Resonance Raman studies of cytochrome P450BM3 and its complexes with exogenous ligands.

Resonance Raman spectra are reported for both the heme domain and holoenzyme of cytochrome P450BM3 in the resting state and for the ferric NO, ferrous CO, and ferrous NO adducts in the absence and presence of the substrate, palmitate. Comparison of the spectrum of the palmitate-bound form of the heme domain with that of the holoenzyme indicates that the presence of the flavin reductase domain alters the structure of the heme domain in such a way that water accessibility to the distal pocket is greater for the holoenzyme, a result that is consistent with analogous studies of cytochrome P450cam. The data for the exogenous ligand adducts are compared to those previously reported for corresponding derivatives of cytochrome P450cam and document significant and important differences for the two proteins. Specifically, while the binding of substrate induces relatively dramatic changes in the nu(Fe-XY) modes of the ferrous CO, ferric NO, and ferrous NO derivatives of cytochrome P450cam, no significant changes are observed for the corresponding derivatives of cytochrome P450BM3 upon binding of palmitate. In fact, the spectral data for substrate-free cytochrome P450BM3 provide evidence for distortion of the Fe-XY fragment, even in the absence of substrate. This apparent distortion, which is nonexistent in the case of substrate-free cytochrome P450cam, is most reasonably attributed to interaction of the Fe-XY fragment with the F87 phenylalanine side chain. This residue is known to lie very close to the heme iron in the substrate-free derivative of cytochrome P450BM3 and has been suggested to prevent hydroxylation of the terminal, omega, position of long-chain fatty acids.     

Phase II protocol for the evaluation of new treatments in patients with advanced gastric carcinoma: results of ECOG 5282

The study was a Phase II randomized study to evaluate the efficacy of new agents for the treatment of advanced gastric carcinoma. Patients were randomized to receive single agent chemotherapy with mitoxantrone, etoposide, aclacinomycin-A or spirogermanium. The patients were stratified by prior use of chemotherapy, prior doxorubicin use and ECOG performance status. Patients with a history of cardiac disease or prior doxorubicin exceeding a dose of 400 mg/m² were restrictively randomized to sopirogermanium or etoposide only. One hundred and fourteen patients were registered for the study. Among 98 evaluable patients there were only two partial responses (both in the etoposide arm), and one complete response in the mitoxantrone arm. The median survival on the study was 3.3 months. One hundred and six patients were analyzable for toxicity. There were four treatment-related deaths and four life-threatening toxicities. Because of low response rates and relatively high toxicities the studied compounds were not deemed worth further investigation for advanced gastric cancer.     

Spatial Behavior Comparison of Bactericera cockerelli Sulc. (Hemiptera: Triozidae) in Mexico

During the last five?years, Bactericera cockerelli Sulc. has caused significant economic losses in potato production in Mexico, due to the purple top and zebra chip diseases, since it acts as the vector of Candidatus Liberibacter psyllaurous. Despite its importance as a vector of serious potato diseases, the knowledge of its spatial distribution behavior, which could improve the efficiency of control measures, is entirely lacking. The main objective of this work was to compare the spatial distribution of the immature and adult stages of B. cockerelli obtained in a potato field by means of transect and quadrant sampling techniques and of geostatistics tools that allow the visualization of its spatial distribution in the field. Transect and quadrant samplings showed that the immature stages (eggs and nymphs) of B. cockerelli present a clustered distribution. The validation of the achieved semivariograms in the three dates of sampling corroborated the aggregated distribution of immatures and adults of the insect. The maps obtained in the sampling by using the quadrant or the transect approaches reflect the aggregated structure of the insect populations which did not infest 100% of the plot area. This allowed us to identify infested and free areas, what will aid in decisions for selecting alternatives of control.     

