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1.
Durophagous predation on scaphitid ammonoids in the Late Cretaceous Western Interior Seaway of North America
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Yusuke Takeda Kazushige Tanabe Takenori Sasaki Neil H. Landman 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2016,49(1):28-42
This study is the first to report a trend of predation intensity on scaphitid ammonoids from the Turonian to the Maastrichtian (Late Cretaceous) on the basis of analysis of ventral shell breakage in large samples from the US Western Interior Province. Analysis of 835 adult specimens revealed ventral shell breakage in 50 specimens. In most of the damaged specimens, the breakage occurred in a preferred position at the rear part of the body chamber. Ventral breakage is rare in the Turonian specimens, whereas it is common in the Campanian and Maastrichtian specimens. The shell diameter of adult scaphitid ammonoids tends to increase with time. The position of the breakage and the absence of repairs indicate that the ventral breakage resulted from lethal predation. Based on the incidence of breakage and the size and shape of the breaks, possible predators include fish, reptiles and cephalopods such as Placenticeras, Eutrephoceras and coleoids. Our statistical analysis of ventral shell breakage indicates that the incidence of lethal predation increased in conjunction with an increase in adult shell size, suggesting that the body size of the prey was an important factor in predator–prey interactions. In addition, the predatory damage is more extensive in larger adults. 相似文献
2.
《Cytotherapy》2014,16(11):1590-1594
Background aimsAlthough umbilical cord blood (UCB) has now become a common stem cell source, UCB bag breakage is a known risk in UCB transplantation (UCBT). This survey provides the first comprehensive data on the frequency and causes of UCB bag breakage in Japan.MethodsData regarding UCB bag breakage from all causes, identified between April 1, 2010, and September 3, 2013, were collected from all transplant centers registered for UCBT (209 hospitals) and all public cord blood banks (CBBs) (8 CBBs) in Japan.ResultsSeventeen incidents of UCB bag breakage at CBBs were confirmed, none of which resulted in bags being shipped to transplant centers. From among 3836 UCBT, 16 incidents (0.4%) of UCB bag breakage were confirmed at transplant centers. Although all these bags were used for transplantation, no direct health hazard was reported. The major cause of UCB bag breakage confirmed at transplant centers was considered to be external force (75%). In addition, 11 incidents of unexplained UCB bag breakage at sealing between compartments were reported.ConclusionsUCB bag breakage was confirmed at both CBBs and transplant centers. UCB bags should be handled with particular care and attention. 相似文献
3.
Whereas most plants are flexible structures that undergo large deformations under flow, another process can occur when the plant is broken by heavy fluid-loading. We investigate here the mechanism of such possible breakage, focusing on the flow-induced pruning that can be observed in plants or aquatic vegetation when parts of the structure break under flow. By computation on an actual tree geometry, a 20-yr-old walnut tree (Juglans Regia L.) and comparison with simple models, we analyze the influence of geometrical and physical parameters on the occurrence of branch breakage and on the successive breaking events occurring in a tree-like structure when the flow velocity is increased. We show that both the branching pattern and the slenderness exponent, defining the branch taper, play a major role in the breakage scenario. We identify a criterion for branch breakage to occur before breakage of the trunk. In that case, we show that the successive breakage of peripheral branches allows the plant to sustain higher flow forces. This mechanism is, therefore, similar to elastic reconfiguration, and can be seen as a second strategy to overcome critical events, possibly a widespread solution in plants and benthic organisms. 相似文献
4.
