Age validation of juvenile Shortfin Mako (Isurus oxyrinchus) tagged and marked with oxytetracycline off southern California

The purpose of this study was to validate aging results of juvenile Shortfin Mako (Isurus oxyrinchus) by vertebral band counts. Vertebrae of 29 juvenile Shortfin Mako marked with oxytetracycline (OTC) were obtained from tag-recapture activities to determine centrum growth-band deposition. Tagging occurred off southern California from 1996 to 2010, and time at liberty of the 29 sharks ranged from 4 months to 4.4 years (mean=1.3 years). Growth information also was obtained from length-frequency modal analyses (MULTIFAN and MIXDIST) by using a 29-year data set of commercial and research catch data, in addition to a tag-recapture growth model (e.g, the GROTAG model). For vertebrae samples used for age validation, shark size at time of release ranged from 79 to 142 cm fork length (FL) and from 98 to 200 cm FL at recapture. Results from band counts of vertebrae distal to OTC marks indicate 2 band pairs (2 translucent and 2 opaque) are formed each year for Shortfin Mako of the size range examined. Length-frequency analyses identified 3 age class modes. Growth rate estimates from 26.5 to 35.5 cm/year were calculated for the first age-class mode (85 cm FL) and from 22.4 to 28.6 cm/year for the second age-class mode (130 cm FL). Results from the tag-recapture growth model revealed fast growth during time at liberty for tagged fish of the 2 youngest age classes. Collectively, these methods suggest rapid growth of juvenile Shortfin Mako in the southern California study area and indicate biannual deposition of growth bands in vertebrae for the first 5 years.

A bone remodelling model coupling micro-damage growth and repair by 3D BMU-activity.

Bone as most of living tissues is able, during its entire lifetime, to adapt its internal microstructure and subsequently its associated mechanical properties to its specific mechanical and physiological environment in a process commonly known as bone remodelling. Bone is therefore continuously renewed and micro-damage, accumulated by fatigue or creep, is removed minimizing the risk of fracture. Nevertheless, bone is not always able to repair itself completely. Actually, if bone repairing function is slower than micro-damage accumulation, a type of bone fracture, usually known as "stress fracture", can finally evolve. In this paper, we propose a bone remodelling continuous model able to simulate micro-damage growth and repair in a coupled way and able therefore to predict the occurrence of "stress fractures". The biological bone remodelling process is modelled in terms of equations that describe the activity of basic multicellular units. The predicted results show a good correspondence with experimental and clinical data. For example, in disuse, bone porosity increases until an equilibrium situation is achieved. In overloading, bone porosity decreases unless the damage rate is so high that causes resorption or "stress fracture".

Survey and impact assessment of derelict fish traps in St. Thomas and St. John, U.S. Virgin Islands

Since 2001, NOAA National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment’s (CCMA) Biogeography Branch (BB) has been working with federal and territorial partners to characterize, monitor, and assess the status of the marine environment across the U.S. Virgin Islands (USVI). At the request of the St. Thomas Fisherman’s Association (STFA) and NOAA Marine Debris Program, CCMA BB developed new partnerships and novel technologies to scientifically assess the threat from derelict fish traps (DFTs). Traps are the predominant gear used for finfish and lobster harvesting in St. Thomas and St. John. Natural phenomena (ground swells, hurricanes) and increasing competition for space by numerous user groups have generated concern about increasing trap loss and the possible ecological, as well as economic, ramifications. Prior to this study, there was a general lack of knowledge regarding derelict fish traps in the Caribbean. No spatially explicit information existed regarding fishing effort, abundance and distribution of derelict traps, the rate at which active traps become derelict, or areas that are prone to dereliction. Furthermore, there was only limited information regarding the impacts of derelict traps on natural resources including ghost fishing. This research identified two groups of fishing communities in the region: commercial fishing that is most active in deeper waters (30 m and greater) and an unknown number of unlicensed subsistence and or commercial fishers that fish closer to shore in shallower waters (30 m and less). In the commercial fishery there are an estimated 6,500 active traps (fish and lobster combined). Of those traps, nearly 8% (514) were reported lost during the 2008-2010 period. Causes of loss/dereliction include: movement of the traps or loss of trap markers due to entanglement of lines by passing vessels; theft; severe weather events (storms, large ground swells); intentional disposal by fishermen; traps becoming caught on various bottom structures (natural substrates, wrecks, etc.); and human error.

Oogenesis and spawn formation in the invasive lionfish, Pterois miles and Pterois volitans

The Indo-Pacific lionfish, Pterois miles and P. volitans, have recently invaded the U.S. east coast and the Caribbean and pose a significant threat to native reef fish communities. Few studies have documented reproduction in pteroines from the Indo-Pacific. This study provides a description of oogenesis and spawn formation in P. miles and P. volitans collected from offshore waters of North Carolina, U.S.A and the Bahamas. Using histological and laboratory observations, we found no differences in reproductive biology between P. miles and P. volitans. These lionfish spawn buoyant eggs that are encased in a hollow mass of mucus produced by specialized secretory cells of the ovarian wall complex. Oocytes develop on highly vascularized peduncles with all oocyte stages present in the ovary of spawning females and the most mature oocytes placed terminally, near the ovarian lumen. Given these ovarian characteristics, these lionfish are asynchronous, indeterminate batch spawners and are thus capable of sustained reproduction throughout the year when conditions are suitable. This mode of reproduction could have contributed to the recent and rapid establishment of these lionfish in the northwestern Atlantic and Caribbean.

Prey consumption of Steller sea lions (Eumetopias jubatus) off Alaska: How much prey do they require?

