Deep soil heterogeneity and fine root distribution in forests and pastures of eastern Amazonia

Little is known about deep soil heterogeneity, or its relationship with fine root distribution. Beneath a mature, closed-canopy forest of eastern Amazonia, and the pastures and secondary forests that are derived from this forest, soil soft spots and hollow chambers occur to at least 9 meters depth. We measured the vertical distribution of these soil patches, and compared chemical characteristics, mycorrhizal infection, and root density of soil soft spots with the surrounding matrix of more homogeneous soil. Soil soft spots and chambers varied little with depth, but occupied the greatest soil volume (0.8 to 1.2%) from 4 to 6 m depth in the mature forest. Soft spots had lower pH, P availability and arbuscular mycorrhizal infection, and higher K availability than surrounding soil. Root length density was 2 to 15 times higher in soft spots than in surrounding soil. In the pastures, roots were found only in soil soft spots at depths of >3 m. Pastures and secondary forest had more soil chambers in the upper meter of soil than mature forest, but were otherwise indistinguishable in their patterns of deep soil heterogeneity. Soil soft spots may be vestiges of cutter ant nest chambers, while hollow chambers are cutter ant chambers and root channels. Chambers may act as conduits for root penetration and water penetration to deep soil.Abbreviations AM arbuscular mycorrhizae - RLD root length density (root length per unit of soil volume)     

基于F3Net显著性目标检测的蝴蝶图像前背景自动分割

[目的]具有复杂背景的蝴蝶图像前背景分割难度大.本研究旨在探索基于深度学习显著性目标检测的蝴蝶图像自动分割方法.[方法]应用DUTS-TR数据集训练F3Net显著性目标检测算法构建前背景预测模型,然后将模型用于具有复杂背景的蝴蝶图像数据集实现蝴蝶前背景自动分割.在此基础上,采用迁移学习方法,保持ResNet骨架不变,利...     

Circulatory function at sub-zero temperature: venous responses to catecholamines and angiotensin II in the Antarctic fish <Emphasis Type="Italic">Pagothenia borchgrevinki</Emphasis>

Catecholamines increase arterial pressure by increasing cardiac output (Q) and stroke volume (V _s), while angiotensin II (ang II) also increases vascular resistance (R _sys) in the Antarctic fish Pagothenia borchgrevinki. Adrenaline, phenylephrine and ang II (Asn¹, Val⁵) were injected into P. borchgrevinki. Cardiovascular variables, including central venous pressure (P _cv) and mean circulatory filling pressure (P _mcf; an index of venous capacitance), were recorded to investigate if venous vasoconstriction can explain the increased V _s and Q and the arterial pressor response in this species. Routine P _cv and P _mcf were 0.11 ± 0.01 and 0.18 ± 0.02 kPa, respectively. All of the drugs caused moderate increases in P _cv and P _mcf and the responses were attenuated after α-adrenergic blockade with prazosin. Although dorsal aortic pressure (P _da) also increased in response to all agonists, the mechanisms differed. Adrenaline caused sustained increases in V _s and Q, while R _sys only rose transiently. Ang II had a slower effect than adrenaline and increased both R _sys and Q, while phenylephrine only increased R _sys. This study demonstrates that P _cv is positive and controlled by an α-adrenergic mechanism in P. borchgrevinki. However, given the relatively small venous response to adrenaline it seems more likely that the increases in V _s and Q from this agonist are due to direct effects on the heart.     

Biogeography of Rhizobium radiobacter and distribution of associated temperate phages in deep subseafloor sediments

Bacteriophages might be the main ‘predators'' in the marine deep subsurface and probably have a major impact on indigenous microbial communities. To identify their function within this habitat, we have determined their abundance and distribution along the sediment columns of two continental margin and two open ocean sites that were recovered during Leg 201 of the Ocean Drilling Program. For all investigated sites, viral abundance followed the total cell numbers with a virus-to-cell ratio between 1 and 10 in the upper 100 mbsf (meters below seafloor). An increasing ratio of about 20 in deeper layers indicated an ongoing viral production in up to 11 Ma old sediments. We have used Rhizobium radiobacter as the most frequently isolated organism from the deep subsurface with a high in situ abundance to identify the frequency of associated rhizobiophages. In this study, 16S rRNA gene copies of R. radiobacter accounted for up to 5.6% of total bacterial 16S rRNA genes (average: 0.75%) as detected by quantitative PCR. A distinctive distribution was identified for R. radiobacter as indicated by a site-specific arrangement of genetically similar populations. Whole genome information of rhizobiophage RR1-A was used to generate a primer system for quantitative PCR specifically targeting the prophage antirepressor gene, indicative for temperate phages. The quantification of this gene within various sediment horizons showed a contribution of temperate phages of up to 14.3% to the total viral abundance. Thus, the high amount of temperate phages within the sediments and among all investigated isolates indicates that lysogeny is the main viral proliferation mode in deep subsurface populations.     