Michele Guidone Carol Thornber Brian Wysor Charles J. O'Kelly 《Journal of phycology》2013,49(5):979-995
Macroalgal bloom‐forming species occur in coastal systems worldwide. However, due to overlapping morphologies in some taxa, accurate taxonomic assessment and classification of these species can be quite challenging. We investigated the molecular and morphological characteristics of 153 specimens of bloom‐forming Ulva located in and around Narragansett Bay, RI, USA. We analyzed sequences of the nuclear internal transcribed spacer 1 region (ITS1) and the chloroplast‐encoded rbcL; based on the ITS1 data, we grouped the specimens into nine operational taxonomic units (OTUs). Eight of these OTUs have been previously reported to exist, while one is novel. Of the eight OTUs, all shared sequence identity with previously published sequences or differed by less than 1.5% sequence divergence for two molecular markers. Previously, 10 species names were reported for Ulva in Rhode Island (one blade and nine tube‐forming species) based upon morphological classification alone. Of our nine OTUs, three contained blade‐forming specimens (U. lactuca, U. compressa, U. rigida), one OTU had a blade with a tubular stipe, and six contained unbranched and/or branched tubular morphologies (one of these six, U. compressa, had both a blade and a tube morphology). While the three blade‐forming OTUs in Narragansett Bay can frequently be distinguished by careful observations of morphological characteristics, and spatial/temporal distribution, it is much more difficult to distinguish among the tube‐forming specimens based upon morphology or distribution alone. Our data support the molecular species concept for Ulva, and indicate that molecular‐based classifications of Ulva species are critical for proper species identification, and subsequent ecological assessment or mitigation of Ulva blooms. 相似文献
5.
Kira A. Krumhansl J. Michael Lee 《Journal of experimental marine biology and ecology》2011,407(1):12-18
Increased breakage of macroalgal fronds during large wave events can significantly reduce canopy cover and biomass. We examined the effects of encrustation by the invasive bryozoan Membranipora membranacea and damage by the snail Lacuna vincta on the ability of kelp blades (Saccharina longicruris, Laminaria digitata, and Laminaria complanata) to withstand wave forces. Using standard materials testing procedures, we documented significant reductions in the maximum stress before breakage, toughness, and extensibility of blade material following bryozoan encrustation. Histological sections of blade tissue indicated a significant degradation of the outer layers of cells following prolonged encrustation by M. membranacea as a likely cause of weakening. Full-thickness perforations and partial-thickness grazing scars also reduced blade strength, suggesting that grazing damage can initiate cracks that lead to blade breakage. Our findings provide a mechanistic link between the damaging effects of mesograzers and encrusting bryozoa on their algal hosts and the export of detrital material from subtidal kelp beds. 相似文献
6.
《Plains anthropologist》2013,58(33):201-203
AbstractAn analysis of differential breakage in a sample of Clovis, Agate Bas in and Folsom points suggests that the Clovis form is the most resistant to breakage and the fluted Folsom type the most fragile. 相似文献
7.
A paleoenvironmental study of the dasyclad Mizzia Schubert, 1907 is potentially important because, unlike most of the other fossil reef-dwelling organisms found in the Guadalupe Mountains, the fossil Mizzia (restricted to the Permian) has a modern analog, Cymopolia Lamouroux, 1916 (Cretaceous to Holocene). The overall morphology of the two genera is similar: both are articulated, and observations on our specimens suggest that both were branched. The transition from the remarkably high-diversity sponge and algal assemblage in the reef into the remarkably low-diversity dasyclad-dominated assemblage in the back reef is abrupt, occurring over distances as short as 10 m. Mizzia is the dominant and usually the only component in grainstones, packstones, and wackestones found; immediately shelfward of the Capitan reef. The low percentage of broken segments (average 10%) and the discovery of several intact sections of thallus are evidence against wave action as a possible limiting factor. Because the climate in the Guadalupe Mountains was extremely arid and because dasyclads are euryhaline, hypersalinity is considered the most likely limiting factor in this case. Our conclusion that prolific stands of dasyclads formed in shallow protected lagoons immediately behind an emergent barrier reef is not compatible with the currently accepted marginal mound hypothesis for deposition of the Capitan reef complex. We suggest that the marginal mound model must either be modified or abandoned in favor of the originally proposed barrier reef model of deposition. 相似文献
8.
