New encounters in Arctic waters: a comparison of metabolism and performance of polar cod (<Emphasis Type="Italic">Boreogadus saida</Emphasis>) and Atlantic cod (<Emphasis Type="Italic">Gadus morhua</Emphasis>) under ocean acidification and warming

Oceans are experiencing increasing acidification in parallel to a distinct warming trend in consequence of ongoing climate change. Rising seawater temperatures are mediating a northward shift in distribution of Atlantic cod (Gadus morhua), into the habitat of polar cod (Boreogadus saida), that is associated with retreating cold water masses. This study investigates the competitive strength of the co-occurring gadoids under ocean acidification and warming (OAW) scenarios. Therefore, we incubated specimens of both species in individual tanks for 4 months, under different control and projected temperatures (polar cod: 0, 3, 6, 8 °C, Atlantic cod: 3, 8, 12, 16 °C) and PCO₂ conditions (390 and 1170 µatm) and monitored growth, feed consumption and standard metabolic rate. Our results revealed distinct temperature effects on both species. While hypercapnia by itself had no effect, combined drivers caused nonsignificant trends. The feed conversion efficiency of normocapnic polar cod was highest at 0 °C, while optimum growth performance was attained at 6 °C; the long-term upper thermal tolerance limit was reached at 8 °C. OAW caused only slight impairments in growth performance. Under normocapnic conditions, Atlantic cod consumed progressively increasing amounts of feed than individuals under hypercapnia despite maintaining similar growth rates during warming. The low feed conversion efficiency at 3 °C may relate to the lower thermal limit of Atlantic cod. In conclusion, Atlantic cod displayed increased performance in the warming Arctic such that the competitive strength of polar cod is expected to decrease under future OAW conditions.     

New records of ectoparasitic Acari (Arachnida) and Streblidae (Diptera) from bats in Jalisco,Mexico

Ectoparasites of bats in the Neotropics are diverse and play numerous ecological roles as vectors of microbial pathogens and endoparasites and as food sources for other cave fauna living both on their hosts and in bat roosts. The ectoparasites of bats in Jalisco State of western Mexico have not been as well described as those of other states with recent checklists that have focused primarily on the Yucatan Peninsula. We captured bats from 2011–2015 on the south coast and Sierra de Amula, Jalisco using mist nets, and we removed ectoparasites by hand. We identified 24 species of streblid bat flies and six ectoparasitic mites from bats caught in mist nets. There were an additional eight possibly undescribed species of Streblidae. Our collections extend the known range of species into Jalisco.     

Temperate migrants and resident bird species in Afro‐tropical savannahs show similar levels of ecological generalism

The specificity of an animal's habitat requirements will determine its ability to deal with anthropogenic climate and habitat change. Migratory birds are thought to be particularly vulnerable to such change, but theory predicts that they should be largely generalists. This prediction was tested with the aim of assessing whether migratory Palaearctic‐breeding birds wintering in the savannah biome of Africa are more or less generalist in their habitat use compared with taxonomically and ecologically similar Afro‐tropical resident species. The degree of specialization of these species groups to certain habitat characteristics was assessed and compared by calculating the relative occurrence of the species along habitat gradients, where wide occurrence indicates generalism and narrow occurrence indicates specialism. Palaearctic migrants as a group could not clearly be distinguished as generalists relative to Afro‐tropical residents with respect to habitat attributes. The only indication of greater flexibility in Palaearctic migrants was a significant tendency to use habitats over a wider latitudinal range. The results suggest that migrants are generalists, but not necessarily more generalist than taxonomically similar resident species that also occur over a wide range of habitat types within the savannah biome. The availability of specific habitat requirements on the wintering grounds in Africa is therefore unlikely to be a primary limiting factor for many Afro‐Palaearctic migratory bird species.     

The influence of culture media on embryonic renal collecting duct cell differentiation

Summary During kidney development the embryonic ampullar collecting duct (CD) epithelium changes its function. The capability for nephron induction is lost and the epithelium develops into a heterogeneously composed epithelium consisting of principal and intercalated cells. Part of this development can be mimicked under in vitro conditions, when embryonic collecting duct epithelia are isolated from neonatal rabbit kidneys and kept under perfusion culture. The differentiation pattern is quite different when the embryonic collecting duct epithelia are cultured in standard Iscove’s modified Dulbecco’s medium as compared to medium supplemented with additional NaCl. Thus, the differentiation behavior of embryonic CD epithelia is unexpectedly sensitive. To obtain more information about how much influence the medium has on cell differentiation, we tested medium 199, basal medium Eagle, Williams’ medium E, McCoys 5A medium, and Dulbecco’s modified Eagle medium under serum-free conditions. The experiments show that in general, all of the tested media are suitable for culturing embryonic collecting duct epithelia. According to morphological criteria, there is no difference in morphological epithelial cell preservation. The immunohistochemical data reveal two groups of expressed antigens. Constitutively expressed antigens such as cytokeratin 19, P_CD 9, Na/K ATPase, and laminin are present in all cells of the epithelia independent of the culture media used. In contrast, a group of antigens detected by mab 703, mab 503, and PNA is found only in individual series. Thus, each culture medium produces epithelia with a very specific cell differentiation pattern.     

