Metabolism of trimethylamines in kelp bass (Paralabrax clathratus) and marine and freshwater pink salmon (Oncorhynchus gorbuscha)

Summary ³H or¹⁴C labeled tracers were used to investigate the metabolism of trimethylamine (TMA), trimethylamine oxide (TMAO), choline, and betaine in free swimming kelp bass (Paralabrax clathratus). An indwelling cannula in the ventral aorta was used to administer tracer and withdraw blood samples. The concentrations of TMA and TMAO were determined in liver, muscle, and plasma. The TMA liver content is higher than that of muscle (0.85 vs 0.01 moles/g wet tissue) while the amount of TMAO in muscle greatly exceeds its liver concentration (60 vs 0.04 moles/g wet tissue). Prolonged fasting (21 and 75 days) or feeding the fish a squid diet containing high levels of TMAO did not alter the tissue concentrations of TMA or TMAO, suggesting that these compounds are endogenous in origin and that their tissue concentrations are subject to regulation. Comparison of the radiospecific activities of TMA and TMAO, and the administered TMA tracer suggest that TMA is channled directly to TMAO in the liver without equilibration in the hepatic TMA pool. The conversion kinetics of TMA to TMAO and the distribution of these amines in liver and muscle with time suggest that labeled TMA is rapidly taken up into a sequestered pool from which it is slowly released, oxidized to TMAO in the liver, and then transported via the circulation to the muscle mass. The location of this proposed sequestered TMA pool was not determined. Experiments with labeled choline and betaine suggest that these compounds are interconverted in the liver and that enzymes are present for conversion of choline betaine TMA TMAO. Labeled dimethylamine (DMA) was not metabolized and is, therefore, probably not a precursor of TMA and TMAO. [¹⁴C]Trimethylamine (TMA) was also used to investigate the possible role of trimethylamine oxide (TMAO) as an osmoregulatory compound in migrating prespawning cannulated Pacific pink salmon (Oncorhynchus gorbuscha) taken from marine or fresh water environments. Marine and fresh water salmon oxidized administered [¹⁴C]TMA to TMAO; labeled metabolites other than TMA and TMAO were not detected. Four hours after [¹⁴C]TMA injection about 10% of the administered dose was present in muscle as labeled TMAO and about 33% as TMA. Unlike our finding in kelp bass, [¹⁴C]TMAO was not recovered in liver, although low amounts of labeled TMA were found (0.4% of administered dose). Labeled TMA and TMAO, however, were detected in liver after [¹⁴C]betaine adminstration to a marine salmon, indicating that TMA-mono-oxygenase is present in salmon liver. The presence of labeled choline indicates that choline and betaine are interconverted as in kelp bass. The amount of [¹⁴C]TMA oxidized to [¹⁴C]TMAO and then accumulated in the muscle mass is the same in marine and fresh water salmon, as is the amount of chemical TMAO present (4.6 moles/g muscle).     

New views of humpback whale flow dynamics and oral morphology during prey engulfment

The rise of inexpensive, user‐friendly cameras and editing software promises to revolutionize data collection with minimal disturbance to marine mammals. Video sequences recorded by aerial drones and GoPro cameras provided close‐up views and unique perspectives of humpback whales engulfing juvenile salmon at or just below the water surface in Southeast Alaska and Prince William Sound. Although humpback feeding is famous for its flexibility, several stereotyped events were noted in the 47 lunges we analyzed. Engulfment was rapid (mean 2.07 s), and the entrance through which the tongue inverts into the ventral pouch was seen as water rushes in. Cranial elevation was a major contributor to gape, and pouch contraction sometimes began before full gape closure, with reverberating waves indicating rebounding flow of water within the expanded pouch. Expulsion of filtered water began with a small splash at the anterior of the mouth, followed by sustained excurrent flow in the mouth's central or posterior regions. Apart from a splash of rebounding water, water within the mouth was surprisingly turbulence‐free during engulfment, but submersion of the whale's head created visible surface whirlpools and vortices which may aggregate prey for subsequent engulfment.     

Spontaneous and assisted restoration of vegetation on the bottom of a former water reservoir,the Elwha River,Olympic National Park,WA, U.S.A.

