Material and structural properties of fin whale (Balaenoptera physalus) Zwischensubstanz

The oral anatomy of the fin whale (Balaenoptera physalus) consists of several major structures crucial to its engulfment method of feeding, such as stiff keratinized baleen plates, a large flaccid tongue, and a prominent vomer. One under‐documented part of this anatomy is the cream white Zwischensubstanz that holds the baleen plates to the rostrum at their dorsal base. The mechanical and structural properties of Zwischensubstanz play a key role in baleen plate dynamics and, on the grand scale, contribute to baleen whales' filtration efficiency and attainment of large body size. Compression and tensile tests on the Zwischensubstanz sampled from an 18 m fin whale showed that this material unexpectedly exhibits linear isotropic behaviour with Elastic Modulus of 2.56 ± 0.60 MPa and hysteresis of 0.44 ± 0.02 in compression despite apparent unidirectional growth. Acting similar to a soft rubber, the Zwischensubstanz absorbs and dissipates the enormous forces acting on baleen plates during engulfment feeding while maintaining spacing between the plates to maximize filtration efficiency. Microscopic analysis provided images of connective tissue papillae penetrating the base of the Zwischensubstanz and developing within it to emerge as fully formed, keratinized baleen plates. The plates develop from the papillae and a connective tissue sheet within the 5–7 cm deep Zwischensubstanz. The Zwischensubstanz provides a keratin matrix of concentrically oriented fibers around each papilla forming the hard baleen plates and frayed fringes used for filter feeding. During this formation, the Zwischensubstanz remains unchanged and appears to slough away to allow the baleen plate to grow unhindered. J. Morphol. 274:947–955, 2013. © 2013 Wiley Periodicals, Inc.     

Early release of eggs and embryos in a brooding ancient asexual ostracod: brood selection or a gambling strategy to increase fecundity?

Asexual lineages lack the means to purge their genomes of (deleterious) mutations through recombination. Evolutionary theory thus predicts that such lineages will be prone to early extinction. In brooding animals, brood selection might provide a mechanism to counter the accumulation of mutations. Of the three putative ancient asexual animal groups, only the darwinulid ostracods are brooders. Here, we test the incidence of egg and juvenile abortion in a darwinulid species, Penthesilenula brasiliensis, under two temperature treatments. Part of the offspring is released without brooding (close to 30% in one treatment). The majority of these aborted eggs hatches and develops. As it is unlikely that females are such bad judges of offspring quality, either the surviving animals will present deficiencies later on in development (brood selection) or early egg release can be a (bet-hedging) strategy to increase fecundity in favourable conditions.     

Tellurite reduction by Escherichia coli NDH-II dehydrogenase results in superoxide production in membranes of toxicant-exposed cells

Tellurite, the most soluble tellurium oxyanion, is extremely harmful for most microorganisms. Part of this toxicity is due to the generation of reactive oxygen species that in turn cause oxidative stress. However, the way in which tellurite interferes with cellular processes is not well understood to date. Looking for new cellular tellurite targets, we decided to evaluate the functioning of the electron transport chain in tellurite-exposed cells. In this communication we show that the E. coli ndh gene, encoding NDH-II dehydrogenase, is significantly induced in toxicant-exposed cells and that the enzyme displays tellurite-reducing activity that results in increased superoxide levels in vitro.     

Optimization for non-linear inverse problems

Abstract  The non-linear inversion of geophysical data in general does not yield a unique solution, but a single model representing the investigated field, and is preferred for an easy geological interpretation of observations. The analyzed region is constituted by a number of sub-regions where multi-valued non-linear inversion is applied, which leads to a multi-valued solution. Therefore, combining the values of the solution in each sub-region, many acceptable models are obtained for the entire region and this complicates the geological interpretation of geophysical investigations. In this paper new methodologies are presented, capable of selecting one model among all acceptable ones, that satisfies different criteria of smoothness in the explored space of solutions. In this work we focus on the non-linear inversion of surface wave dispersion curves, which gives structural models of shear-wave velocity versus depth. Keywords Discrete vector optimization, Non-linear inversion, Alps lithosphere Subject codes: G13007, G18009, G17040, P19005 Mathematics Subject Classification 2000: 49L20, 65K10     