The effects of seasonal and regional differences in diet composition on the food requirements of Steller sea lions (Eumetopias jubatus) were estimated by using a bioenergetic model. The model considered differences in the energy density of the prey, and differences in digestive efficiency and the heat increment of feeding of different diets. The model predicted that Steller sea lions in southeast Alaska required 45–60% more food per day in early spring (March) than after the breeding season in late summer (August) because of seasonal changes in the energy density of the diets (along with seasonal changes in energy requirements). The southeast Alaska population, at 23,000 (±1660 SD) animals (all ages), consumed an estimated 140,000 (±27,800) t of prey in 1998. In contrast, we estimated that the 51,000 (±3680) animals making up the western Alaska population in the Gulf of Alaska and Aleutian Islands consumed just over twice this amount (303,000 [±57,500] t). In terms of biomass removed in 1998 from Alaskan waters, we estimated that Steller sea lions accounted for about 5% of the natural mortality of gadids (pollock and cod) and up to 75% of the natural mortality of hexagrammids (adult Atka mackerel). These two groups of species were consumed in higher amounts than any other. The predicted average daily food requirement per individual ranged from 16 (±2.8) to 20 (±3.6) kg (all ages combined). Per capita food requirements differed by as much as 24% between regions of Alaska depending on the relative amounts of low–energy-density prey (e.g. gadids) versus high–energy-density prey (e.g. forage fish and salmon) consumed. Estimated requirements were highest in regions where Steller sea lions consumed higher proportions of low–energy-density prey and experienced the highest rates of population decline

水稻AP2/EREBP转录因子基因OsDRE和OsRAF的功能分析

AP2是一个大的转录因子家族，因其成员含有一个60-70 个氨基酸残基的保守结构域即AP2结构域而得名，它们的功能涉及植物花的发育以及植物对生物或非生物逆境的应答反应。根据它们所含的AP2 结构域的数目，这个家族可分为AP2亚家族和EREBP 亚家族。 AP2亚家族成员含两个AP2结构域，EREBP 亚家族成员含一个AP2结构域。一般来说，AP2 亚家族的成员主要参与植物发育过程的调控;EREBP 亚家族成员则主要参与对逆境的应答反应。按照它们响应外界刺激的类型和AP2结构域中结合顺式作用元件的核心氨基酸的不同，EREBP亚家族又可分为ERF和CBF/DREB两大类群，ERF 类主要响应生物类逆境的诱导，CBF/DREB类则响应干旱、低温等非生物胁迫的刺激。 根据AP2保守结构域搜索，水稻基因组中一共有147个AP2/EREBP成员，但其中功能得到证实的还非常有限。为了解更多AP2基因在植物生长发育过程中的功能，我们先从水稻基因组数据库中搜索到含有AP2/EREBP 结构域的推测基因序列，选择其中40个扩增并成功扩增出31个，将这些DNA片段点在尼龙膜上，然后用水稻叶片cDNA 作模板标记探针，与固定在膜上的推测基因杂交。杂交结果作为选择基因进行功能分析的重要依据。 OsDRE就是我们选择进行研究的一个表达较强的基因。首先，通过RACE 克隆得到OsDRE 的cDNA全长 1589bp，它编码318个氨基酸。Blast 搜索和保守结构域序列比对分析以及进化树分析显示它是一个新的ERF 基因。RT-PCR分析表明该基因在水稻各种组织中表达量比较一致，而且，OsDRE 既不对植物生长物质如乙烯，水杨酸（SA），茉莉酸甲酯（MJ），脱落酸（ABA），赤霉素（GA3），油菜素内酯（BR）的诱导起反应，同样也不响应环境因子如低温、干旱条件的处理。这些结果说明OsDRE是一个不响应胁迫相关因素的诱导的、组成型表达的水稻基因。用OsDRE的非保守区域构建的RNAi 载体转入水稻后未能使转基因水稻产生异常表型，然而，OsDRE在水稻和拟南芥中的过量表达都导致转基因植物出现植株矮小、开花延迟、生长周期延长以及育性降低等表型，说明OsDRE对生长和发育的影响在水稻和拟南芥中是一致的。 基于以上原因，我们选择在遗传分析方面有明显优势的拟南芥作为材料，对OsDRE基因功能进行研究并得出以下结论：（1）瞬时表达和随后的过量表达证明OsDRE定位于细胞核中，过量表达OsDRE引起转基因植株的生长周期变长、抽苔时间延迟和抽苔时莲座叶的数量增多;（2）过量表达OsDRE通过一种不影响细胞数量的方式抑制了细胞的膨胀从而导致植物器官以致整个植株变小，而且，在此过程中部分器官的形态也受到了影响;（3）OsDRE过量表达能激活已知位于乙烯信号途径下游的基因表达并且转基因植株幼苗在黑暗中出现下胚轴及根缩短变粗的现象，提示OsDRE 可能部分参与了乙烯信号途径下游的反应。 除此之外，我们还初步分析了另一个EREBP基因，并将其命名为OsRAF。氨基酸序列分析表明该基因与大麦的RAF 基因在蛋白水平上相似性最高。Northern 杂交结果进一步显示，与RAF 一样，OsRAF 也是根中优势表达的基因，并且它的表达量在乙烯或低温的诱导下增加。对转基因植株的观察和瞬时表达表明OsRAF 定位于细胞核中。 综上所述，对水稻基因OsDRE 和OsRAF的分析表明， OsDRE是一个新的ERF基因，它不受乙烯等因素的诱导并且过量表达该基因导致转基因植株出现细胞膨胀受到抑制等一系列的表型。另外，OsRAF在水稻根中优势表达并受乙烯和低温的诱导，目前，与之相关的功能研究正在进行。