M D Russell 《American journal of physical anthropology》1987,72(3):373-379
The fragmentary condition of the Krapina Neandertal remains has been offered as one line of evidence for the hypothesis that these hominids were the victims of cannibals seeking marrow and brains. Two other hypotheses regarding the causes of the framentation have been raised: a substantial portion of the breakage in the Krapina collection is attributable to excavation damage; and the rest of the breakage is attributable to sedimentary pressure and to natural rock falls that occurred during the site's prehistory. The purpose of this paper is report on tests of these three hypotheses concerning the cause of breakage in the Krapina material. Microscopic inspection of all Krapina hominid specimens showed that 23% of the material was inadvertantly broken during excavation or during quarrying that took place at the end of the last century. The morphology of the prehistoric breakage is inconsistent with the cannibalism hypothesis and supports the hypothesis that prehistoric breakage was caused by sedimentary pressure and/or roof falls. 相似文献
9.
《Plains anthropologist》2013,58(69):175-185
AbstractEvidence of a late prehistoric and protohistoric blade technology has been found at a number of sites on the central and southern Texas coast. Blades and cores from two major sites, Kirchmeyer and Indian Island, are described in detail. Wear pattern analyses of the materials indicate that laterally-trimmed blades functioned as cutting tools or knives. Methods used in blade production are examined, and the possible causes for the development of the blade technology are explored. 相似文献
10.
Quantitative coral damage assessment by means of line transects was performed in several northern Red Sea coral reef sites in Israel (Eilat) and Egypt (Hurghada area). Reefs with high and low visitor frequency were compared. For both reef systems, breakage was found to be the most common damage category, being significantly higher on highly frequented reefs. Also, all observed damage (breakage, tissue loss, algal overgrowth) was most frequent within the first ten meters depth. A significant difference in the amount of corals overgrown by algae was found on the reefs near Hurghada as compared to all other reefs. Algal overgrowth was correlated with the occurrence of tissue loss and breakage, being considered as a consequence of pollution or the former damage types. In all cases of damage, Acropora was the most frequently affected genus, while Millepora dichotoma was the most affected species. 相似文献
11.
Summary. The little-known flower mantis genus Heliomantis Giglio-Tos 1915 (Hymenopodidae) distributed in South and South-Eastern Asia is revised. All species are redescribed. New data on the morphology, distribution and ecology are given, and all known specimens are listed. The lectotype of H. elegans (Navás 1904) is designated. Due to highly divergent morphology, H. latipennis Werner 1930 from Sarawak, Borneo, is transferred to Werneriana n. gen., leaving the genus Heliomantis with the only species, H. elegans (Navás, 1904). 相似文献
12.
《Plains anthropologist》2013,58(96):125-135
AbstractAnalysis of artifacts recovered from the Moe site located in northwestern North Dakota reveals the presence of 15 blades and three blade-like flakes, the majority of which are made of Knife River Flint and have been modified by retouch flaking. A comparison of the Moe specimens to those from the Pelland site in northern Minnesota, the only other site from the study area which contains blades of Paleo-Indian age, indicates that the Moe specimens are smaller in all dimensions. The Pelland specimens are made of Knife River Flint and have been modified by retouch flaking. Examination of the literature on Paleo-Indian sites from the Plains region indicates that blade production is more common in Plano cultures particularly Agate Basin and Plainview-Goshen than in earlier Clovis or Folsom cultures or later Cody cultures. It is suggested that the Pelland and Moe site blades are Plano in age and most likely Agate Basin or Plainview-Goshen in cultural affiliation. A model provided by Leo Pettipas (1976) is used to suggest an eastward movement of Plains Plano cultures using Knife River Flint across southern Manitoba, eastern North Dakota, and into western and northern Minnesota following the recession of Glacial Lake Agassiz. 相似文献
13.