PIC-1/SUMO-1-Modified PML-Retinoic Acid Receptor α Mediates Arsenic Trioxide-Induced Apoptosis in Acute Promyelocytic Leukemia

Fusion proteins involving the retinoic acid receptor alpha (RARalpha) and PML or PLZF nuclear protein are the genetic markers of acute promyelocytic leukemia (APL). APLs with PML-RARalpha or PLZF-RARalpha fusion protein differ only in their response to retinoic acid (RA) treatment: the t(15;17) (PML-RARalpha-positive) APL blasts are sensitive to RA in vitro, and patients enter disease remission after RA treatment, while those with t(11;17) (PLZF-RARalpha-positive) APLs do not. Recently it has been shown that complete remission can be achieved upon treatment with arsenic trioxide (As2O3) in PML-RARalpha-positive APL, even when the patient has relapsed and the disease is RA resistant. This appears to be due to apoptosis induced by As2O3 in the APL blasts by poorly defined mechanisms. Here we report that (i) As2O3 induces apoptosis only in cells expressing the PML-RARalpha, not the PLZF-RARalpha, fusion protein; (ii) PML-RARalpha is partially modified by covalent linkage with a PIC-1/SUMO-1-like protein prior to As2O3 treatment, whereas PLZF-RARalpha is not; (iii) As2O3 treatment induces a change in the modification pattern of PML-RARalpha toward highly modified forms; (iv) redistribution of PML nuclear bodies (PML-NBs) upon As2O3 treatment is accompanied by recruitment of PIC-1/SUMO-1 into PML-NBs, probably due to hypermodification of both PML and PML-RARalpha; (v) As2O3-induced apoptosis is independent of the DNA binding activity located in the RARalpha portion of the PML-RARalpha fusion protein; and (vi) the apoptotic process is bcl-2 and caspase 3 independent and is blocked only partially by a global caspase inhibitor. Taken together, these data provide novel insights into the mechanisms involved in As2O3-induced apoptosis in APL and predict that treatment of t(11;17) (PLZF-RARalpha-positive) APLs with As2O3 will not be successful.     

Intraflock variation in the speed of escape-flight response on attack by an avian predator

The benefits of flocking to prey species, whether through collective vigilance,dilution of risk, or predator confusion, depend on flock members respondingin a coordinated way to attack. We videotaped sparrowhawks attackingredshank flocks to determine if there were differences in thetiming of escape flights between flock members and the factorsthat might affect any differences. Sparrowhawks are surpriseshort-chase predators, so variation in the time taken to takeflight on attack is likely to be a good index of predation risk.Most birds in a flock flew within 0.25 s of the first bird flying,and all birds were flying within 0.7 s. Redshanks that werevigilant, that were closest to the approaching raptor, and thatwere close to their neighbors took flight earliest within aflock. Birds in larger flocks took longer, on average, to takeflight, measured from the time that the first bird in the flockflew. Most birds took flight immediately after near neighbors tookoff, but later flying birds were more likely to fly immediatelyafter more distant neighbors took flight. This result, alongwith the result that increased nearest neighbor distance increasedflight delay, suggests that most redshanks flew in responseto conspecifics flying. The results strongly suggest that thereis significant individual variation in predation risk withinflocks so that individuals within a flock will vary in benefitsthat they gain from flocking.     

Structural and Functional Analysis of a Novel Coiled-Coil Protein Involved in Ypt6 GTPase-regulated Protein Transport in Yeast

The yeast transport GTPase Ypt6p is dispensable for cell growth and secretion, but its lack results in temperature sensitivity and missorting of vacuolar carboxypeptidase Y. We previously identified four yeast genes (SYS1, 2, 3, and 5) that on high expression suppressed these phenotypic alterations. SYS3 encodes a 105-kDa protein with a predicted high α-helical content. It is related to a variety of mammalian Golgi-associated proteins and to the yeast Uso1p, an essential protein involved in docking of endoplasmic reticulum–derived vesicles to the cis-Golgi. Like Uso1p, Sys3p is predominatly cytosolic. According to gel chromatographic, two-hybrid, and chemical cross-linking analyses, Sys3p forms dimers and larger protein complexes. Its loss of function results in partial missorting of carboxypeptidase Y. Double disruptions of SYS3 and YPT6 lead to a significant growth inhibition of the mutant cells, to a massive accumulation of 40- to 50-nm vesicles, to an aggravation of vacuolar protein missorting, and to a defect in α-pheromone processing apparently attributable to a perturbation of protease Kex2p cycling between the Golgi and a post-Golgi compartment. The results of this study suggest that Sys3p, like Ypt6p, acts in vesicular transport (presumably at a vesicle-docking stage) between an endosomal compartment and the most distal Golgi compartment.