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This review is about the development of three-dimensional (3D) ultrasonic medical imaging, how it works, and where its future lies. It assumes knowledge of two-dimensional (2D) ultrasound, which is covered elsewhere in this issue. The three main ways in which 3D ultrasound may be acquired are described: the mechanically swept 3D probe, the 2D transducer array that can acquire intrinsically 3D data, and the freehand 3D ultrasound. This provides an appreciation of the constraints implicit in each of these approaches together with their strengths and weaknesses. Then some of the techniques that are used for processing the 3D data and the way this can lead to information of clinical value are discussed. A table is provided to show the range of clinical applications reported in the literature. Finally, the discussion relating to the technology and its clinical applications to explain why 3D ultrasound has been relatively slow to be adopted in routine clinics is drawn together and the issues that will govern its development in the future explored.

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Understanding the regulatory mechanisms that are responsible for an organism's response to environmental change is an important issue in molecular biology. A first and important step towards this goal is to detect genes whose expression levels are affected by altered external conditions. A range of methods to test for differential gene expression, both in static as well as in time-course experiments, have been proposed. While these tests answer the question whether a gene is differentially expressed, they do not explicitly address the question when a gene is differentially expressed, although this information may provide insights into the course and causal structure of regulatory programs. In this article, we propose a two-sample test for identifying intervals of differential gene expression in microarray time series. Our approach is based on Gaussian process regression, can deal with arbitrary numbers of replicates, and is robust with respect to outliers. We apply our algorithm to study the response of Arabidopsis thaliana genes to an infection by a fungal pathogen using a microarray time series dataset covering 30,336 gene probes at 24 observed time points. In classification experiments, our test compares favorably with existing methods and provides additional insights into time-dependent differential expression.

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火炬松(Pinus taeda L.)原产美国东南部,是世界南方松中最重要的绿化和造林用速生针叶树种,现广泛分布于全球亚热带和部分热带地区,在我国的栽植面积居世界第2位,仅次于美国。目前,火炬松离体快速繁殖、遗传转化和品种改良研究中最大的障碍是没有获得良好的植株再生体系。本研究以火炬松的成熟种子为试材,建立了可调控的体细胞胚胎发生和器官发生植株再生系统,并对再生过程中的形态学变化进行了细胞学观察和扫描电镜观察;建立了胚性细胞悬浮系,测定了其重要生长参数的变化动态,优化了悬浮条件下体细胞胚胎发生的培养条件及悬浮细胞原生质体直接体细胞胚胎发生的培养条件。 进行了HA、HB、HC、MA、MB、MC、LA和LB等8种不同基因型的成熟合子胚在BMS、DCR、GD、LM、LP、MNCI、MS、SH及自行设计的TE等9种不同基本培养基上的愈伤组织诱导试验,筛选获得了愈伤组织发生频率较高的基因型HB、MA和MC,及基本培养基DCR和TE。激素组合试验表明,2,4-D和BA最有利于愈伤组织发生。两因子5水平等重复的愈伤组织诱导试验及方差分析结果证实,8 mg•L~(-1)2,4-D和4 mg•L~(-1)BA是愈伤组织诱导的最佳激素组合。诱导产生的愈伤组织经2次继代后,可明显分为4种类型,它们是1)白色、半透明、有光泽的粘性愈伤组织(WTGM);2)淡黄色、疏松、有光泽的颗粒状愈伤组织(YLGG);3)淡绿色、疏松的颗粒状愈伤组织(GLG);和4)浅白色、水浸状的粘性愈伤组织(WMM)。其中白色、半透明、有光泽的粘性愈伤组织有较强的体细胞胚胎发生能力,淡黄色、疏松、有光泽的颗粒状愈伤组织有较强的不定芽发生能力。这两种愈伤组织的最高诱导频率分别是28.1%和35.7%。 在附加2,4-D、IBA和BA的DCR体细胞胚诱导培养基上,白色、半透明、有光泽的粘性愈伤组织中的胚性细胞形成胚性胚柄细胞团和早期原胚。提高培养基中的渗透压后,早期原胚发育成后期原胚。在附加ABA、PEG和活性炭的DCR体细胞胚成熟培养基上,后期原胚发育成子叶胚。在无激素DCR培养基上,子叶胚萌发形成再生完整植株。体细胞胚转换成小植株的最高频率是18.4%。在直接体细胞胚诱导增养基和直接体细胞胚发育培养基的作用下,成熟合子胚的子叶和胚轴上直接形成体细胞胚。直接体细胞胚胎发生的最高频率是18%。 在附加NAA、IBA和BA的TE不定芽原基诱导培养基上,淡黄色、疏松、有光泽的颗粒状愈伤组织中的胚性细胞形成不定芽原基。在附加IBA和BA的TE不定芽分化培养基上,不定芽原基分化产生不定芽。用基因型HB、MA和MC的淡黄色、疏松、有光泽的颗粒状愈伤组织进行的试验表明,不定芽分化的最佳低温(4 ℃)处理时间是5~6周,最佳蔗糖浓度是25~30 g•L~(-1)。分化产生的不定芽在附加IBA、GA_3和活性炭的TE培养基上,幼茎伸长。附加IBA、BA和GA_3的TE培养基上,伸长的不定芽生根形成完整植株。伸长不定芽的最高生根频率是46%。成熟合子胚在直接不定芽原基诱导培养基及直接不定芽分化培养基的作用下,从子叶和胚轴的不同部位产生直接不定芽。直接不定芽发生的最高频率是58.2%。 由成熟合子胚诱导愈伤组织形成过程中的形态学观察表明:在附加2,4-D和BA的DCR愈伤组织诱导培养基上,HB、MA和MC3种基因型中,MA主要在下胚轴形成愈伤组织,MC主要在子叶和胚根形成愈伤组织,HB主要在胚根形成体积较小的愈伤组织。在附加NAA和BA的TE愈伤组织诱导培养基上,HB、MA和MC3种基因型中,MA在单个子叶的顶端形成生长较快的愈伤组织,MC的所有子叶都形成愈伤组织,HB在所有子叶的顶端形成愈伤组织。 石蜡切片观察表明:4类愈伤组织的细胞组成不同.第1类愈伤组织主要由核大、质浓、体积小的园形胚性细胞及核呈柱状或新月形的体积较大的非胚性细胞组成;第2类愈伤组织主要由核大、质浓、体积小的园形胚性细胞组成,第3类愈伤组织主要由体积较大的棒状、葫芦形、新月形、盾片状细胞组成、第4类愈伤组织主要由体积较大的薄壁细胞和细胞壁加厚、细胞间连结紧密、无细胞核的分化细胞组成,第1类愈伤组织上形成的早期原胚的特点是:胚性头部由排列紧密、体积小的园形细胞组成,轮廓十分清晰、呈半圆形,胚柄由排列疏松的长形细胞组成,细胞体积大、细胞中有大的液泡,早期原胚在发育过程中和母体组织保持一定的隔离状态。第2类愈伤组织上形成的不定芽的特点是t结构上为单极性,其维管束和母体组织保持密切联系。扫描电镜观察表明;直接体细胞胚基部和母体组织保持较少的联系,其子叶是直立生长的.直接不定芽基部和母体组织保持较多的联系,其幼叶是向心卷曲生长的。 在培养周期内,基因型HB、MA和MC胚性细胞悬浮培养物的几个生长参数的变化动态相似。鲜重增长高峰在12—15 d,干重增长高峰在15~18 d,细胞体积增长高峰和胚数增长高峰在18—21 d。在培养的18—21 d,培养液中的pH值、电导率和蔗糖浓度接近或降到最低点。在悬浮培养条件下,体细胞胚形成的最佳起始细胞密度是5~6×103个/ml。继代培养时间延长,体细胞胚胎发生能力下降。热激处理促进基因型HB和MA体细胞胚的形成,抑制基因型MC体细胞胚的形成。在悬浮培养物中,观察到了裂生多胚。 对数生长期的火炬松胚性悬浮细胞,在以甘露醇作为渗透压稳定剂的酶混合液Cel-lulase“Onozuka”RS l%+Cellulase“Onozuka”R-10 2.5%+Pectolyase Y-23 0.2%的作用下,原生质体的产量和活力均最高。原生质体在DCR和KM8P两种培养基上形成了体细胞胚(包括胚性胚柄细胞团、早期原胚和后期原胚).体细胞胚形成的最佳起始原生质体密度是7×l04个/ml,最佳ABA浓度是4 mg.L-I.