BackgroundThe National Institutes of Health (NIH) category IV prostatitis is a painless prostate gland inflammation, just as its name implies, this type of prostatitis is related with inflammation of the prostate, but most men are not conscious of it. However, category IV prostatitis is fairly common in general populations and reported having indirect relationships with prostate cancer.MethodWe analyzed the concentration of zinc (Zn), copper (Cu), calcium (Ca) and magnesium (Mg) in expressed prostatic secretion (EPS) and serum of patients with category IV prostatitis and healthy controls, investigating the diagnostic potential of different metals in category IV prostatitis using a flame atomic absorption spectrometer (FAAS).ResultsMetal concentration combined clinical characteristics analysis suggested that average level of Zn, Ca, Mg were significantly lower in the EPS of patients with category IV prostatitis (P-value< 0.000), while Cu level raised obviously (P-value< 0.000). And in the serum, mean concentrations of Ca was also found to increase significantly in the patients with category IV prostatitis compared to healthy controls. Moreover, the correlation analysis indicated that age showed a positive correlation with EPS Zn, Ca, Mg concentration (P-value< 0.05), while albumin correlates with EPS Zn, Ca, Mg concentration reversely (P-value< 0.05) in patients with category IV prostatitis.ConclusionOur report revealed that determination of the metal elements zinc, copper, calcium and magnesium in the serum and EPS could be a new and promising strategy for the rapid diagnosis of category IV prostatitis. 相似文献
14.
Marc Verlaque 《Plant biosystems》2013,147(1-2):29-39
Abstract Studies on the genus Peyssonnelia (Rhodophyceae). X. Presence of Peyssonnelia codana (Rosenvinge) Denizot in the Mediterranean.—Peyssonnelia codana (Rosenvinge) Denizot, previously known only from Denmark, is recorded from the vicinity of a thermal power plant outlet (Martigues-Ponteau, Gulf of Fos, France). Mediterranean specimens are described and new details about the morphology of sporangial and sexual nemathecia are given. 相似文献
15.
Distinguishing leporid bones accumulated by different agents such as diurnal raptors, owls, mammals and humans is essential to gain an understanding of not only human subsistence activities but also past ecology. This is particularly relevant in Iberian Palaeolithic sites where leporid remains usually constitute the most abundant taxon. Among diurnal raptors the Spanish Imperial eagle (Aquila adalberti) has been one of the most important leporid predators throughout the Iberian Peninsula. In order to investigate the taphonomic signature of this raptor, rabbit remains from 79 pellets were examined. Results show a high proportion of distal elements of the limb bones and skull. Compared with other diurnal birds of prey, the assemblages produced by this species appear to show a higher degree of breakage and corrosion from digestion. These results place this predator within a category similar to the small mammal carnivores (category 5) in terms of skeletal element abundance, breakage and digestion. It is hoped that these data will enable analysts to identify leporid fossils accumulated by the Spanish Imperial Eagle in archaeological assemblages. 相似文献
16.
Sedimentation Coefficient and Fragility under Hydrodynamic Shear as Measures of Molecular Weight of the DNA of Phage T5
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T5 DNA molecules resemble fragments of T2 DNA of molecular weight 84 × 106 with respect to sedimentation coefficient and susceptibility to breakage under hydrodynamic shear. The sedimentation coefficient falls by the same factor when either T2 or T5 DNA is broken at its characteristic critical shear rate. At a given high rate of shear, both DNA's are broken into fragments exhibiting the same sedimentation coefficient. It follows that 84 × 106 is a proper estimate of the molecular weight of T5 DNA, and that particles of phage T5, like those of T2, contain a single DNA molecule. 相似文献
17.
Heather E. Johnson Vernon C. Bleich Paul R. Krausman John L. Koprowski 《European Journal of Wildlife Research》2007,53(1):9-15
Although antler size has been identified as a primary determinant of dominance, fighting success, and reproductive success
in male cervids, >80% of the male tule elk (Cervus elaphus nannodes) in the Owens Valley, California, experience antler breakage. To determine the effect of antler breakage on male mating success,
we recorded antler morphology, body size, and mating behavior of male elk throughout the rut. Antler breakage, regardless
of severity, had no effect on male–male assessment, fighting success, or harem-holding status. The factor consistently associated
with our indices of male mating success was not antler size but body size. Although antler size is frequently emphasized as
a key factor in male dominance and social rank, this association may reflect the correlation between antler size and body
size. In the Owens Valley, it appears that male elk are not assessing competitors based on antler morphology but on other
characteristics.