黑龙江和图们江流域菱属(Trapa L.)植物分布格局及形态多样性

菱属(Trapa L.)的系统分类一直存在较大分歧,至今还没有一个比较公认的分类系统。黑龙江和图们江流域是菱属物种多样性的重要分布区之一,为了揭示该流域菱属植物的地理分布格局和形态多样性,我们进行了大量实地调查和研究。结果显示,从该地区28个湖中共采集到菱属11个种及8个种内变异类型,表明它们具有丰富的形态多样性;结合查阅菱属354份标本资料,共获得92个分布地点数据;采集到的11个物种的地理分布格局呈不均衡性,其中细果野菱(Trapa maximowiczii Korsch.)分布最广,野菱(Trapa incisa Siebold et Zucc.)、兴凯菱(Trapa khankensis Pshennikova)和科热夫尼科夫菱(Trapa kozhevnikovirum Pshennikova)为狭域分布种;东部乌苏里江和图们江流域是菱属物种多样性的分布中心,可能是第四纪冰期避难所;菱属植物多数种间形态特性相对稳定,东北菱(Trapa manshurica Fler.)、耳菱(Trapa potaninii V.Vassil)、丘角菱(Trapa japonica Fler.)、西伯利亚菱(Trapa sibirica Fler.)和细果野菱共有8个种内形态变异类型;种群内多数分类性状稳定,种群间形态变异较明显;菱属植物分布格局不均衡和种内形态变异的形成可能与基因流的扩散限制有关。本研究结果为进一步澄清菱属分类混乱问题奠定了基础,进一步结合分子标记技术研究系统演化关系将对揭示菱属的进化历史具有重要意义。     

Host habitat assessment by a parasitoid using fungal volatiles

Background

The genus Mantella, endemic poison frogs of Madagascar with 16 described species, are known in the field of international pet trade and entered under the CITES control for the last four years. The phylogeny and phylogeography of this genus have been recently subject of study for conservation purposes. Here we report on the studies of the phylogeography of the Mantella cowani group using a fragment of 453 bp of the mitochondrial cytochrome b gene from 195 individuals from 21 localities. This group is represented by five forms: M. cowani, a critically endangered species, a vulnerable species, M. haraldmeieri, and the non-threatened M. baroni, M. aff. baroni, and M. nigricans.

Results

The Bayesian phylogenetic and haplotype network analyses revealed the presence of three separated haplotype clades: (1) M. baroni, M. aff. baroni, M. nigricans, and putative hybrids of M. cowani and M. baroni, (2) M. cowani and putative hybrids of M. cowani and M. baroni, and (3) M. haraldmeieri. The putative hybrids were collected from sites where M. cowani and M. baroni live in sympatry.

Conclusion

These results suggest (a) a probable hybridization between M. cowani and M. baroni, (b) a lack of genetic differentiation between M. baroni/M. aff. baroni and M. nigricans, (c) evidence of recent gene-flow between the northern (M. nigricans), eastern (M. baroni), and south-eastern (M. aff. baroni) forms of distinct coloration, and (d) the existence of at least three units for conservation in the Mantella cowani group.     

Nociceptin and its natural and specifically‐modified fragments: Structural studies

The vibrational structures of Nociceptin (FQ), its short bioactive fragments, and specifically‐modified [Tyr¹]FQ (1‐6), [His¹]FQ (1‐6), and [His^1,4]FQ (1‐6) fragments were characterized. We showed that in the solid state, all of the aforementioned peptides except FQ adopt mainly turn and disordered secondary structures with a small contribution from an antiparallel β‐sheet conformation. FQ (1‐11), FQ (7‐17) [His¹]FQ (1‐6), and [His^1,4]FQ (1‐6) have an α‐helical backbone arrangement that could also slightly influence their secondary structure. The adsorption behavior of these peptides on a colloidal silver surface in an aqueous solution (pH = ～8.3) was investigated by means of surface‐enhanced Raman scattering (SERS). All of the peptides, excluding FQ (7‐17), chemisorbed on the colloidal silver surfaces through a Phe⁴ residue, which for FQ, FQ (1‐11), FQ (1‐6), [Tyr¹]FQ (1‐6), and [His¹]FQ (1‐6) lies almost flat on this surface, while for FQ (1‐13) and FQ (1‐13)NH₂ adopts a slightly tilted orientation with respect to the surface. The Tyr¹ residue in [Tyr¹]FQ (1‐6) does not interact with the colloidal silver surface, suggesting that the Tyr¹ and Phe⁴ side chains are located on the opposite sides of the peptide backbone, which can be also true for His¹ and Phe⁴ in [His¹]FQ (1‐6). The lone pair of electrons on the oxygen atom of the ionized carbonyl group of FQ (1‐13) and FQ (7‐17) appears to be coordinated to the colloidal silver nanoparticles, whereas in the case of the remaining peptides, it only assists in the adsorption process, similar to the ? NH₂ group. We also showed that upon adsorption, the secondary structure of these peptides is altered. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 1039–1054, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com