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Benthic food webs often derive a significant fraction of their nutrient inputs from phytoplankton in the overlying waters. If the phytoplankton include harmful algal species like Pseudo-nitzschia australis, a diatom capable of producing the neurotoxin domoic acid (DA), the benthic food web can become a depository for phycotoxins. We tested the general hypothesis that DA contaminates benthic organisms during local blooms of P. australis, a widespread toxin producer along the US west coast. To test for trophic transfer and uptake of DA into the benthic food web, we sampled 8 benthic species comprising 4 feeding groups: filter feeders (Emerita analoga and Urechis caupo); a predator (Citharichthys sordidus); scavengers (Nassarius fossatus and Pagurus samuelis) and deposit feeders (Neotrypaea californiensis, Dendraster excentricus and Olivella biplicata). Sampling occurred before, during and after blooms of P. australis in Monterey Bay, CA, USA during 2000 and 2001. DA was detected in all 8 species, with contamination persisting over variable time scales. Maximum DA levels in N. fossatus (674 ppm), E. analoga (278 ppm), C. sordidus (515 ppm), N. californiensis (145 ppm), P. samuelis (56 ppm), D. excentricus (15 ppm) and O. biplicata (3 ppm) coincided with P. australis blooms, while DA levels in U. caupo remained above 200 ppm (max. = 751 ppm) throughout the study period. DA in 6 species exceeded levels thought to be safe for higher level consumers (i.e. ≥20 ppm) and thus is likely to have deleterious effects on marine birds, sea lions and the endangered California sea otter, known to prey upon these benthic species.

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The blue crab (Callinectes sapidus) plays an important economic and ecological role in estuaries and coastal habitats from the Gulf of Mexico to the east coast of North America, but demographic assessments are limited by length-based methods. We applied an alternative aging method using biochemical measures of metabolic byproducts (lipofuscins) sequestered in the neural tissue of eyestalks to examine population age structure. From Chesapeake Bay, subsamples of animals collected from the 1998–99 (n=769) and 1999–2000 (n=367) winter dredge surveys were collected and lipofuscin was measured. Modal analysis of the lipofuscin index provided separation into three modes, whereas carapace-width data collected among the same individuals showed two broad modes. Lipofuscin modal analysis indicated that most adults (carapace width >120 mm) were <2 years old. The results indicate that use of extractable lipofuscin can provide a more accurate and better resolved estimation of demographic structure of blue crab populations in the field than size alone.