Structure learning in action.

'Learning to learn' phenomena have been widely investigated in cognition, perception and more recently also in action. During concept learning tasks, for example, it has been suggested that characteristic features are abstracted from a set of examples with the consequence that learning of similar tasks is facilitated-a process termed 'learning to learn'. From a computational point of view such an extraction of invariants can be regarded as learning of an underlying structure. Here we review the evidence for structure learning as a 'learning to learn' mechanism, especially in sensorimotor control where the motor system has to adapt to variable environments. We review studies demonstrating that common features of variable environments are extracted during sensorimotor learning and exploited for efficient adaptation in novel tasks. We conclude that structure learning plays a fundamental role in skill learning and may underlie the unsurpassed flexibility and adaptability of the motor system.

Characterization of the U.S. Gulf of Mexico and South Atlantic penaeid and rock shrimp fisheries based on observer data

In July 2007, a mandatory Federal observer program was implemented to characterize the U.S. Gulf of Mexico penaeid shrimp (Farfantepenaeus aztecus, F. duorarum, and Litopenaeus setiferus) fishery. In June 2008, the program expanded to include the South Atlantic penaeid and rock shrimp, Sicyonia spp., fisheries. Data collected from 10,206 tows during 5,197 sea days of observations were analyzed by geographical area and target species. The majority of tows (~70%) sampled were off the coasts of Texas and Louisiana. Based on total hours towed, the highest concentrated effort occurred off South Texas and southwestern Florida. Gear information, such as net characteristics, bycatch reduction devices, and turtle excluder devices were fairly consistent among areas and target species. By species categories, finfish comprised the majority (≥57%) of the catch composition in the Gulf of Mexico and South Atlantic penaeid shrimp fisheries, while in the South Atlantic rock shrimp fishery the largest component (41%) was rock shrimp. Bycatch to shrimp ratios were lower than reported in previous studies for the Gulf of Mexico penaeid shrimp fishery. These decreased ratios may be attributed to several factors, notably decreased shrimp effort and higher shrimp catch per unit of effort (CPUE) in recent years. CPUE density surface plots for several species of interest illustrated spatial differences in distribution. Hot Spot Analyses for shrimp (penaeid and rock) and bycatch species identified areas with significant clustering of high or low CPUE values. Spatial and temporal distribution of protected species interactions were documented.

植物血红蛋白基因及植物凝集素基因转化水稻的研究

植物血红蛋白在共生固氮根瘤中主要是对固氮酶进行嫌氧保护，确保固氮酶活性，在植物根中协助氧的运输或作为感觉氧压的信号分子．豆科植物凝集素功能之一是对相应专一的根瘤菌有识别作用，并有利于根瘤菌的聚集和侵染。本论文将非豆科结瘤植物Parasponia andersonii血红蛋白基因及豌豆凝集索基因转入水稻，目的是此二基因表达后，豌豆凝集素可聚集、识别豌豆根瘤菌，并有助于它们的侵染，血红蛋白则可对根瘤菌固氮酶进行嫌氧保护，保障其发挥固氮作用，从而为实现水稻结瘤和固氮打下初步基础。 本论文将带有Parasponia血红蛋白基因的pL305质粒，带有潮霉素磷酸转移酶基因及Parasponia血红蛋白基因的农杆菌双元载体质粒pLX412-Hb用花粉管通道法转化水稻l用pLX412-Hb和带有Bar基因、豌豆凝集素基因、Parasponia血红蛋白基因的质粒pLHB用基因枪法转化水稻幼胚及愈伤组织，带有pLX412-Hb的Agrobactmum tumefaciens LBA4404转化烟草，得到如下结果： 1．用pL305质粒花粉管通道法转化水稻，运作1512朵花，得到707粒种子．将230粒种子萌发，发芽220粒;白化苗4株，成苗206株;计发芽率96%，白化苗率1.7%，成苗率90%。取120株提取DNA以Parasponia血红蛋白基因为探针进行点杂交，有6株为阳性结果，阳性率5%．再取4株DNA点杂交阳性植株DNA，以Parasponia血红蛋白基因为探针进行Southem杂交，有3株有阳性结果，阳性率为75%，照此推算转化植株约占总植株的4%．目前，这些转基因植株已开花结实。 2．用pLX412-Hb质粒花粉管通道法转化水稻，运作743朵花，得到340粒种子。将120粒种子萌发，发芽117粒，白化苗3株，成苗111株;计发芽率97. 5%，白化苗率2. 5%，成苗率92. 5%．取30株提取DNA以Parasponia血红蛋白基因为探针进行点杂交，有4株为阳性结果，阳性率13%。再取4株DNA点杂交呈阳性的植株DNA，以Parasponia血红蛋白基因为探针进行Southern杂交，有2株有阳性结果，阳性率为50%，照此推算转化植株约占总植株的7%。目前部分转基因植株巳开花结实． 3.用pLX412 - Hb质粒基因枪法转化水稻幼胚及愈伤组织，抗性筛选得到15株再生植株，以Parasponia血红蛋白基因为探针进行点杂交，有14株为阳性结果，阳性率93%．取7株DNA点杂交呈阳性的植株DNA，以Parasponia血红蛋白基因为探针进行Southern杂交，都为阳性结果，阳性率为100%，照此推算转化植株约占总植株的93%．目前，部分转基因植株已开花结实． 4．用pLX412 -Hb质粒通过Agrobacterrum tumeFaciens LBA4404转化烟草，抗性筛选得到的再生植株以Parasponia血红蛋白基因为探针进行Southern杂交，结果为阳性． 5．用pLHB基因枪法转化的愈伤组织，抗性筛选得到已分化出绿芽点的愈伤组织，以Parasponia血红蛋白基因为探针或以豌豆凝集素基因为探针进行Southern杂交，杂交结果均为阳性． 6．最近国外巳发现大麦有血红蛋白基因．本论文以大麦血红蛋白cDNA为探针对未转基因的水稻进行Southern杂交，结果有阳性带。说明水稻有与大麦血红蛋白基因高度同源序列。以Parasponia血红蛋白基因为探针时杂交结果为阴性，说明水稻血红蛋白基因与Parasponiaa血红蛋白基因核苷酸序列相差较大． 7．提取Southern杂交证明有Parasponia血红蛋白基因整合的水稻根及叶总RNA，以Parasponia血红蛋白基因cDNA为探针进行RNA点杂交，结果根总RNA为阳性，叶总RNA为阴性。初步证明Parasponia血红蛋白基因在水稻根中表达。 8．提取未转基因的水稻根及叶RNA，以大麦血红蛋白基因cDNA为探针进行RNA点杂交，结果：根总RNA为阳性结果，叶总RNA为阴性结果．初步证明水稻血红蛋白基因在水稻根中表达。 总之，本论文证明已将Parasponia血红蛋白基因整合进水稻植株染色体，将豌豆凝集素基因、Parasponia血红蛋白基因整合进水稻愈伤组织染色体，初步证明水稻有血红蛋白基因，内外源血红蛋白基因都有组织特异性表达，从而为本研究的战略设想奠定初步基础。

