Ectoparasitic Argulus coregoni (Crustacea: Branchiura) hedge their bets – studies on egg hatching dynamics

Unpredictability in the temporal availability of susceptible hosts is likely to act as a selection pressure affecting the life history strategies of parasites. In highly variable environments the future of the lineage can be secured by spreading the risk, for example, by producing descendants that differ in their timing of emergence. Counter to this, in predictable environments a single "best-adapted" phenotype is expected. We asked whether ectoparasitic Argulus coregoni egg hatching pattern can be explained as a genetically canalized individual trait; an instance of phenotypic plasticity or bet-hedging. We collected egg clutches laid by individual A. coregoni females in early and late reproductive period of the lice population and randomized the clutches within 3 treatments. Intra- and inter-clutch variability in the hatching dynamics of A. coregoni eggs was monitored and the reproductive potential assessed. On average A. coregoni females laid 317 (SD±176.6) eggs. We found that the plasticity in the hatching dynamics among A. coregoni eggs was remarkable. Noticeable peaks in hatching were followed each of the repeated artificial "winter treatments" in 1°C. Repeated 2 weeks cold treatments induced relatively bigger hatching peaks than 2 days cold treatments compared to controls at room temperature. However, in all treatments, egg clutches hatched through an extended period of 7 months on average and the total hatching percentages were similar. We found that intra-clutch variability in hatching among eggs laid by single A. coregoni females was greater than inter-clutch variability. Our data support the predictions of the adaptive bet-hedging strategy in relation to egg-hatching dynamics. Response to cooling and bet-hedging may be adaptive for such species like A. coregoni since by synchronizing the life-cycle with the seasonal environment will assist transmission and parasite fitness.     

The corpus luteum of the guinea pig. IV. Fine structure of macrophages during pregnancy and postpartum luteolysis, and the phagocytosis of luteal cells.

Little information is available on the ultrastructure of macrophages in the corpus luteum or their importance in the regression of luteal tissue. In the present study, the fine structure of activated luteal macrophages during pregnancy and the postpartum period was examined by electron microscopy of guinea pig ovaries fixed by vascular perfusion. In these corpora lutea, macrophages can readily be distinguished from luteal cells. Activated macrophages typically display three prominent inclusions in their cytoplasm: (1) heterophagic vacuoles, (2) distinctive large dense inclusions, and (3) large and small electron-lucent vacuoles. In addition, they contain numerous smaller lysosome-like dense bodies. Activated macrophages in corpora lutea also characteristically show many surface protrusions, such as processes, folds or pseudopodia, which often occur in close contact with nearby luteal cells. Generally, nuclei of macrophages are irregular in shape and display a dense border of heterochromatin, thus differing from those of luteal cells. Macrophages seem to be most abundant in regressing corpora lutea, where they commonly display heterophagic vacuoles containing recognizable luteal cell fragments, evidence that these phagocytes ingest senescent luteal cells. The digestion of luteal cell components in heterophagic vacuoles presumably gives rise to the distinctive large dense inclusions typically seen in macrophages. The findings of this study indicate that macrophages play a central role in luteolysis by phagocytizing luteal cells or their remnants. They therefore appear to bring about the reduction in volume of the corpus luteum that occurs as this tissue regresses. These results taken together with those previously published (Paavola, '78) further indicate that breakdown of the corpus luteum during postpartum luteolysis in guinea pigs involves both autophagy and heterophagy.     

Use of Symbiosis Products from Integrated Pulp and Paper and Carbon Steel Mills: Legal Status and Environmental Burdens

This study assesses the policy/legal status of both multistream residues and potential secondary products (“symbiosis products”) and whether there could be environmental benefits associated with the utilization of residues from integrated pulp and paper and carbon steel mills as raw materials for such secondary products. Waste‐related European Union (EU) and Finnish policy and legal instruments were reviewed to identify potential constraints for, and suggested next steps in, the development of potential process industry residue‐based symbiosis products. The products were soil amendment pellets, low‐grade concrete, and mine filler. A global warming potential (GWP) assessment and an exergy analysis were applied to these potential symbiosis products. Some indicative GWP calculations of greenhouse gas emissions associating similar and/or analogous products based on virgin primary raw materials, more energy‐intensive processes, and the alternative treatment of these residues as wastes are also presented. This study addresses GWP, exergy, and legal aspects in a holistic manner to determine the potential environmental benefits of secondary products within the EU legal framework. The GWP assessment and exergy analysis indicate that the utilization of multistream residues causes very low environmental burdens in terms of GWP. The utilization option can have potential environmental benefits in terms of GWP through process replacement and avoided landfilling and waste treatment impacts, as well as potentially through emission reductions from product replacement if suitable and safe applications can be identified. Waste regulation does not define the legal requirements under which utilizing residues in such novel concepts as introduced in this study would be possible, nor how waste status could be removed and product‐based legislation be applied to the potential products instead.     

