The effect of methanogen growth on mineral substrates: will Ni markers of methanogen‐based communities be detectable in the rock record?

Methanogens, thought to be present on early Earth, have a high requirement for Ni, suggesting that Ni utilization could be a potential biosignature for methanogens if enhanced Ni extraction from surrounding minerals accompanies methanogenic growth. To test the potential for such Ni extraction from minerals by methanogens, Ni release from Ni‐containing silicate glass was measured in Ni‐free growth medium in the presence of the methanogen Methanothermobacter thermoautotrophicus (average pH ∼7.0) and observed to be higher than an abiotic control (average pH ∼6.8). However, batch dissolution experiments and a siderophore assay indicate that cell exudates such as siderophores, low molecular weight organic acids, or lysates accompanying cell death are not responsible for the observed increase in Ni release rate. In addition, scanning electron microscopy (SEM) shows little to no evidence of direct microbe–mineral interactions such as biofilms or pitting. Instead, comparison with abiotic experiments suggests that changes in pH due to CO₂ uptake may be responsible for enhanced dissolution in the presence of metabolizing cells. These results document that methanogens may not preferentially extract Ni from surrounding minerals although they may indirectly affect mineral reaction rates that are pH sensitive. Thus identifiable Ni biosignatures may not exist in the rock record to document the presence of methanogens on early Earth or Mars.     

Multidecadal to millennial-scale shifts in drought conditions on the Canadian prairies over the past six millennia: implications for future drought assessment

Three high-resolution climatic reconstructions, based on diatom analyses from lake sediment cores from the Canadian prairies, show that shifts in drought conditions have prevailed on centennial to millennial time scales for at least the past six millennia. These shifts in mean aridity exhibit broad regional synchrony, with particularly pronounced shifts at all sites between ∼1700–2000 cal. yr bp and ∼3600–3900 cal. yr bp , as well as at ∼5400–5500 cal. yr bp for the two sites which extend back to at least 6000 cal. yr bp . The two Saskatchewan lakes exhibited significant coherence in both the timing and direction of these shifts, whereas inferred changes at the westernmost site in Alberta were significantly correlated to the Saskatchewan sites, but opposite in sign, and exhibited more high-frequency variation on the scale of centuries. The mechanisms behind these abrupt shifts in aridity are poorly understood, but may be linked to changes in oceanic–atmospheric interactions that influence the mean position of the jetstream and the associated storm tracks. Natural shifts in mean climatic conditions may accelerate with increasing carbon dioxide levels intensifying the likelihood of extreme droughts in North American prairies.     

Phylogenetic analysis of eleven species of Biomphalaria Preston, 1910 (Gastropoda: Planorbidae) based on comparisons of allozymes

Freshwater snails in the genus Biomphalaria transmit Schistosoma mansoni in Africa, South America and the Caribbean region. Although considerable attention has been given to the identification of species, little is known of evolutionary relationships among the species. A phylogenetic analysis of 25 populations representing 11 species was performed on 25 enzyme loci examined using starch gel electrophoresis. A phylogenetic analysis of the individual populations produced 60 trees of equal length. The 60 trees have a consistency index value of 75.9% and a retention index value of 76.5%. The phylogenetic analysis provided strong support for the monophyly of Biomphalaria with either 14 or 15 synapomorphies uniting all of the species included and separating them from the outgroup, two species of Helisoma. Four nominal species represented by multiple populations formed monophyletic groups. Populations of B. sudanica, B. choanomphala, and B. alexandrina were interspersed. Ten arrangements were obtained for the populations of these three species. A variety of ingroup taxa were used to root the trees, and all provided support for the use of Helisoma species as an outgroup. In all of the trees obtained, the African species together formed a monophyletic group. In none of the trees obtained did the neotropical species form a monophyletic group. A constrained analysis requiring the monophyly of the neotropical species as well as the African species resulted in 90 trees just two steps longer than the shortest trees. Analysis of the species from either hemisphere alone resulted in decreased resolution, as measured by an increase in the number of trees obtained. This finding suggests that further comparisons of species from the two hemispheres will be of considerable value. Finally, two species which are resistant to infection with S. mansoni were included among the eleven studied. Neither of these species formed the sister group to all of the other species included, indicating that susceptibility is the plesiomorphic state, and that resistance is derived. Similarly, in none of the trees obtained did the two resistant species fall out as sister taxa, indicating that resistance arose independently twice.     

