids as substrates for oxidative energy metabolism. The relatively high activity of the medium-chain fatty acyl-CoA dehydrogenase in neural tissue may represent an adaptive mechanism to protect the brain from the known encephalopathic effects of octanoate and other medium-chain fatty acids that readily cross the blood-brain barrier.     

Excitotoxicity at Both NMDA and Non-NMDA Glutamate Receptors Is Antagonized by Aurintricarboxylic Acid: Evidence for Differing Mechanisms of Action

Abstract: In this study, the endonuclease inhibitor aurintricarboxylic acid (ATA) was examined for its ability to attenuate both acute and delayed excitotoxicity mediated through NMDA and non-NMDA glutamate receptors. Ex vivo embryonic chick retina, a model system frequently used for studies of excitotoxicity, was exposed to either 100 µM NMDA or kainate (KA) ± various concentrations of ATA for 60 min, then allowed to recover for 24 h. Lactate dehydrogenase release into the medium and histology were assessed as measures of delayed toxicity. ATA attenuated lactate dehydrogenase release due to NMDA or KA in a dose-dependent manner. Histology revealed that ATA decreased the number of pyknotic profiles in response to either glutamate agonist. The mechanism of ATA protection was addressed. ATA was found to block NMDA- but not KA-mediated ²²Na⁺ influx and cyclic GMP formation. In membrane binding studies, ATA was relatively selective for displacement at the NMDA receptor. The IC₅₀ values for displacement of [³H]CGS 19755, α-[³H]amino-3-hydroxy-5-methylisoxazole-4-propionic acid ([³H]AMPA), or [³H]KA were 29.9 ± 1.3, 313 ± 46, and >1,000 µM± SEM, respectively. ATA also fully attenuated NMDA-induced and partially attenuated KA-induced acute excitotoxicity as monitored histologically by tissue swelling and by the increase in GABA in the medium. Temporal studies of ATA efficacy indicated that ATA needed to be present during NMDA exposure to afford protection but, versus KA, was equally effective if administered immediately after KA exposure. Questions regarding the cellular penetration of ATA were raised because incubation with 100 µM ATA for 60 min had no effect on lactate formation or [³H]leucine incorporation into trichloroacetic acid-precipitable material, even though, in cell-free systems, ATA is a potent inhibitor of phosphofructokinase activity and protein synthesis. These studies demonstrate that ATA can protect against excitotoxicity mediated through NMDA or non-NMDA glutamate receptors. The mechanism of protection versus NMDA is through interruption of NMDA receptor interactions. ATA has no direct effect at the KA receptor; thus, its mechanism of protection versus KA is distinct from that versus NMDA and is, at present, unknown.     

IMMUNOLOCALIZATION OF CENTRIN DURING FERTILIZATION AND THE FIRST CELL CYCLE IN FUCUS DISTICHUS AND PELVETIA COMPRESSA (FUCALES,PHAEOPHYCEAE)1

Antibodies that recognize the centrosome-associated protein centrin were used to characterize centrosomal origin and positioning during fertilization and the first cell cycle in Fucus distichus subsp. evanescens (C. Agardh) Powell and Pelvetia compressa (J. Agardh) De Toni. Centrin was identified in sperm, eggs, and zygotes on protein blots, indicating the protein is present in both gametes. Using immunofluorescence microscopy, centrin was found in discrete foci in sperm. In contrast, eggs lack centrosomes and centrin was not detectable by immunofluorescence, indicating that centrin was probably dispersed in the cytoplasm. Two foci of centrin were present on the nuclear envelope of zygotes, but microtubules remained dispersed over the zygotic nucleus. Centrin foci separated over the nuclear envelope as the first cell cycle progressed. Microtubules became concentrated at the centrin foci to form centrosomes that gave rise to the spindle poles at mitosis.     

Male Territoriality in the Bumblebee Wolf,Philanthus bicinctus (Mickel) (Hymenoptera,Sphecidae): Observations on the Behaviour of Individual ♂♂

Observations were made on the behaviour of male Philanthus bicinctus (Mickel) which defend territories around the nesting burrows of ♀♀. ♂♂ were individually identified with small number tags and focal-animal samples were taken of the behaviour of these ♂♂. Intense interactions were observed between territorial ♂♂ and 1) conspecifics and 2) intruding insects which resembled conspecifics. Evidence is presented which suggests that ♂♂ scent mark their territories.     

Titles of related papers in other sections

A method is described for isolation of the Rhodopseudomonas viridis reaction center complex free of altered, 685 nm absorbing pigment. This improved preparation contains two c-type cytochromes in the ratio P-960: cytochrome c-558: cytochrome c-553 of 1 : 2 : 2 to 3. The near infrared spectral forms of the reduced preparation are located at 790, 832, 846 and 987 nm at 77 K; the oxidized complex absorbs at 790, 808, 829 and approx. 1310 nm. The 790 nm band is attributed to bacteriophaeophytin b and the other absorbances to bacteriochlorophyll b. The visible absorption bands may be assigned to these pigments and to the cytochromes present and, probably, to a carotenoid. The presence of two bacteriochlorophyll b spectral forms in the P⁺-830 band suggests that exciton interactions occur among pigments in the oxidized, as well as the reduced, reaction center. Changes in the 790 and 544 nm bands upon illumination of the reaction center preparation at low redox potential may be indicative of a role for bacteriophaeophytin b in primary photochemical events.     

Heterotopic bone formation: An apparently benign complication of median sternotomy

Two cases are reported that involve heterotopic bone formation in midline sternotomy scars. The authors relate similar complications associated with abdominal incisions and discuss possible causes.