Regulation of hair follicle development by the TNF signal ectodysplasin and its receptor Edar

X-linked and autosomal forms of anhidrotic ectodermal dysplasia syndromes (HED) are characterized by deficient development of several ectodermal organs, including hair, teeth and exocrine glands. The recent cloning of the genes that underlie these syndromes, ectodysplasin (ED1) and the ectodysplasin A receptor (EDAR), and their identification as a novel TNF ligand-receptor pair suggested a role for TNF signaling in embryonic morphogenesis. In the mouse, the genes of the spontaneous mutations Tabby (Ta) and downless (dl) were identified as homologs of ED1 and EDAR, respectively. To gain insight into the function of this signaling pathway in development of skin and hair follicles, we analyzed the expression and regulation of Eda and Edar in wild type as well as Tabby and Lef1 mutant mouse embryos. We show that Eda and Edar expression is confined to the ectoderm and occurs in a pattern that suggests a role of ectodysplasin/Edar signaling in the interactions between the ectodermal compartments and the formation and function of hair placodes. By using skin explant cultures, we further show that this signaling pathway is intimately associated with interactions between the epithelial and mesenchymal tissues. We also find that Ta mutants lack completely the placodes of the first developing tylotrich hairs, and that they do not show patterned expression of placodal genes, including Bmp4, Lef1, Shh, Ptch and Edar, and the genes for beta-catenin and activin A. Finally, we identified activin as a mesenchymal signal that stimulates Edar expression and WNT as a signal that induces Eda expression, suggesting a hierarchy of distinct signaling pathways in the development of skin and hair follicles. In conclusion, we suggest that Eda and Edar are associated with the onset of ectodermal patterning and that ectodysplasin/edar signaling also regulates the morphogenesis of hair follicles.     

Polyunsaturated fatty acids in serum lipids of reindeer during the close postnatal period

We examined serum fatty acid composition in reindeer during the close postnatal period (from <8 h to 3 weeks) by using maternal serum as a reference point and focusing on the proportions of polyunsaturated fatty acids (PUFAs) in serum lipids. A striking dissimilarity was found in the serum PUFAs between the neonatals and their mothers. In particular, the proportions of linoleic acid (18:2) and α-linolenic acid in serum cholesteryl esters and phospholipids of the newborn reindeer were significantly lower than those of the mothers. Furthermore, serum phospholipids of the newborns had lower arachidonic acid and docosapentaenoic acid but higher docosahexaenoic acid proportions than the maternal phospholipids. Although the proportions of the principal C18 PUFAs were low in reindeer milk, they increased sharply in serum cholesteryl esters and phospholipids of the calves during the first few days after birth. In particular, there were significant positive correlations in the proportions of 18:2 between serum and milk lipids. We conclude that the proportions of the serum C18 PUFAs are low in the newborn reindeer, but they are increased during the close perinatal period by a rate which suggests an efficient mechanism for selective retention of these fatty acids from milk lipids. Accepted: 10 August 1998     

Development of Baltic Sea zooplankton in the presence of a toxic cyanobacterium: a mesocosm approach

Cyanobacteria blooms are common in the Baltic Sea and are consideredto be a poor food source and sometimes toxic to zooplankton.Most experiments demonstrating harmful effects have been short-termincubations with monocultures or simple mixtures of food. Inthis study, a mesocosm approach was used to examine zooplanktonresponses over generation timescales. A toxic strain of thecyanobacterium Nodularia spumigena was added to bag enclosuresof ambient water. The initial mesozooplankton concentrationwas either reduced by prescreening the water or enriched withlocally caught zooplankton. Experiments ran for 15 days, longenough to monitor reproductive success and development of thenext mesozooplankton generations. There was no major harmfuleffect on the zooplankton assemblage, even though the concentrationof the toxin nodularin was in the upper range of field observations.The copepod Eurytemora affinis, rotifers Synchaeta spp. andthe cladoceran Bosmina longispina maritima were able to developand reproduce successfully in the presence of N. spumigena.The only species showing impaired recruitment was the copepodAcartia bifilosa. The general lack of population level effectsfrom N. spumigena in this study can be reconciled with previousobservations of adverse effects. Cyanobacteria alone may bepoor food and toxic to zooplankton, but in the mesocosms a richassemblage of microbiota developed, similar to that associatedwith blooms in the field. We suggest that, in the context ofotherwise food-depleted summer situations in the open BalticSea, zooplankton can derive benefit from cyanobacteria bloomassemblages.     