Breeding strategies of Antarctic Petrels Thalassoica antarctica and Southern Fulmars Fulmarus glacialoides in the high Antarctic and implications for reproductive success

Breeding strategies of two closely related fulmarine petrels were studied on Ardery Island, on the continental coast of East Antarctica, where short summers are expected to narrow the time-window for reproduction. Both species had a similar breeding period (97 days from laying to fledging) but Antarctic Petrels Thalassoica antarctica bred up to 16 days earlier than Southern Fulmars. During the pre-laying exodus, all Antarctic Petrels deserted the colony, whereas some Southern Fulmars Fulmarus glacialoides remained. Antarctic Petrels exhibited stronger synchronization in breeding, made longer foraging trips and spent less time guarding their chicks than Southern Fulmars. Overall breeding success of both species was similar but failures of Antarctic Petrels were concentrated in the early egg-phase and after hatching, when parents ceased guarding. Southern Fulmars lost eggs and chicks later in the breeding cycle and so wasted more parental investment in failed breeding attempts. Different breeding strategies may be imposed by flight characteristics; Southern Fulmars are less capable of crossing large expanses of pack ice and need to delay breeding until the sea ice retreats and breaks up. However, due to the short summer they risk chick failure when weather conditions deteriorate late in the season.     

AN EARLY HERBIVOROUS LIZARD FROM THE LOWER CRETACEOUS OF JAPAN

Abstract:  The Lower Cretaceous Tetori Group of Japan has yielded diverse freshwater and terrestrial vertebrate assemblages. The most productive small vertebrate locality is the 'Kaseki-Kabe' or 'fossil-bluff' at Kuwajima, Hakusan City, Ishikawa Prefecture. These deposits have produced at least six distinct lizard taxa of which one, described and named here as Kuwajimalla kagaensis , has lanceolate denticulate teeth convergent on those of the living Iguana . This type of dentition is rare among living lizards and is usually considered indicative of herbivory and, more specifically, folivory. Kuwajimalla kagaensis provides the earliest unambiguous record of squamate herbivory. Comparisons with modern and fossil lizards suggest that Kuwajimalla may be an early relative of the macrocephalosaurines, a group of large herbivores well represented in the Upper Cretaceous of Mongolia.     

COMPARING TRANS-FAT AND TRANS-FAT-FREE DOUGHNUT SHORTENINGS BASED ON SENSORY EVALUATION AND OIL DEGRADATION

This is an initiative study on the use of trans -fat-free products in the bakery industry. A standardized doughnut product was cooked in three doughnut shortenings, one containing trans fat and two that were trans fat-free. Six hundred forty-one panelists, students, faculty and staff of a large northeastern university rated each of the three doughnuts on a variety of categories, including texture, moisture content and overall liking. Results showed that there were no significant differences between doughnuts cooked in the three shortenings – this was true for all attributes tested.
The results from this study have many significant implications for the foodservice industry, as they work to cut down or eliminate the use of trans fats in their establishments because of the significant health risks they have been proven to cause.

PRACTICAL APPLICATIONS

This study demonstrates the variances on texture, taste, appearance and overall liking characteristics of doughnuts fried in different doughnut shortenings. The nutritional breakdown of the doughnuts and the shortenings are also addressed. In the case of shortenings, the ideal type of fat is a mixture of canola, soybean and hydrogenated cottonseed. This shortening mixture, which is trans fat-free, produced the most preferred doughnut.     

