Growth and reproduction in the Icelandic common seal (Phoca vitulina L., 1758)

Length, weight and maturity were studied in relation to age in the common seal (Phoca vitulina vitulina L., 1758), collected during the periods 1979-1983 and 1990-2000 in Icelandic waters. The maximum age of common seal observed was 36 years for females and 30 years for males. For common seal females and males, asymptotic length and weight were 161 cm and 93 kg and 174 cm and 97 kg, respectively, showing slight sexual dimorphism in size. The condition of adult females, measured as fat thickness at the lower end of the sternum, was lower in the period 1979-1983 than in 1990-2000 during June-September, the breeding and mating time of the Icelandic common seal. Males reached sexual maturity between 5 and 7 years, whereas 50% of females did so at age 4 years. Including the length and age interaction term in the logistic regression model for the maturity of females significantly improved it. Thus, body size matters in the onset of maturity. The mean birthing date for the Icelandic common seal was found to be in early June. A comparison of animals collected in the two periods 1979-1983 and 1990-2000 did not show significant differences in growth and the average age of sexual maturity for either males or females. The observed decline of the Icelandic common seal population is most probably caused by increased mortality, due to exploitation and accidental by-catch in gill-nets, rather than a decrease in fecundity.     

Effects of anoxia and low pH on organic ion transport and electrolyte distribution in harbor seal (Phoca vitulina) kidney slices

Summary The present study was undertaken to examine the effects of anoxia and/or low pH on active organic ion transport and tissue water and electrolyte distribution in freshly prepared cortical slices from harbor seal and rat kidneys.p-Aminohippurate (PAH) and tetraethylammonium (TEA) were used as a representative organic anion and cation, respectively. The slice uptake of PAH was not influenced by the incubation medium pH over a range of 5.0–7.5 in the harbor seal while it was very sensitive to the medium pH in the rat, decreasing significantly with reductions in pH (Fig. 1). Although the TEA uptake decreased in anoxia in both species, it decreased considerably less in the harbor seal than in the rat (40% vs 74%) (Fig. 2). However, in contrast to the PAH transport system, the TEA uptake decreased significantly at low pH in both species. The magnitudes of increase in intracellular Na and of decrease in intracellular K in anoxia were consistently less in the harbor seal than in the rat, especially at low pH (Fig. 3). However, the pH dependence of Na–K-ATPase activity of the crude renal cortical homogenate was not different between the two species (Fig. 4). These results, together with the previous finding on the anoxic tolerance of the renal organic anion transport system, indicate that (1) the overall anoxic tolerance of active renal transport systems for both organic anions and cations is greater in the harbor seal than in the rat, and (2) the renal organic anion (but not cation) transport system is resistant to low pH in the harbor seal.Abbreviations 2,4-D 2,4-dichlorophenoxyacetate - KRP Krebs-Ringer phosphate buffer - PAH para-aminohippurate - S/M slice to medium concentration ratio - TEA tetraethylammonium     

Rigid matrix supports osteogenic differentiation of stem cells from human exfoliated deciduous teeth (SHED)

Stem cell fate can be induced by the grade of stiffness of the extracellular matrix, depending on the developed tissue or complex tissues. For example, a rigid extracellular matrix induces the osteogenic differentiation in bone marrow derived mesenchymal stem cells (MSCs), while a softer surface induces the osteogenic differentiation in dental follicle cells (DFCs). To determine whether differentiation of ectomesenchymal dental precursor cells is supported by similar grades of extracellular matrices (ECMs) stiffness, we examined the influence of the surface stiffness on the proliferation and osteogenic differentiation of stem cells from human exfoliated deciduous teeth (SHED). Cell proliferation of SHED was significantly decreased on cell culture surfaces with a muscle-like stiffness. A dexamethasone-based differentiation medium induced the osteogenic differentiation of SHED on substrates of varying mechanical stiffness. Here, the hardest surface improved the induction of osteogenic differentiation in comparison to that with the softest stiffness. In conclusion, our study showed that the osteogenic differentiation of ectomesenchymal dental precursor cells SHED and DFCs are not supported by similar grades of ECM stiffness.     

Ontogeny of humoral immunity in northern elephant seal (Mirounga angustirostris) neonates

Northern elephant seal (NES) serum concentrations of total immunoglobulin (Ig) G, an IgG sub-class, and an IgM-like protein were determined by capture immunoassay using three monoclonal antibodies with specificities for Ig of members of the Phocidae pinniped family. These assays were calibrated for use with NES sera using affinity column purified Ig. Concentrations of these Ig populations were estimated in adult female sera sampled at two time points during the lactation period, as well as sera from their pups collected during the first 5 weeks after birth. In pups, concentrations of the IgM-like protein was found to increase rapidly post-partum. In some individuals, values reached mean concentrations within 10–14 days. In addition, rapid increases in pup total IgG and IgG sub-class concentrations were also observed. Collectively, these findings suggest that the majority of post-partum increases in serum Ig can be accounted for by de-novo synthesis.     

