Importance of the lactate anion in control of breathing

Hardarson, Thorir, Jon O. Skarphedinsson, and TorarinnSveinsson. Importance of the lactate anion in control ofbreathing. J. Appl. Physiol. 84(2):411-416, 1998.The purpose of this study was to examine theeffects of raising the arterialLa andK⁺ levels on minute ventilation(E) in rats. EitherLa or KCl solutions wereinfused in anesthetized spontaneously breathing Wistar rats to raisethe respective ion arterial concentration ([La] and[K⁺]) gradually tolevels similar to those observed during strenuous exercise.E, blood pressure, and heart rate wererecorded continuously, and arterial[La],[K⁺], pH, and bloodgases were repeatedly measured from blood samples. To prevent changesin pH during the Lainfusions, a solution of sodium lactate and lactic acid was used. Raising [La] to13.2 ± 0.6 (SE) mM induced a 47.0 ± 4.0% increase inE without any concomitant changes ineither pH or PCO₂. Raising[K⁺] to 7.8 ± 0.11 mM resulted in a 20.3 ± 5.28% increase inE without changes in pH. Thus ourresults show that Laitself, apart from lactic acidosis, may be important in increasing E during strenuous exercise, and weconfirm earlier results regarding the role of arterial[K⁺] in the control ofE during exercise.

     

Adaptive Introgression Facilitates Adaptation to High Latitudes in European Aspen (Populus tremula L.)

Understanding local adaptation has become a key research area given the ongoing climate challenge and the concomitant requirement to conserve genetic resources. Perennial plants, such as forest trees, are good models to study local adaptation given their wide geographic distribution, largely outcrossing mating systems, and demographic histories. We evaluated signatures of local adaptation in European aspen (Populus tremula) across Europe by means of whole-genome resequencing of a collection of 411 individual trees. We dissected admixture patterns between aspen lineages and observed a strong genomic mosaicism in Scandinavian trees, evidencing different colonization trajectories into the peninsula from Russia, Central and Western Europe. As a consequence of the secondary contacts between populations after the last glacial maximum, we detected an adaptive introgression event in a genome region of ∼500 kb in chromosome 10, harboring a large-effect locus that has previously been shown to contribute to adaptation to the short growing seasons characteristic of Northern Scandinavia. Demographic simulations and ancestry inference suggest an Eastern origin—probably Russian—of the adaptive Nordic allele which nowadays is present in a homozygous state at the north of Scandinavia. The strength of introgression and positive selection signatures in this region is a unique feature in the genome. Furthermore, we detected signals of balancing selection, shared across regional populations, that highlight the importance of standing variation as a primary source of alleles that facilitate local adaptation. Our results, therefore, emphasize the importance of migration–selection balance underlying the genetic architecture of key adaptive quantitative traits.     

Mature males of Arctic charr,Salvelinus alpinus,release F-type prostaglandins to attract conspecific mature females and stimulate their spawning behaviour

Synopsis We examined the behavioural and biological functions of prostaglandins (PG) of F-type as a chemosensory signal during spawning in Arctic charr. Immunoassay revealed F-type PGs in water inhabited by ripe charr of both sexes performing spawning-related acts. High concentrations of immunoreactive PGFs seemed to coincide with male spawning activity. Ripe isolated males were more odorous to other charr (as assayed by EOG) than either females or immature charr. When these males received chemical cues from ovulated females, they increased their release of odorants, including F-type PGs, into the water. PGF_2α at concentrations of 0.1 nM attracted ovulated females and ripe males. It also stimulated digging behaviour in mature females. It is concluded that F-type PGs or their derivatives are released by ripe males on the spawning grounds to attract females and elicit their spawning behaviour.     

Ultra-barcoding in cacao (Theobroma spp.; Malvaceae) using whole chloroplast genomes and nuclear ribosomal DNA

? Premise of study: To reliably identify lineages below the species level such as subspecies or varieties, we propose an extension to DNA-barcoding using next-generation sequencing to produce whole organellar genomes and substantial nuclear ribosomal sequence. Because this method uses much longer versions of the traditional DNA-barcoding loci in the plastid and ribosomal DNA, we call our approach ultra-barcoding (UBC). ? Methods: We used high-throughput next-generation sequencing to scan the genome and generate reliable sequence of high copy number regions. Using this method, we examined whole plastid genomes as well as nearly 6000 bases of nuclear ribosomal DNA sequences for nine genotypes of Theobroma cacao and an individual of the related species T. grandiflorum, as well as an additional publicly available whole plastid genome of T. cacao. ? Key results: All individuals of T. cacao examined were uniquely distinguished, and evidence of reticulation and gene flow was observed. Sequence variation was observed in some of the canonical barcoding regions between species, but other regions of the chloroplast were more variable both within species and between species, as were ribosomal spacers. Furthermore, no single region provides the level of data available using the complete plastid genome and rDNA. ? Conclusions: Our data demonstrate that UBC is a viable, increasingly cost-effective approach for reliably distinguishing varieties and even individual genotypes of T. cacao. This approach shows great promise for applications where very closely related or interbreeding taxa must be distinguished.     