Sources of plant-derived carbon and stability of organic matter in soil: implications for global change

Alterations in forest productivity and changes in the relative proportion of above‐ and belowground biomass may have nonlinear effects on soil organic matter (SOM) storage. To study the influence of plant litter inputs on SOM accumulation, the Detritus Input Removal and Transfer (DIRT) Experiment continuously alters above‐ and belowground plant inputs to soil by a combination of trenching, screening, and litter addition. Here, we used biogeochemical indicators [i.e., cupric oxide extractable lignin‐derived phenols and suberin/cutin‐derived substituted fatty acids (SFA)] to identify the dominant sources of plant biopolymers in SOM and various measures [i.e., soil density fractionation, laboratory incubation, and radiocarbon‐based mean residence time (MRT)] to assess the stability of SOM in two contrasting forests within the DIRT Experiment: an aggrading deciduous forest and an old‐growth coniferous forest. In the deciduous forest, removal of both above‐ and belowground inputs increased the total amount of SFA over threefold compared with the control, and shifted the SFA signature towards a root‐dominated source. Concurrently, light fraction MRT increased by 101 years and C mineralization during incubation decreased compared with the control. Together, these data suggest that root‐derived aliphatic compounds are a source of SOM with greater relative stability than leaf inputs at this site. In the coniferous forest, roots were an important source of soil lignin‐derived phenols but needle‐derived, rather than root‐derived, aliphatic compounds were preferentially preserved in soil. Fresh wood additions elevated the amount of soil C recovered as light fraction material but also elevated mineralization during incubation compared with other DIRT treatments, suggesting that not all of the added soil C is directly stabilized. Aboveground needle litter additions, which are more N‐rich than wood debris, resulted in accelerated mineralization of previously stored soil carbon. In summary, our work demonstrates that the dominant plant sources of SOM differed substantially between forest types. Furthermore, inputs to and losses from soil C pools likely will not be altered uniformly by changes in litter input rates.     

The trouble with flippers: a report on the prevalence of digital anomalies in Cetacea

The forelimbs of cetaceans (whales, dolphins, and porpoises) are unique among mammals as the digits exhibit hyperphalangy, and the entire limb is encased in a soft tissue flipper that functions to generate lift. The typical morphology of cetacean digits has been well documented by detailed anatomical studies. This study however furthers our understanding of cetacean forelimb anatomy by conducting a taxonomically broad survey of cetacean digital anomalies. Forelimb radiographs from museum collections provided the basis upon which we calculated the prevalence and documented the morphology of cetacean digital abnormalities. Results indicated that 11% (n = 255) of toothed whales displayed some type of aberrant ossification: the majority of these cases displayed a fusion of elements within a single digital ray, whereas cases exhibiting branched digits were rare. A small sample of baleen whale radiographs (n = 6) contained the only documented case of baleen whale polydactyly in a specimen of the gray whale (Eschrichtius). Furthermore, some Balaenoptera specimens displayed ossified elements within the interdigital spaces that lacked attachment to the adjacent digits and carpus. In addition, we speculated on the role that several genes may have played in creating cetacean digital anomalies. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 722–735.     

Faster returns on ‘leaf economics’ and different biogeochemical niche in invasive compared with native plant species

Plant‐invasive success is one of the most important current global changes in the biosphere. To understand which factors explain such success, we compared the foliar traits of 41 native and 47 alien‐invasive plant species in Oahu Island (Hawaii), a location with a highly endemic flora that has evolved in isolation and is currently vulnerable to invasions by exotic plant species. Foliar traits, which in most cases presented significant phylogenetic signal, i.e. closely related species tended to resemble each other due to shared ancestry, separated invasive from native species. Invasive species had lower leaf mass per area and enhanced capacities in terms of productivity (photosynthetic capacity) and nutrient capture both of macro‐ (N, P, K) and microelements (Fe, Ni, Cu and Zn). All these differences remain highly significant after removing the effects of phylogenetic history. Alien‐invasive species did not show higher efficiency at using limiting nutrient resources, but they got faster leaf economics returns and occupied a different biogeochemical niche, which helps to explain the success of invasive plants and suggests that potential increases in soil nutrient availability might favor further invasive plant success.