Effects of density-dependence and sea surface temperature on interannual variation in length-at-age of chub mackerel (Scomber japonicus) in the Kuroshio-Oyashio area during 1970–1997

Annual mean fork length (FL) of the Pacific stock of chub mackerel (Scomber japonicus) was examined for the period of 1970–97. Fork length at age 0 (6 months old) was negatively correlated with year-class strength which fluctuated between 0.2 and 14 billion in number for age-0 fish. Total stock biomass was correlated with FL at age but was not a significant factor. Sea surface temperature (SST) between 38–40°N and 141–143°E during April–June was also negatively correlated with FL at age 0. A modified von Bertalanffy growth model that incorporated the effects of population density and SST on growth was well fitted to the observed FL at ages. The relative FL at age 0 for any given year class was maintained throughout the life span. The variability in size at age in the Pacific stock of chub mackerel is largely attributable to growth during the first six months after hatching.

Age and growth of the swordfish (Xiphias gladius L.) in the waters around Taiwan determined from anal-fin rays

Age and growth of the swordfish (Xiphias gladius) in Taiwan waters was studied from counts of growth bands on cross sections of the second ray of the first anal fin. Data on lower jaw fork length and weight, and samples of the anal fin of male and female swordfish were collected from three offshore and coastal tuna longline fishing ports on a monthly basis between September 1997 and March 1999. In total, 685 anal fins were collected and 627 of them (293 males and 334 females) were aged successfully. The lower jaw fork lengths of the aged individuals ranged from 83.4 to 246.6 cm for the females and from 83.3 to 206 cm for the males. The radii of the fin rays and growth bands on the cross sections were measured under a dissecting microscope equipped with an image analysis system. Trends in the monthly marginal increment ratio indicated that growth bands formed once a year. Thus, the age of each fish was deter-mined from the number of visible growth bands. Two methods were used to estimate and compare the standard and the generalized von Bertalanffy growth parameters for both males and females. The nonlinear least square estimates of the generalized von Bertalanffy growth parameters in method II, in which a power function was used to describe the relationship between ray radius and LJFL, were recommended as most acceptable. There were significant differences in growth parameters between males and females. The growth parameters estimated for females were the following: asymptotic length (L∞) = 300.66 cm, growth coefficient (K) = 0.040/yr, age at zero length (t0) = –0.75 yr, and the fitted fourth parameter (m) = –0.785. The growth parameters estimated for males were the following: asymptotic length (L∞) = 213.05 cm, growth coefficient (K) = 0.086/yr, age at zero length (t0) = –0.626 yr, and the fitted fourth parameter (m) = –0.768.