Organization of the cerebellar cortex viewed by scanning electron microscopy

An improved method of preparing central nervous system tissue for examination in a scanning electron microscope is described. In cerebellar cortex, the precise distribution of synaptic junctions on Purkinje cell bodies, as well as complex arrangements of neurites in the glomeruli of the granule cell layer, are directly visualized. The method also provides views of glial cell processes investing brain surfaces, blood vessels and neurons. The principal advantage of a scanning electron microscopic study is that relationships between cells in the brain can be seen directly instead of inferred from laborious serial reconstructions or other more complex and indirect anatomical methods.     

Prolonged inhibition of primate spinothalamic tract cells by peripheral nerve stimulation

Inhibition of spinothalamic tract (STT) cells was produced by repetitive peripheral nerve conditioning stimulation with high intensity and low frequency pulses. Identified STT cells were recorded from the lumbosacral spinal cord of intact, anesthetized monkeys. In addition, presumed STT cells were recorded from both unanesthetized, decerebrated and decerebrated, spinalized monkeys. These cells were identified by antidromically activating them from the contralateral ventral lateral funiculus of the cervical spinal cord. Both C fiber activity evoked by electrical stimulation of the sural nerve and activity evoked by noxious heat were greatly inhibited by repetitive conditioning stimuli applied either to the common peroneal or tibial nerve with a strong enough intensity for activation of C fibers at 2 Hz for 15 min. The inhibition was maintained during the period of conditioning stimulation and often outlasted stimulation by 20-30 min. The inhibition of cells produced by peripheral nerve stimulation was observed in decerebrate and spinalized animals as well as in intact anesthetized monkeys, although the mean recovery time in the decerebrate group was faster. This indicates that anesthetics did not interfere with the inhibitory mechanism. Furthermore, the presence of inhibition in spinalized animals means the inhibition must depend in part on spinal cord neuronal circuitry. Intravenous injection of naloxone produced a significant but small reduction of the recovery phase of the inhibition. No pharmacological agent was found that substantially interfered with the powerful inhibition produced during peripheral conditioning stimuli. The experimental animal model used in these experiments seems appropriate for studying the mechanisms of analgesia produced by peripheral nerve stimulation.     

The chemical-in-μwell: a high-throughput technique for identifying solutes eliciting a chemotactic response in motile bacteria

Bacteria, and in particular marine bacteria, can be found in environments that are poor in nutrients. To survive, they are able to move toward more favorable niches by a mechanism called chemotaxis, whose first step consists in the detection of substrates by chemoreceptors. We developed a chemotactic assay enabling rapid testing of several hundred different solutes and we identified several molecules eliciting a chemotactic response from two aquatic Shewanella species. We propose that this assay be used for other bacteria to determine the repertoire of chemotactic molecules, generally not clearly elucidated.     

Cadmium sensitivity, uptake, subcellular distribution and thiol induction in a marine diatom: exposure to cadmium

The aims of this study were to (1) evaluate the changes in the Cd tolerance of a marine diatom after exposure under different Cd concentrations for various durations and (2) to explore the potential subcellular and biochemical mechanisms underlying these changes. The 72-h toxicity, short-term Cd uptake, subcellular Cd distribution, as well as the synthesis of phytochelatins (PCs) were measured in a marine diatom Thalassiosira nordenskioeldii after exposure to a range of free Cd ion concentrations ([Cd²⁺], 0.01-84 nM) for 1-15 days. Surprisingly, the diatoms did not acquire higher resistance to Cd after exposure; instead their sensitivity to Cd increased with a higher exposed [Cd²⁺] and a longer exposure period. The underlying mechanisms could be traced to the responses of Cd cellular accumulation and the intrinsic detoxification ability of the preconditioned diatoms. Generally, exposure to a higher [Cd²⁺] and for a longer period increased the Cd uptake rate, cellular accumulation, as well as the Cd concentration in metal-sensitive fraction (MSF) in these diatoms. In contrast, although PCs were induced by the environmental Cd stress (with PC₂ being the most affected), the increased intracellular Cd to PC-SH ratio implied that the PCs’ detoxification ability had reduced after Cd exposure. All these responses resulted in an elevated Cd sensitivity as exposed [Cd²⁺] and duration increased. This study shows that the physiological/biochemical and kinetic responses of phytoplankton upon metal exposure deserve further investigation.     

Growth Inhibition and Apoptosis with H31 Metabolites from Marine Bacillus SW31 in Head and Neck Cancer Cells

Objectives

To determine whether a novel marine micro-organism with anticancer properties, H31, the metabolic product of Bacillus SW31, has anti-tumor effects on head and neck cancer, and potential for apoptotic-enhancing anti-cancer treatment of affected patients.

Methods

The cell viability and apoptosis assays were performed. Changes in the signal pathway related to apoptosis were investigated. Then, the therapeutic effects of H31 were explored in mouse xenograft model and drug toxicity of H31 was examined in zebrafish model.