Back to basics in COVID-19: Antigens and antibodies—Completing the puzzle

The outbreak of the coronavirus disease 2019 (COVID-19) has gathered 1 year of scientific/clinical information. This informational asset should be thoroughly and wisely used in the coming year colliding in a global task force to control this infection. Epidemiology of this infection shows that the available estimates of SARS-CoV-2 infection prevalence largely depended on the availability of molecular testing and the extent of tested population. Within molecular diagnosis, the viability and infectiousness of the virus in the tested samples should be further investigated. Moreover, SARS-CoV-2 has a genetic normal evolution that is a dynamic process. The immune system participates to the counterattack of the viral infection by pathogen elimination, cellular homoeostasis, tissue repair and generation of memory cells that would be reactivated upon a second encounter with the same virus. In all these stages, we still have knowledge to be gathered regarding antibody persistence, protective effects and immunological memory. Moreover, information regarding the intense pro-inflammatory action in severe cases still lacks and this is important in stratifying patients for difficult to treat cases. Without being exhaustive, the review will cover these important issues to be acknowledged to further advance in the battle against the current pandemia.     

Influence of fruit on habitat selection of Asian bears in a tropical forest

Wild bear populations in Southeast Asia are threatened with extinction, but the ecology and distribution of the 2 species occurring in the region's protected areas is poorly known, so there is little scientific basis underlying conservation strategies. We used bear signs, primarily claw marks on climbed trees, to study habitat selection and distribution of Asiatic black bear (Ursus thibetanus) and sun bear (Helarctos malayanus) across Khao Yai National Park, Thailand from March to December 2008. We found black bear claw marks in 24 of 30 random sample blocks (80%), indicating that this species was widely distributed across Khao Yai. Sun bear signs were much scarcer: their claw marks occurred in 11 blocks (37%); data were too sparse for sun bear so we limited our focus to Asiatic black bear. Using logistic regression, we found that fruit abundance best explained variation in presence of black bear, whereas human disturbance, distance to park edge, elevation, and ground cover had little influence. Fruits appear to be a key resource for Asiatic black bears, and factors affecting fruit abundance or shifts in seasonality (e.g., climate change) will impact bear populations. Knowledge of this relationship will allow managers to be more proactive in managing bears. We recommend using sign surveys for monitoring changes in black bear occupancy as they are inexpensive, efficient, and can be conducted by trained park rangers. © 2011 The Wildlife Society.     

Impact of micro and macroporous TFF membranes on product sieving and chromatography loading for perfusion cell culture

Bioprocess intensification can be achieved through high cell density perfusion cell culture with continuous protein capture integration. Protein passage and cell retention are commonly accomplished using tangential flow filtration systems consisting of microporous membranes. Significant challenges, including low efficiency and decaying product sieving over time, are commonly observed in these cell retention devices. Here, we demonstrate that a macroporous membrane overcomes the product sieving challenges when comparing to several other membrane chemistries and pore sizes within the microporous range. This way, variable chromatography column loading is avoided. The macroporous membrane yielded a 13,000 L/m² volumetric throughput. The membrane's cut-off size results in an increased permeate turbidity due to particles passage, such as cell debris, through pores ranging from 1 to 4 µm. In addition, successful chromatography column plugging mitigation was achieved by employing depth filtration before the chromatographic step. Depth filtration volumetric throughputs were between 600 and 1,000 L/m². Combing a macroporous cell retention device with a depth filter not only provided an alternative to address the challenge of undesired long protein residence times in the bioreactor due to product sieving decay, but also exhibited a throughput increase, making the integration of multicolumn capture chromatography with a perfusion cell culture a more robust process.     

Lack of trnL intron in the thermoacidophilic red alga Galdieria sulphuraria (Galdieri) Merola

Abstract

The plastid trnC‐trnL(UAA)‐ilvH region from Galdieria sulphuraria was cloned and sequenced with the aim of verifying the absence of the trnL intron. The sequence alignment shows both the absence of a trnL intron and the colinearity of the whole region of the plastidial DNA of G. sulphuraria with that of the other thermoacidophilic red algae.