An erratum to this article can be found at 相似文献
18.
M. Kosloski 《Journal of experimental marine biology and ecology》2011,396(2):115-121
The ability to assign lethal traces left on prey to particular durophagous predators enhances our understanding of predation pressure in the fossil record. To determine whether stone crabs (Menippe mercenaria Say 1818) leave diagnostic traces in the act of feeding on hard clams (Mercenaria mercenaria Linnaeus 1758), live clams were offered to crabs in laboratory aquaria over several months and the fragments produced during predation were examined for diagnostic breakage patterns. These fragments were then compared both macroscopically and using scanning electron microscopy to the fracture patterns produced by tumbling clams in a rock tumbler which simulated breakage during transport in the surf zone, and crushing clams using an Instron which simulated breakage resulting from sediment compaction. Fossil specimens of Mercenaria mercenaria were also examined to determine whether the criteria for recognizing predation traces generated experimentally could be recognized. While not all acts of predation produce diagnostic traces, when larger fragments (greater than 50% shell remaining) are produced during feeding, predatory-diagnostic breakage ranges from 70 to 80%. Macroscopic breakage patterns generated during the predation experiments were also present in fossil specimens. Damage caused by abiotic mechanisms (tumbling and crushing) is highly unlikely to be confused with damage produced by this predator. 相似文献
19.
The phylogenetic and systematic position of all species of Acer section Acer from North America, East Asia, and western Eurasia are evaluated using various splits-based networks (distance networks,
bipartition networks), ITS motif analysis, and morphology. Molecular analyses are based on 276 ITS clones obtained from 101
specimens collected mainly from natural stands. The large sample size ensures to cover sufficiently inter- and intraspecific
ITS variability of this group. Formerly recognised species are generally supported by ITS data and morphology; the combination
of molecular (ITS) and morphological criteria allows defining seven (supraspecific) taxonomic groups prior to a phylogenetic
reconstruction. Phylogenetic signals captured in modern ITS sequences are partly incompatible but clearly suggest that Acer section Acer underwent three major radiations. Horizontal gene flow is indicated between ancestors of extant taxa that are isolated at
present times. The level of ITS derivation can be estimated and corresponds to levels of morphological differentiation and
(palaeo-) biogeographical patterns. Based on our results we question the potential of cladistic approaches to infer low-level
evolution in an adequate manner and demonstrate that speciation in members of Acer section Acer is not generally linked to cladogenesis. The data and methodologies provided here allow to trace pathways of low-level evolution
and to analyse such data sets with a less restricted (non-dichotomous) dynamic concept.
Electronic Supplementary Material Supplementary material is available in the online version of this article at 相似文献
20.
K. Gopalkrishnan 《Journal of biosciences》1998,23(5):613-616
Motility disorders due to tail defects are often seen in clinical andrology. Sperm motility should be assessed with regard
to the morphology of the flagellum. Since suitable longitudinal sections are rarely obtained by routine transmission electron
microscopy (TEM) and in view of the importance of dense fibres in modulating sperm motility and providing tensile strength, a detailed, study
of human sperm flagellum by negative staining andTEM was attempted. The study was undertaken in two groups of men (I) fertile and (II) asthenozoospermic. The study revealed that outer dense fibres extend to 50–60% of the principal piece. Normal dense fibres
were seen in 83% sperms and 23% sperms in groupsI andII respectively. The characteristics seen were variation in diameter, breakage or degradation with lacking or extended endpiece.
The negative staining method provides an easy and useful analytical tool for identifying the defects of dense fibres and quantifying
them. 相似文献