Two missense mutations in melanocortin 1 receptor (MC1R) are strongly associated with dark ventral coat color in reindeer (Rangifer tarandus)

The protein‐coding region of melanocortin 1 receptor (MC1R) was sequenced to identify potential variation affecting coat color in reindeer (Rangifer tarandus). A T→C sequence variation at nucleotide position 218 (c.218T>C) causing an amino acid (aa) change from methionine to threonine at aa position 73 (p.Met73Thr) was identified. In addition, a T→G sequence variation was found at nucleotide position 839 (c.839T>G), causing phenylalanine to be exchanged by cysteine at aa position 280 (p.Phe280Cys). The two sequence variants (c.218C and c.839G) were found to be closely associated with a darker belly coat compared with animals not having any of these two variants. The aa acid change p.Met73Thr affects the same position as p.Met73Lys previously reported to give constitutive activation of MC1R in black sheep (Ovis aries), whereas p.Phe280Cys is identical to one of two variants previously reported to be associated with dark coat color in Arctic fox (Alopex lagopus), supporting that the two variants found in reindeer are functional. The complete absence of Thr73 and Cys280 among the 51 wild reindeer analyzed provides some evidence that these variants are more common in the domestic herds.     

APOA5 gene variants, lipoprotein particle distribution, and progression of coronary heart disease: results from the LOCAT study

Animal and human studies support a role for apolipoprotein A-V (apoA-V) in triglyceride (TG) metabolism. We examined the relationship of APOA5 -1131T>C and S19W with lipid subfractions and progression of atherosclerosis in the Lopid Coronary Angiography Trial. Compared with -1131TT men (n = 242), carriers of the -1131C allele (n = 54) had significantly higher total TG (P = 0.03), reflected in significantly increased VLDL mass [higher VLDL-TG, VLDL-cholesterol, VLDL-protein, and surface lipids (all P < 0.05)]. Because apoB levels were unaffected by genotype, this suggests an increase in VLDL size and not number. Compared with 19SS men (n = 268), 19W carriers (n = 44) had higher intermediate density lipoprotein (IDL)-TG, IDL-cholesterol (P = 0.04), and IDL-surface components [free cholesterol (P = 0.005) and phospholipids (P = 0.017)] but not protein content, suggesting an increase in IDL lipid enrichment resulting in an increase in IDL size. 19W carriers also showed a trend toward increased progression of atherogenesis, as measured by change in average diameter of segments (-0.46 +/- 0.011 mm compared with -0.016 +/- 0.006 mm) in 19SS men (P = 0.08). There was no effect of genotype on the response of these parameters to gemfibrozil treatment. These results shed new light on the role of APOA5 variants in TG metabolism and coronary heart disease risk.     

Doppler radar detection of exceptional mass-migration of aphids into Finland

Our objective was to detect mass migrations of insects of economic significance by insect traps and a Doppler weather radar. Migrants were sampled by suction traps, tow nets and light traps in the Helsinki region. We used radar to observe the migrating insects, and trajectories to backtrack mass migrations of aphids (Homoptera, Aphididae) in spring 1988. The aphid migrations were clearly observed in trap catches and by radar. The first migration, mainly involving Euceraphis betulae, occurred on 18 May and was tracked back to northern Poland. The second migration, mainly of Rhopalosiphum padi (a serious pest of small-grain cereals), occurred 3 days later and was tracked back to a large area covering Latvia and western Russia south of St Petersburg. The third migration included both E. betulae and R. padi, and took place on 30 May. It originated from Estonia. Neither trap nor radar data provide exact quantitative information on migrations. Trapping efficiency depends strongly on wind speed and insect size. Radar echo intensity is very strongly related to the sizes of insects in the large volume of air measured, and the sizes are not known accurately. Weather data, especially temperature, can be used in predicting the development of aphids, and air-parcel trajectories in estimating the source areas of migrants. These methods for forecasting aphid migrations, combined with radar observations, are useful for warning purposes and to intensify insect trapping. This would contribute to more efficient agricultural pest management. Received: 11 March 2000 / Revised: 24 April 2000 / Accepted: 26 April 2000     

Depletion of intracellular Ca2+ by caffeine and ryanodine induces apoptosis of chinese hamster ovary cells transfected with ryanodine receptor

