EVOLUTION OF ATLANTIC AND PACIFIC COD: LOSS OF GENETIC VARIATION AND GENE EXPRESSION IN PACIFIC COD

An allozyme investigation of 41 protein-coding loci in two morphologically similar fishes, Atlantic and Pacific cod, indicates that Pacific cod experienced a severe population bottleneck that led to the loss of gene diversity and gene expression. Pacific cod possesses a significantly lesser amount of gene diversity (H = 0.032) than Atlantic cod (H = 0.125) and lacks gene expression for Me-3. Allele-frequency distributions differ between species as predicted by neutral theory: Atlantic cod has a U-shaped distribution, which is expected for populations in drift-mutation equilibrium, whereas Pacific cod has a J-shaped distribution with an excess of low-frequency alleles. This excess may be explained by the appearance of new alleles through mutation which have not yet reached intermediate frequencies through drift. The population bottleneck in Pacific cod was most likely associated with founder populations that dispersed into the Pacific Ocean after the Bering Strait opened. Under the molecular-clock hypothesis a Nei genetic distance of 0.415 (based on 41 loci) suggests that Pacific cod dispersed into the Pacific Ocean soon after the Bering Strait opened in the mid-Pliocene, 3.0 to 3.5 million years ago.     

Volume of Distribution of Tritiated Water as a Measure of Total Body Water in Suckling Pigs

The total body water (TBW) was determined, using a method with tritiated water. One litter of 11 piglets was used for the experiment comprising repeated deterimnations during the first 6 weeks of life. The mean TBW defined as the 1½ hours distribution volume of tritium after intraperitoneal injection was found to decrease gradually from 80.1 % of the body-weight at 1 day of age to 72.7 % at 19 days of age and then remained fairly constant. A simple distillation technique for recovering the water from plasma was used. Small variations between pigs of the same age were found. The variations in individual pigs from time to time and the results of duplicate determinations seem reasonable.     

Zur Genetik und Systematik der Amoena-Gruppe der Gattung Godetia

Ohne ZusammenfassungMit 28 Textfiguren     

Eiweißreiche Wurzelknollen bei niedrigen Feuerbohnen

Zusammenfassung An niedrigen Feuerbohnen wurden cinfache oder verzweigte, knollenförmige Verdickungen der Wurzeln von bis zu 6 cm Dicke angetroffen. Der Höchstbetrag an Knollen je Pflanze betrug 325 g. Eine chemische Analyse ergab 4,2% Rohprotein und 31,3% Trockensubstanz. Der Geschmack erinnert an den der Kartoffeln.     

Strong positive effects of termites on savanna bird abundance and diversity are amplified by large herbivore exclusion

Vast areas of the African savanna landscapes are characterized by tree‐covered Macrotermes termite mounds embedded within a relatively open savanna matrix. In concert with termites, large herbivores are important determinants of savanna woody vegetation cover. The relative cover of woody species has considerable effects on savanna function. Despite the potentially important ecological relationships between termite mounds, woody plants, large herbivores, and birds, these associations have previously received surprisingly little attention. We experimentally studied the effects of termites and large herbivores on the avian community in Lake Mburo National Park, Uganda, where woody vegetation is essentially limited to termite mounds. Our experiment comprised of four treatments in nine replicates; unfenced termite mounds, fenced mounds (excluding large mammals), unfenced adjacent savanna, and fenced savanna. We recorded species identity, abundance, and behavior of all birds observed on these plots over a two‐month period, from late dry until wet season. Birds used termite mounds almost exclusively, with only 3.5% of observations occurring in the treeless intermound savanna matrix. Mean abundance and species richness of birds doubled on fenced (large herbivores excluded) compared to unfenced mounds. Feeding behavior increased when large mammals were excluded from mounds, both in absolute number of observed individuals, and relative to other behaviors. This study documents the fundamental positive impact of Macrotermes termites on bird abundance and diversity in an African savanna. Birds play crucial functional roles in savanna ecosystems, for example, by dispersing fruits or regulating herbivorous insect populations. Thus, the role of birds in savanna dynamics depends on the distribution and abundance of termite mounds.     

Analysing the large decline in coronary heart disease mortality in the Icelandic population aged 25-74 between the years 1981 and 2006

Background

Coronary heart disease (CHD) mortality rates have been decreasing in Iceland since the 1980s. We examined how much of the decrease between 1981 and 2006 could be attributed to medical and surgical treatments and how much to changes in cardiovascular risk factors.

Methodology

The previously validated IMPACT CHD mortality model was applied to the Icelandic population. The data sources were official statistics, national quality registers, published trials and meta-analyses, clinical audits and a series of national population surveys.

Principal Findings

Between 1981 and 2006, CHD mortality rates in Iceland decreased by 80% in men and women aged 25 to 74 years, which resulted in 295 fewer deaths in 2006 than if the 1981 rates had persisted. Incidence of myocardial infarction (MI) decreased by 66% and resulted in some 500 fewer incident MI cases per year, which is a major determinant of possible deaths from MI. Based on the IMPACT model approximately 73% (lower and upper bound estimates: 54%–93%) of the mortality decrease was attributable to risk factor reductions: cholesterol 32%; smoking 22%; systolic blood pressure 22%, and physical inactivity 5% with adverse trends for diabetes (−5%), and obesity (−4%). Approximately 25% (lower and upper bound estimates: 8%–40%) of the mortality decrease was attributable to treatments in individuals: secondary prevention 8%; heart failure treatments 6%; acute coronary syndrome treatments 5%; revascularisation 3%; hypertension treatments 2%, and statins 0.5%.

Conclusions

Almost three quarters of the large CHD mortality decrease in Iceland between 1981 and 2006 was attributable to reductions in major cardiovascular risk factors in the population. These findings emphasize the value of a comprehensive prevention strategy that promotes tobacco control and a healthier diet to reduce incidence of MI and highlights the potential importance of effective, evidence based medical treatments.