Adiponectin and peptide YY in the fasting blue fox (Alopex lagopus)

Adiponectin (Acrp30) and peptide YY (PYY) are weight-regulatory hormones participating in the control of energy homeostasis. This study investigated the effects of long-term wintertime fasting on plasma Acrp30 and PYY levels in the carnivorous blue fox, a farm-bred variant of the arctic fox (Alopex lagopus). Plasma Acrp30 and PYY concentrations were determined with radioimmunoassays during a 22-day period of fasting, which led to a 20.3% reduction in body mass of the animals (n=32). Sixteen fed blue foxes served as the control group. Acrp30 and PYY were present in blue fox plasma at similar or lower levels as reported previously for other mammals. Fasting had no acute effects on Acrp30 or PYY concentrations of the blue foxes. However, the Acrp30 levels of the fasted blue foxes were 24%-48% higher than in the fed animals between days 8-22 of fasting. Fasted blue foxes also had 6.2-fold higher plasma PYY concentrations after 15 days of fasting. Acrp30 and PYY seem to play roles in the body weight-regulation of the blue fox during long-term fasting, but their specific functions and physiological significance remain to be determined.     

Derivation of three new human embryonic stem cell lines

Human embryonic stem cells are pluripotent cells capable of extensive self-renewal and differentiation to all cells of the embryo proper. Here, we describe the derivation and characterization of three Sydney IVF human embryonic stem cell lines not already reported elsewhere, designated SIVF001, SIVF002, and SIVF014. The cell lines display typical compact colony morphology of embryonic stem cells, have stable growth rates over more than 40 passages and are cytogenetically normal. Furthermore, the cell lines express pluripotency markers including Nanog, Oct4, SSEA3 and Tra-1-81, and are capable of generating teratoma cells derived from each of the three germ layers in immunodeficient mice. These experiments show that the cell lines constitute pluripotent stem cell lines.     

Selective fatty acid mobilization in the American mink (Mustela vison) during food deprivation

The mobilization of fatty acids (FAs) during food deprivation is a selective process in laboratory rodents and humans. The site-specific differences in adipose tissue functions - e.g. energy storage versus insulation - should also affect the use of different FAs. To study this, 16 female minks were randomly assigned into the control group or fasted for 5 days. Preferential mobilization of n-3 polyunsaturated FAs (PUFAs) during fasting caused a decrease in the n-3/n-6 PUFA ratio in fat and liver. In addition, the minks utilized short-chain FAs efficiently in all fat depots, but long-chain FAs - 20:0, 20:1n-11, 20:1n-9, 22:1n-11 and 24:1n-9 - were preserved. The number of double bonds in the FA chain correlated positively with mobilization rate in the retroperitoneal fat. The observed negative correlation between mobilization rate and the location of the first double bond from the methyl end may be due to peroxisomal chain-shortening of long-chain FAs and not the double bond position per se. As a result, minks are able to preserve a low melting point and fluidity of the subcutaneous fat depots, which would be essential to a Northern semi-aquatic mammal.     

Physiological adaptations to fasting in an actively wintering canid, the Arctic blue fox (Alopex lagopus)

This study investigated the physiological adaptations to fasting using the farmed blue fox (Alopex lagopus) as a model for the endangered wild arctic fox. Sixteen blue foxes were fed throughout the winter and 32 blue foxes were fasted for 22 d in Nov-Dec 2002. Half of the fasted blue foxes were food-deprived again for 22 d in Jan-Feb 2003. The farmed blue fox lost weight at a slower rate (0.97-1.02% body mass d(-1)) than observed previously in the arctic fox, possibly due to its higher initial body fat content. The animals experienced occasional fasting-induced hypoglycaemia, but their locomotor activity was not affected. The plasma triacylglycerol and glycerol concentrations were elevated during phase II of fasting indicating stimulated lipolysis, probably induced by the high growth hormone concentrations. The total cholesterol, HDL- and LDL-cholesterol, urea, uric acid and total protein levels and the urea:creatinine ratio decreased during fasting. Although the plasma levels of some essential amino acids increased, the blue foxes did not enter phase III of starvation characterized by stimulated proteolysis during either of the 22-d fasting procedures. Instead of excessive protein catabolism, it is liver dysfunction, indicated by the increased plasma bilirubin levels and alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase activities, that may limit the duration of fasting in the species.     

Synthesis and CB1 receptor activities of dimethylheptyl derivatives of 2-arachidonoyl glycerol (2-AG) and 2-arachidonyl glyceryl ether (2-AGE)

Results from a factor analysis and activity studies of commercially available endocannabinoid-type compounds set the starting point for the current study where dimethylheptyl (DMH) analogues of two endocannabinoids, 2-arachidonoyl glycerol (2-AG) and 2-arachidonyl glyceryl ether (2-AGE), were synthesized and their ability to activate the CB1 receptors was determined by the [35S]GTPgammaS binding assay using rat cerebellar membranes. The main goal of the study was to examine how the DMH end tail affects the activity properties of 2-AG (1) and its stable ether (2) and urea analogues (5). The importance of the chain length was also explored by synthesizing 2-AG and 2-AGE derivatives (3 and 4) possessing the chain length C21 instead of C22. Replacement of the pentyl end chain with the DMH resulted in distinct potency decrease as compared to the reference compounds. The modification did not have such a strong impact on the efficacy values. In fact, the efficacy of the derivatives of 2-AGE (2 and 4) was comparable or even improved. Introducing a more stable and hydrophilic urea bond led to a dramatic decrease in biological activity.