Recent studies have suggested a central role for Ca(2+) in the signaling pathway of apoptosis and certain anti-apoptotic effects of Bcl-2 family of proteins have been attributed to changes in intracellular Ca(2+) homeostasis. Here we report that depletion of Ca(2+) from endoplasmic reticulum (ER) leads to apoptosis in Chinese hamster ovary cells. Stable expression of ryanodine receptor (RyR) in these cells enables rapid and reversible changes of both cytosolic Ca(2+) and ER Ca(2+) content via activation of the RyR/Ca(2+) release channel by caffeine and ryanodine. Sustained depletion of the ER Ca(2+) store leads to apoptosis in Chinese hamster ovary cells, whereas co-expression of Bcl-xL and RyR in these cells prevents apoptotic cell death but not necrotic cell death. The anti-apoptotic effect of Bcl-xL does not correlate with changes in either the Ca(2+) release process from the ER or the capacitative Ca(2+) entry through the plasma membrane. The data suggest that Bcl-xL likely prevents apoptosis of cells at a stage downstream of ER Ca(2+) release and capacitative Ca(2+) entry.     

Expression of mammalian RF-amide peptides neuropeptide FF (NPFF), prolactin-releasing peptide (PrRP) and the PrRP receptor in the peripheral tissues of the rat

The mRNA expression of neuropeptide FF (NPFF), prolactin-releasing peptide (PrRP) and the UHR-1/GPR10 receptor were examined using in situ hybridization in rat peripheral tissues. In the hypophysis, modest expression of PrRP and receptor mRNA were seen in the anterior lobe. The trigeminal ganglion was devoid of expression signals. PrRP and UHR-1/GPR10 receptor mRNA:s were found in the adrenal medulla and PrRP mRNA was found in the pancreas. NPFF mRNA was detected in the spleen. In the testis and epididymis, PrRP and UHR-1/GPR10 receptor mRNA:s were detected. The results suggest a limited expression of mammalian RF-amide peptides in the peripheral organs.     

Seasonality of leptin levels in the BAT of the common shrew (Sorex araneus)

Leptin concentrations in the interscapular brown adipose tissue (IBAT) of the common shrew (Sorex araneus) were measured in different seasons. The leptin concentrations in IBAT were much higher than in the liver, where leptin is supposed to be of blood origin. In the heart muscle no detectable amount of leptin was found. There were clear seasonal variations in the leptin concentrations in IBAT. Leptin levels in IBAT were the lowest in November at the beginning of the winter. The concentrations increased, however, strongly after the onset of the permanent snow cover, and the highest concentrations were measured in December-January, when the weight of the animals was very low. In April-May, at the time when shrews attain sexual maturity, leptin concentrations in IBAT were lower than in the mid-winter, but significantly higher than in November. In overwintered adults the leptin concentrations were at the same level as in nonwintered subadults. Leptin originating from BAT may inform the central nervous system about the amount of nonshivering thermogenesis as well as the amount of feeding necessary for survival in the winter months.     

Adaptations to fasting in the American mink (Mustela vison): carbohydrate and lipid metabolism

The aim of this study was to investigate whether the actively wintering American mink Mustela vison is strictly dependent on continuous food availability or if it has evolved physiological adaptations to tolerate nutritional scarcity. Fifty farm-bred male minks were divided into a fed control group and four experimental groups fasted for 2, 3, 5 or 7 days. The rate of weight loss was several-fold higher (1.5-3.2% day(-1)) in the mink than recorded previously in larger carnivores utilizing passive wintering strategies. The minks remained normoglycaemic, although their liver glycogen stores and glucose-6-phosphatase activities decreased during fasting. Adipose tissue constituted approximately 36% of their body mass after 7 days of food deprivation. Intra-abdominal fat, especially retroperitoneal but also mesenteric adipose tissue, were the most important fat depots to be hydrolyzed, but the ability of the mink to utilize its body lipids during fasting may be limited. The increased liver size, hepatic triacylglycerol accumulation and increases in the activities of plasma aminotransferases indicated liver dysfunction. Food deprivation also affected the red blood cell indices, and the blood monocyte and lymphocyte counts decreased suggesting immunosuppression during fasting. The results of the present study suggest that the mink has not evolved sophisticated adaptations to wintertime fasting.