Lipid, fatty acid and protein utilization during lecithotrophic larval development of Lithodes santolla (Molina) and Paralomis granulosa (Jacquinot)

During the larval development of the subantarctic king crab, Lithodes santolla, and stone crab, Paralomis granulosa, we compared changes in the carbon, fatty acid and protein contents of larvae reared under constant conditions from hatching to metamorphosis, either in presence or absence of food (Artemia spp. nauplii). In both species the feeding condition had no influence on any of the chemical parameters studied, indicating a fully lecithotrophic (i.e. non-feeding) mode of development from hatching of the first zoea to metamorphosis of the late megalopa. Dry mass and carbon contents at hatching were similar in the larvae of both species, but L. santolla contained initially higher total amounts of fatty acids and protein than P. granulosa. Both species utilized considerable portions of their total fatty acid pool which decreased logarithmically throughout the time of development. At metamorphosis, it was almost exhausted in P. granulosa, while L. santolla had consumed only about 60%. Protein utilization, in contrast, was higher in L. santolla (40%) than in P. granulosa (20%). Triacylglycerol was the principal storage lipid in both species, accounting initially for about 75% of the lipid fraction; it was strongly utilized during larval development. Phospholipid constituted the second largest lipid class; it also decreased in P. granulosa, but to a lesser extent in L. santolla. The major fatty acids of both species were 18:1(n−9), 20:5(n−3) and 16:0 as well as, in lower proportions, 18:1(n−7), 22:6(n−3), 16:1(n−7) and 18:0. Monounsaturated fatty acids represented the dominant group in L. santolla, whereas P. granulosa contained similar amounts of mono- and polyunsaturated fatty acids. In L. santolla, monounsaturated fatty acids, especially 16:1(n−7), were preferentially utilized as compared to polyunsaturates. Due to a particularly strong lipid utilization in P. granulosa, all individual fatty acids were largely depleted at metamorphosis, showing similar extents of consumption. L. santolla had higher initial lipid and protein stores that seem to be used more economically as compared to P. granulosa.     

Pelagic swarms and beach strandings of the squat lobster Munida gregaria (Anomura: Munididae) in the Beagle Channel, Tierra del Fuego

The present article is the first formal record of pelagic swarms and beach strandings of the squat lobster Munida gregaria in the Beagle Channel, southern South America. To describe size composition and natural diet of beach strandings and swarms, samples from strandings were taken in April 2007, March 2008 and March 2010. Samples from swarms were taken in May 2007 and April 2010. Also, during November 2008 and January 2009, two acoustic surveys were carried out to describe both, horizontal distribution and school metrics of swarms. Pelagic swarms and beach strandings were composed of 100% individuals of the morph gregaria of M. gregaria. Mean size of males and females in both, beach strandings and swarms, were similar. The diet of pelagic M. gregaria was composed mainly of crustaceans, unicellular algae and small macroalgae, sediment and particulate organic matter. Swarms of pelagic Munida took the shape of extended layers of varying density and height. Their positions in the water column were also variable: swarms were found at different depths, from the subsurface layer to near the sea bottom. Occasionally, some large swarms occupied most of the water column. In the Beagle Channel, SW winds during spring tides could be a forcing factor for M. gregaria strandings. The absence of shoaling animals in the Beagle Channel between 1997 and 2002 and the recent occurrence of swarms are coincident with their appearance in other locations in Patagonia. In consequence, we hypothesize that the factor influencing the formation of swarms must be acting at a regional scale.     

Within‐plant distribution of 1,4‐benzoxazin‐3‐ones contributes to herbivore niche differentiation in maize

Plant defences vary in space and time, which may translate into specific herbivore‐foraging patterns and feeding niche differentiation. To date, little is known about the effect of secondary metabolite patterning on within‐plant herbivore foraging. We investigated how variation in the major maize secondary metabolites, 1,4‐benzoxazin‐3‐one derivatives (BXDs), affects the foraging behaviour of two leaf‐chewing herbivores. BXD levels varied substantially within plants. Older leaves had higher levels of constitutive BXDs while younger leaves were consistently more inducible. These differences were observed independently of plant age, even though the concentrations of most BXDs declined markedly in older plants. Larvae of the well‐adapted maize pest Spodoptera frugiperda preferred and grew better on young inducible leaves irrespective of plant age, while larvae of the generalist Spodoptera littoralis preferred and tended to grow better on old leaves. In BXD‐free mutants, the differences in herbivore weight gain between old and young leaves were absent for both species, and leaf preferences of S. frugiperda were attenuated. In contrast, S. littoralis foraging patterns were not affected. In summary, our study shows that plant secondary metabolites differentially affect performance and foraging of adapted and non‐adapted herbivores and thereby likely contribute to feeding niche differentiation.     