Effects on growth of Arctic charr of handling, anaesthesia and repeated formalin bathing shortly after first exogenous feeding

An experiment was conducted to test whether handling, anaesthesia or repeated formalin bathing had any effect on the growth rate in first feeding Arctic charr held in separate containers. The results show that these treatments had no effect on the growth rate.     

Is a Cancer Diagnosis Associated with Subsequent Risk of Transient Global Amnesia?

Background

Psychological stress has been associated with transient global amnesia (TGA). Whether a cancer diagnosis, a severely stressful life event, is associated with subsequent risk of TGA has not been studied.

Methods

Based on the Swedish Cancer Register and Patient Register, we conducted a prospective cohort study including 5,365,608 Swedes at age 30 and above during 2001–2009 to examine the relative risk of TGA among cancer patients, as compared to cancer-free individuals. Incidence rate ratios (IRRs) and their 95% confidence intervals (CIs) derived from Poisson regression were used as estimates of the association between cancer diagnosis and the risk of TGA.

Results

During the study 322,558 individuals (6.01%) received a first diagnosis of cancer. We identified 210 cases of TGA among the cancer patients (incidence rate, 0.22 per 1000 person-years) and 4,887 TGA cases among the cancer-free individuals (incidence rate, 0.12 per 1000 person-years). Overall, after adjustment for age, sex, calendar year, socioeconomic status, education and civil status, cancer patients had no increased risk of TGA than the cancer-free individuals (IRR, 0.99; 95% CI, 0.86–1.13). The IRRs did not differ over time since cancer diagnosis or across individual cancer types. The null association was neither modified by sex, calendar period or age.

Conclusion

Our study did not provide support for the hypothesis that patients with a new diagnosis of cancer display a higher risk of TGA than cancer-free individuals.     

Chemical control of Penthaleus major (Acari: Prostigmata) in hayfields in Iceland

The plant parasitic mite Penthaleus major (Dugès) occurs as a pest on perennial grasses in hayfields in Iceland, northern Norway, and southern Greenland. In these areas it appears as a summer phenomenon, contrary to more southern locations, where it appears as a pest on winter crops. Up to 500 individuals of P. major were collected per day in pitfall traps. Spring application of 44 ml/ha of permethrin and 5 ml of deltamethrin significantly reduced but did not eliminate the populations of P. major the following weeks. In addition to this immediate effect, spring application also decreased the mite populations in the fall and even the following spring. Additional effects might be obtained by earlier spring application. Despite a significant reduction in mite populations and reduction in visible plant damage, significant differences on dry matter yield were rarely registered. A side effect of application was a small but significant reduction in potassium-content of the yield, and the reduction in mite population was accompanied by a corresponding reduction in the number of spiders.     

Complex origin of Trinitario-type Theobroma cacao (Malvaceae) from Trinidad and Tobago revealed using plastid genomics

Trinidad and Tobago has a long history of producing high-quality cacao (Theobroma cacao L.). Cacao genotypes in Trinidad and Tobago are of a highly distinctive kind, the so-called “Trinitario” cultivar group, widely considered to be of elite quality. The origin of Trinitario cacao is unclear, although it is generally considered to be of hybrid origin. We used massive parallel sequencing to identify polymorphic plastidic single nucleotide polymorphisms (cpSNPs) and polymorphic plastidic simple sequence repeats (cpSSRs) in order to determine the origin of the Trinitario cultivar group by comparing patterns of polymorphism to a reference set of ten completely sequenced chloroplast genomes (nine T. cacao and one outgroup, T. grandiflorum (Willd. ex Spreng.) Schum). Only three cpSNP haplotypes were present in the Trinitario cultivars sampled, each highly distinctive and corresponding to reference genotypes for the Criollo (CRI), Upper Amazon Forastero (UAF) and Lower Amazon Forastero (LAF) varietal groups. These three cpSNP haplotypes likely represent the founding lineages of cacao to Trinidad and Tobago. The cpSSRs were more variable with eight haplotypes, but these clustered into three groups corresponding to the three cpSNP haplotypes. The most common haplotype found in farms of Trinidad and Tobago was LAF, followed by UAF and then CRI. We conclude that the Trinitario cultivar group is of complex hybrid origin and has derived from at least three original introduction events.