Early seral vegetation was studied on a former lake bottom after the removal of the 64‐m‐tall Glines Canyon Dam on the Elwha River. In 2015, vegetation cover of all vascular plant species was determined in 63 plots located on sites that emerged in 2011–2012. The sites had been planted and/or seeded, or were permitted to revegetate spontaneously. The plots were further classified by substrate texture: coarse sediments on the valley bottom and fine ones on the valley slopes. Plots were located randomly along random transects perpendicular to the former lake shore that extended into coarse sediment terraces perched above the floodplain. Additionally, 32 plots were sampled in surrounding native forests near these transects. Data were analyzed by detrended correspondence analysis and by canonical correspondence analysis. Substrate texture, that is whether fine or coarse, appeared to explain most of the variability in vegetation. The distance to forest and successional age, that is time since the site had been drained, were also significant explanatory variables, while assisted restoration by planting and seeding appeared to be insignificant to date. Spontaneous succession on fine sediments led to a species composition approaching that of adjacent natural forests. Invasive species were much less abundant than expected. Spontaneous restoration of vegetation on fine sediments in drained lake bottoms can rapidly produce a desirable vegetation composition and structure. On coarse sediments, active restoration may be useful to accelerate the development of native vegetation communities.     

A single origin of large colony size in allodapine bees suggests a threshold event among 50 million years of evolutionary tinkering

Evolutionary origins of highly eusocial organization involving morphological castes have been very rare, yet these origins have often led to enormous diversification and ecological success. This suggests that once an apparently severe selective barrier to highly eusocial behaviour is overcome, major new adaptive landscapes open up. One would therefore expect a discontinuity in patterns of evolutionary change across this barrier. However, we do not know if highly eusocial organization has evolved incrementally from less complex societies, or if it has involved some kind of evolutionary leap. Our study examines this issue using colony size data from 33 allodapine bee species, with a crown age of ca. 47 Mya. Our species cover all major allodapine clades, and include Exoneurella tridentata, the only known allodapine with morphologically discrete castes. Phylogenetic analyses indicate a strong effect of phylogeny on the evolution of maximum brood size, but the effect of phylogeny on maximum colony size (number of adults) depends on whether E. tridentata is excluded or included in analyses. We found no evidence of punctuational change in maximum colony or brood sizes over the phylogeny as a whole, but colony and brood sizes in E. tridentata fall well beyond variation among the other allodapines. Colony size in E. tridentata therefore represents an evolutionary outcome that does not fit within the kinds of incremental changes found in other allodapines. We propose that E. tridentata indicates the crossing of an important threshold, and this has entailed some very unusual ecological circumstances.     

The relative importance of genetic and nongenetic inheritance in relation to trait plasticity in Callosobruchus maculatus

A trait's response to natural selection will reflect the nature of the inheritance mechanisms that mediate the transmission of variation across generations. The relative importance of genetic and nongenetic mechanisms of inheritance is predicted to be related to the degree of trait plasticity, with nongenetic inheritance playing a greater role in the cross‐generational transmission of more plastic traits. However, this prediction has never been tested. We investigated the influence of genetic effects and nongenetic parental effects in two morphological traits differing in degree of plasticity by manipulating larval diet quality within a cross‐generational split‐brood experiment using the seed beetle Callososbuchus maculatus. In line with predictions, we found that the more plastic trait (elytron length) is strongly influenced by both maternal and paternal effects whereas genetic variance is undetectable. In contrast, the less plastic trait (first abdominal sternite length) is not influenced by parental effects but exhibits abundant genetic variance. Our findings support the hypothesis that environment‐dependent parental effects may play a particularly important role in highly plastic traits and thereby affect the evolutionary response of such traits.     

Assessing freshwater use impacts in LCA: Part I—inventory modelling and characterisation factors for the main impact pathways

Background, aim and scope

Freshwater is a basic resource for humans; however, its link to human health is seldom related to lack of physical access to sufficient freshwater, but rather to poor distribution and access to safe water supplies. On the other hand, freshwater availability for aquatic ecosystems is often reduced due to competition with human uses, potentially leading to impacts on ecosystem quality. This paper summarises how this specific resource use can be dealt with in life cycle analysis (LCA).

Main features

The main quantifiable impact pathways linking freshwater use to the available supply are identified, leading to definition of the flows requiring quantification in the life cycle inventory (LCI).