Results

We identified the anticancer activity of H31, a novel metabolic product of Bacillus SW31. Bacillus SW31, a new marine micro-organism, has 70% homology with Bacillus firmus and contains potent cytotoxic bioactivity in head and neck cancer cells using MTT assay. Combined with c-JUN, p53, cytochrome C, and caspase-3, H31 induced apoptosis of KB cells, a head and neck cancer cell line. In a separate in vivo model, tumor growth in C3H/HeJ syngeneic mice was suppressed by H31. In addition, in a zebrafish model used for toxicity testing, a considerable dose of H31 did not result in embryo or neurotoxicity.

Conclusion

Growth inhibition and apoptosis were achieved both in vitro and in vivo in head and neck cancer cells after exposure to H31, a metabolite from the marine Bacillus species, without any significant toxicity effects even at considerable H31 dose concentrations.     

Organochlorine pesticides in commercial marine fishes of Coimbatore, India and their suitability for human consumption

Organochlorine pesticide residues were determined in 10 species of fishes caught at Cochin and Rameshwaram coast, and sold in Coimbatore, Tamil Nadu, India. Species were selected on the basis of their regular availability throughout the year and commercial value. A total of 389 fishes were analyzed for organochlorine residues and their suitability for human consumption was evaluated. Results show varying levels of residues of hexachlorocyclohexane (HCH), DDT, heptachlor epoxide, endosulfan and dieldrin. Among the 10 species, high concentration of pesticide residues were recorded in Sardinella longiceps, Carangoides malabaricus, Chlorophthalmus agassizi, Saurida tumbil and Rastrelliger kanagurta. The variation in total organochlorine residues among species and between places was not significant (P>0.05). Only five species of fishes showed monthly variation in residue levels and there was no significant correlation between the body size and residue levels in the tissue. About 22% of the fishes exceeded the maximum residue limits (MRL) of total HCH prescribed by FAO/WHO for fish products. The calculated dietary intake of total HCH through consumption of C. malabaricus, C. agassizi and S. longiceps exceeded the maximum acceptable dietary intake (ADI) limits prescribed for human consumption. The present study recommends continuous monitoring of environmental contaminants in marine fishes to assess the possible impact on human health.     

海洋放线菌M324抗菌物质的发酵优化与性质的初步研究

M324是从中国连云港沿海海泥中分离到的一株能产生较广谱抗菌活性物质的海洋放线菌。文章报道了对该菌株的初步鉴定、发酵条件的优化和产生抗菌活性物质的部分性质的探索性研究结果结果。发现M324为一株具有耐盐作用的链霉菌属白孢类群白孢亚群类似白长链霉菌的海洋放线菌。在28℃、pH为7．0、培养5d，其产生的抗菌活性物质的活性最强。发酵产物对酸碱稳定，呈现强极性，并呈现广谱抗菌活性。海洋放线菌M324能产生极性大的广谱抗菌活性物质，有较好的研究前景。     

研究开发中的海洋抗癌活性物质

海洋天然产物现已成为临床抗癌药物的重要来源，从didenmline B开始，进入临床研究的抗癌活性物质已经有二十多种。根据海洋来源抗癌活性物质的作用靶点不同，系统综述了正在研究中的十几种来源于海洋的天然抗癌活性物质的作用机制和研究开发情况等。     

海洋中药发展源流初探

根据考古发现,人类早在旧石器时代即已开始利用海洋资源.到了春秋战国时期,人类开始利用海洋生物入药,并对其功效、炮制有简单的认识.到了秦汉时期,人类对海洋中药的认识进一步深化,并创制了运用海洋药物的方剂.到了唐宋时期,海洋中药的种数以及相应的方剂明显增多,对海洋中药的性味功效以及配伍规律有了进一步认识,其治疗范围也明显扩大.明清时期,人类对海洋中药的认识主要是对前人经验的总结.建国后,由于科学技术的发展,人类开发、利用海洋资源的能力大幅提高,海洋中药的种数达到1 000余种.但海洋中药的发展也面临着新的问题,即海洋中药的种数虽然增加,但对其性味功效的认识则明显滞后,严重影响了海洋中药的临床应用.     

Occurrence of saxitoxins as a major toxin in the ovary of a marine puffer Arothron firmamentum.

Eleven male and 14 female specimens of a marine puffer Arothron firmamentum were collected from Oita and Iwate Prefectures, Japan. The toxicity assay using mouse showed that only ovary and skin of the female specimens were toxic, the toxicity scores being 5-740 as paralytic shellfish poison and <5-30 MU/g as tetrodotoxin (TTX), respectively. The toxin extracts from the both tissues were then treated with cartridge columns, and subjected to high performance liquid chromatography and liquid chromatography-mass spectral analyses. In the analyses, saxitoxin (STX) and decarbamoylSTX (dcSTX) were identified as the major toxins in the ovary, while the skin contained only TTX.