重组水蛭素的抗血栓形成作用及其机制

目的：研究重组水蛭素抗血栓形成的作用及机制。方法：将60只雄性昆明小鼠随机分为对照组、模型组、阿司匹林组和重组水蛭素低、中、高剂量组（n=10）。除对照组外,其余各组小鼠分别腹腔注射角叉菜胶2.5 mg/kg,诱发小鼠尾部血栓形成。注射角叉菜胶前24 h、0.5 h和注射后24 h,阿司匹林组小鼠分别腹腔注射阿司匹林25 mg/kg,重组水蛭素低、中、高剂量组小鼠分别腹腔注射0.05、0.1、0.2 mg/kg重组水蛭素,对照组和模型组小鼠分别腹腔注射等体积生理盐水。注射角叉菜胶后48 h,观察小鼠黑尾长度并计算黑尾发生率;检测血浆凝血酶原时间（PT）、活化部分凝血活酶时间（APTT）、组织型纤溶酶原激活剂（t-PA）、纤溶酶原激活物抑制因子-1（PAI-1）、6-酮-前列腺素F1α（6-keto-PGF1α）、血栓恶烷B2（TXB2）水平。结果：与对照组比较,模型组小鼠尾部形成血栓;血浆PT明显缩短（P<0.01）,PAI-1、TXB2水平明显升高（P<0.01）,t-PA、6-keto-PGF1α水平明显降低（P<0.01）。与模型组比较,重组水蛭素低、中、高剂量组和阿司匹林组小鼠尾部血栓长度明显缩短（P<0.05或P<0.01）,PT明显延长（P<0.01）,PAI-1、TXB2水平明显降低（P<0.01）,t-PA、6-keto-PGF1α水平明显升高（P<0.01）。与阿司匹林组比较,重组水蛭素低剂量组小鼠尾部血栓长度明显增加（P<0.05）,PT明显缩短（P<0.01）,PAI-1、TXB2水平明显升高（P<0.01）;重组水蛭素低、中剂量组6-keto-PGF1α水平明显降低（P<0.01,P<0.05）;重组水蛭素中剂量组PAI-1、TXB2水平明显升高（P<0.01,P<0.05）。结论：重组水蛭素有明显抗血栓形成作用,其机制可能与影响外源性凝血系统、促进纤溶功能有关。     

Deep homology: A view from systematics

Over the past decade, it has been discovered that disparate aspects of morphology – often of distantly related groups of organisms – are regulated by the same genetic regulatory mechanisms. Those discoveries provide a new perspective on morphological evolutionary change. A conceptual framework for exploring these research findings is termed ‘deep homology’. A comparative framework for morphological relations of homology is provided that distinguishes analogy, homoplasy, plesiomorphy and synapomorphy. Four examples – three from plants and one from animals – demonstrate that homologous developmental mechanisms can regulate a range of morphological relations including analogy, homoplasy and examples of uncertain homology. Deep homology is part of a much wider range of phenomena in which biological (genes, regulatory mechanisms, morphological traits) and phylogenetic levels of homology can both be disassociated. Therefore, to understand homology, precise, comparative, independent statements of both biological and phylogenetic levels of homology are necessary.     

Regulatory RNAs derived from transfer RNA?

Four recent studies suggest that cleavages of transfer RNAs generate products with microRNA-like features, with some evidence of function. If their regulatory functions were to be confirmed, these newly revealed RNAs would add to the expanding repertoire of small noncoding RNAs and would also provide new perspectives on the coevolution of transfer RNA and messenger RNA.     

Ethical concerns regarding commercialization of deep brain stimulation for obsessive compulsive disorder

The United States Food and Drug Administration's recent approval of the commercial use of Deep Brain Stimulation (DBS) as a treatment for Obsessive Compulsive Disorder (OCD) will be discussed within the context of the existing USA regulatory framework. The purpose will be to illustrate the current lack of regulation and oversight of the DBS market, which has resulted in the violation of basic ethical norms. The discussion will focus on: 1) the lack of available evidence on procedural safety and efficacy, 2) the numerous conflicts of interest held by research investigators, and 3) the ambiguity of both aforementioned categories due to an inherent lack of transparency in the research. It is argued that in order to address these issues, ethical analyses of DBS for psychiatric disorders must include the role of the industry forces that have become the primary impetus for this research. As such, DBS for OCD serves as an important case example in studies of neurotechnology and innovative surgery.     

Rare and new cumaceans (Crustacea,Peracarida) from?the southern margin of the Cap Ferret Canyon (Bay of Biscay)

A new cumacean genus and species, Ithyleucon sorbeigen. et sp. n., was described from material collected in the southern margin of the Cap Ferret Canyon (Bay of Biscay, NE Atlantic). Although the new genus resembles Pseudoleucon Zimmer, 1903, in terms of the general aspect of the carapace and the pseudo-rostrum position, it shows important differences in the uropod structure and in the size of the antenna 1 accessory flagellum. In addition, some comments regarding the morphology of certain rare species (Mesolamprops denticulatus Ledoyer, 1983, Hemilamprops normani Bonnier, 1896 and Schizocuma spino-culatum (Jones, 1984)) are also provided.