Results

The LCI needs to distinguish between and quantify evaporative and non-evaporative uses of ‘blue’ and ‘green’ water, along with land use changes leading to changes in the availability of freshwater. Suitable indicators are suggested for the two main impact pathways [namely freshwater ecosystem impact (FEI) and freshwater depletion (FD)], and operational characterisation factors are provided for a range of countries and situations. For FEI, indicators relating current freshwater use to the available freshwater resources (with and without specific consideration of water ecosystem requirements) are suggested. For FD, the parameters required for evaluation of the commonly used abiotic depletion potentials are explored.

Discussion

An important value judgement when dealing with water use impacts is the omission or consideration of non-evaporative uses of water as impacting ecosystems. We suggest considering only evaporative uses as a default procedure, although more precautionary approaches (e.g. an ‘Egalitarian’ approach) may also include non-evaporative uses. Variation in seasonal river flows is not captured in the approach suggested for FEI, even though abstractions during droughts may have dramatic consequences for ecosystems; this has been considered beyond the scope of LCA.

Conclusions

The approach suggested here improves the representation of impacts associated with freshwater use in LCA. The information required by the approach is generally available to LCA practitioners

Recommendations and perspectives

The widespread use of the approach suggested here will require some development (and consensus) by LCI database developers. Linking the suggested midpoint indicators for FEI to a damage approach will require further analysis of the relationship between FEI indicators and ecosystem health.     

Assessing freshwater use impacts in LCA,part 2: case study of broccoli production in the UK and Spain

Background, aim and scope  

Milà i Canals et al. (Int J Life Cycle Ass 14(1):28-42, 2009) referred to as ‘Part 1’ in this paper) showed that impacts associated with use of freshwater must be treated more rigorously than is usual in life cycle assessment (LCA), going beyond the conventional consideration only of ‘blue’ water (i.e. irrigation and other abstractions), and suggested an operational method to include the impacts on freshwater ecosystems (freshwater ecosystem impact) and abiotic resource depletion (freshwater depletion). The inclusion of water-related impacts in LCA is of paramount importance, particularly for agricultural systems due to their large water consumption worldwide. A case study of UK consumption of broccoli grown in the UK and Spain is presented here to illustrate the method suggested in Part 1.     

Assessment of estrus detection by visual observation and electronic detection methods and characterization of factors associated with estrus and pregnancy in beef heifers

One hundred and sixty-four beef heifers representing Angus, Brahman and their crosses were subjected to estrus synchronization treatment following evaluation of weight, body condition score and reproductive tract. Heifers were assigned to 1 of 2 methods of estrus detection, either visual observation for signs of standing estrus or a rump-mounted pressure-sensitive detection device. All heifers were artificially inseminated during a 25d insemination period and then bred by a bull. The effectiveness of estrus detection and timely insemination were evaluated by the type of detection method, breed and breeding event resulting in a pregnancy. Although there was not a significant difference in first service conception for method of detection, at the end of a 25-d insemination period, 60.5% of the visually observed heifers were pregnant, while only 45.8% of the heifers detected by the mount detection device were pregnant (P = 0.05). The reduced 25-d conception rate in the pressure-sensitive detection group suggested that insemination of detected heifers may not have been optimal for pregnancy. The mean time to estrus after implant removal and the time of insemination were evaluated. Heifers pregnant at the first service had a shorter time to estrus (32.11 +/- 1.6 h, P=0.13), a longer mean interval from the start of estrus to insemination (12.10 +/- 1.2 h, P = 0.16) and a positive mean interval between the end of standing estrus and the time of insemination (3.17 +/-1.7 h, P=0.19) than heifers not conceiving at the synchronized estrus (38.5 +/- 2.1, 7.42 +/- 1.9 h and -2.04 +/- 2.1 h, respectively). Breed differences were observed in estrus durations (Angus 8.52 +/- 1.2 h, Brahman 6.65 +/- 1.2 h, crossbred 11.90 +/- 1.2 h; P = 0.03), number of mounts (19 +/- 3.6, 25 +/- 5.4, 37 +/- 5.5, respectively; P=0.02) and gestation length (281 +/- 1.2, 291 +/- 1.8, 286 +/- 1.1 d, respectively; P = 0.001).