The role of the predator Trophon geversianus in an intertidal population of Mytilus chilensis in a rocky shore of the Beagle Channel,Tierra del Fuego,Argentina

Predation influences changes in the abundance and the limits of spatial distribution of organisms on rocky shores. We quantified the effect of the predation pressure of the gastropod Trophon geversianus on the mytilid Mytilus chilensis in a rocky intertidal community of the Beagle Channel, Tierra del Fuego. We quantified the density of T. geversianus along with the density of T. geversianus preying on M. chilensis and examined the potential relationship between sizes of both T. geversianus and M. c hilensis. Additionally, we carried out laboratory experiments to quantify the drilling and ingestion rates of T. geversianus on M. c hilensis at different aerial exposure times. At mid intertidal levels, unlike at low intertidal levels, T. geversianus consumed more frequently the available size range of mussels. On average, sizes of predator and prey consumed were positively correlated. The drilling rate decreased with increasing time of aerial exposure. Additionally, permanently submerged predators invested less time consuming the same amount of food than individuals exposed for 4 out of 12?h (4/12?h). Predators exposed for 9/12?h invested less time and consumed less food than those exposed 4/12?h. Our results suggest that T. geversianus is an efficient predator of M. chilensis, due to both its high density and feeding rate. Our results suggest that the strong predation pressure of T. geversianus on M. chilensis prevents this key competitor from monopolizing space at the low level through controlling their abundance, and further limits their vertical distribution.     

氨氯地平联合依那普利治疗原发性高血压的临床疗效及对患者左心室肥厚的影响

摘要目的：探讨氨氯地平联合依那普利治疗原发性高血压的临床效果,观察联合用药对左心室肥厚的影响。方法：选择本院收治的原发性高血压患者92例,随机分为观察组和对照组,各46例,对照组给予苯磺酸左旋氨氯地平5mg,1次／d,口服;观察组在对照组基础上加用马来酸依那普利10mg,2次／d,口服,疗程均为24周。观察两组治疗前后血压变化,应用超声心动图测量两组左心室厚度变化。结果：治疗后,观察组总有效率为91_3％;对照组总有效率为73．9％,观察组总有效率高于对照组（P〈0．05）。治疗前两组心率、血压比较无统计学差异（P〉0．05）,治疗后两组血压均明显降低,观察组收缩压、舒张压明显低于对照组（P〈O．05）;观察组心率明显低于对照组（P〈0．01）。治疗前两组左心室舒张末期室间隔厚度（Leaventricularend—diastolicventricularseptalthickness,IVST）、左心室后壁厚度（1eftventricularposteriorwallthickness,U,PwT）和左室射血分数（Leftventricularejectionfxaction,LVEF）比较无统计学差异（P〉0．05）;治疗后观察组IVST、L、,PwT明显低于对照组,LVEF明显高于对照组（P〈0．05）。结论：氨氯地平联合依那普利治疗原发性高血压能有效扭转左心室肥厚,降压效果较单独应用氨氯地平更佳。     

Physiological methods to study biofilm disinfection

This report reviews the development of a rapidin situ approach to study the physiological responses of bacteria within biofilms to disinfectants. One method utilized direct viable counts (DVC) to assess the disinfection efficacy when thin biofilms were exposed to chlorine or monochloramine. Results obtained using the DVC method were one log higher than plate count (PC) estimates of the surviving population after disinfection. Other methods incorporated the use of fluorogenic stains, a cryotomy technique to yield thin (5-m) sections of biofilm communities and examination by fluorescence microscopy. The fluorogenic stains used in this approach included 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), which indicates cellular electron transport activity and Rhodamine 123, which responds specifically to proton motive force. The use of these stains allowed the microscopic discrimination of physiologically active bacteria as well as heterogeneities of active cells within thicker biofilms. The results of experiments using these techniques with pure culture and binary population biofilms on stainless steel coupons indicated biocidal activity of chlorine-based disinfectants occurred initially at the bulk-fluid interface of the communities and progressed toward the substratum. This approach provided a unique opportunity to describe the spatial response of bacteria within biofilms to antimicrobial agents and address mechanisms explaining their comparative resistance to disinfection in a way that has not been possible using traditional approaches. Results obtained using this alternative approach were also consistently higher than PC data following disinfection. These observations suggest that traditional methods involving biofilm removal and bacterial enumeration by colony formation overestimate biocide efficacy. Hence the alternative approach described here more accurately indicates the ability of bacteria surviving disinfection to recover and grow as well as demonstrate spatial heterogeneities in cellular physiological activities within biofilms.     

Spermatogenesis in the archaic hydrothermal vent bivalve,Bathypecten vulcani,and comparison of spermatozoon ultrastructure with littoral pectinids

Summary

Bathypecten vulcani is considered a relict species from the Paleozoic, based on shell characteristics such as the presence of calcite prisms. To date, it is the only pectinid species reported from hydrothermal ecosystems. Histological and ultrastructural studies show that spermatogenesis is identical to that of littoral pectinids. The spermatozoon has a 2.7 μm long pyriform head and a 40 μm flagellum. The four mitochondria of the mid-piece are about 1.2 μm in diameter. The nucleus contains dense chromatin fibres and possesses a wide, shallow (0.1 μm) anterior fossa and a narrow, deeper (0.2 μm) posterior nuclear fossa. Comparison of the ultrastructural characteristics of the spermatozoon of B. vulcani with those of littoral pectinids shows that they can be used as a diagnostic feature of this species. In particular, its acrosome characters will be a useful complement to the shell characters in the study of the phylogenetic position of this species in relation to other pectinids.