A descriptive and comparative study of the deciduous dentition of prehistoric Ohio Valley Amerindians

The deciduous dentition of 58 individuals from groups of prehistoric Ohio Valley Amerindians (2,000 B.C.-1,600 A.D.) was measured for antero-posterior and bucco-lingual dimensions and scored for morphological characteristics and macroscopic pathology. Only five dimensions of the posterior teeth and the frequency of severe linear enamel hypoplasia showed significant differences in the groups. In all cases focal agriculturalists exhibited smaller teeth and a higher frequency of severe linear enamel hypoplasia. These findings are explained as the result of changing diet and food preparation techniques, and/or sampling bias in the earlier burial cult groups where primarily higher status individuals may be the representatives. Comparison of metric and morphological characteristics of the deciduous dentition in the prehistoric Amerindians and roughly contemporaneous European groups indicates morphological characteristics are the better means of discrimination.     

Male mating success in an aquatically mating pinniped, the harbour seal (Phoca vitulina), assessed by microsatellite DNA markers

Similar to many other pinniped species, harbour seals ( Phoca vitulina ) mate exclusively at sea. Here we present the first attempt to measure male mating success in an aquatically mating pinniped. Male mating success was estimated by paternity analysis in two cohorts of pups born at Sable Island, Nova Scotia, Canada, using microsatellite DNA markers. The genotypes of 275 pups born in 1994 and 1995 were compared to those of 90 candidate males at six microsatellite loci using a likelihood approach to resolve paternity. Paternity could be assigned for two, 22, 40 and 85 pups at confidence levels of 95, 80, 65 and 50%, respectively. Most successful males were assigned the paternity of a single offspring, suggesting a low variance in male mating success relative to most pinniped species. The proportion of paternal half sibs within cohorts and between maternally related sibs estimated by maximum likelihood were not significantly different from zero. It is thus unlikely that most offspring were sired by a small number of highly successful unsampled males, and that female harbour seals do not usually exhibit fidelity to the same male in sequential breeding seasons. A low level of polygyny in Sable Island harbour seals is consistent with predictions based on their breeding ecology, as females are highly mobile and widely dispersed in the aquatic mating environment at Sable Island.     

The complete primary structure of the marine carnivora, galapagoes fur seal (Arctocephalus galapagoensis, Otariidae) hemoglobins

The complete primary structure of the two hemoglobin components of the fur seal (Arctocephalus galapagoensis) is presented. The two components (HbI and HbII) occur in nearly equal amounts and have identical -chains; whereas the two -chains (I/II) differ by six exchanges Ile/Val, Met/Thr, Ser/Ala, Pro/His, Lys/Gly, and Thr/Ala at positions 10, 34, 35, 50, 78, and 131, respectively. The components were isolated by DEAE-Sephacel chromatography and were separated into the globin chains by RP-HPLC on a column of Nucleocil-C4. The sequences have been determined by Edman degradation in liquid- and gas-phase sequencer, using the native chains and tryptic peptides. The sequences compared with those of other Carnivora species and an adult human globin chains. An identical -chain is found in fur seal and walrus, whereas larger differences were found between I and II compared to -chains.Deceased on May 27, 1989.     

Impaired neurite development associated with mitochondrial dysfunction in dopaminergic neurons differentiated from exfoliated deciduous tooth-derived pulp stem cells of children with autism spectrum disorder

Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder characterized by impaired social interactions, restrictive interests, and repetitive stereotypic behaviors. Among the various mechanisms underlying the pathogenesis of ASD, dysfunctions of dopaminergic signaling and mitochondria have been hypothesized to explain the core symptoms of children with ASD. However, only a few studies focusing on the pathological association between dopaminergic neurons (DN) and mitochondria in ASD have been performed using patient-derived stem cells and in vitro differentiated neurons. Stem cells from human exfoliated deciduous teeth (SHED) are neural crest-derived mesenchymal stem cells present in the dental pulp of exfoliated deciduous teeth; these cells can differentiate into dopaminergic neurons (DN) in vitro. This study aimed to investigate the pathological association between development of DN and mitochondria in ASD by using SHED as a disease- or patient-specific cellular model. The SHED obtained from three children with ASD and three typically developing children were differentiated into DN, and the neurobiology of these cells was examined. The DN derived from children with ASD showed impaired neurite outgrowth and branching, associated with decreased mitochondrial membrane potential, ATP production, number of mitochondria within the neurites, amount of mitochondria per cell area and intracellular calcium level. In addition, impaired neurite outgrowth and branching of ASD-derived DN were not improved by brain-derived neurotrophic factor (BDNF), suggesting impairment of the BDNF signaling pathway in ASD. These results imply that intracerebral dopamine production may have decreased in these children. The earliest age at which deciduous teeth spontaneously exfoliate in humans, and SHED can be noninvasively collected, is approximately 6 years. Our results suggest that in vitro analysis of SHED-derived DN obtained from children with ASD provides neurobiological information that may be useful in determining treatment strategies in the early stages of ASD.     

Folic acid-mediated mitochondrial activation for protection against oxidative stress in human dental pulp stem cells derived from deciduous teeth

Enzymatic antioxidant systems, mainly involving mitochondria, are critical for minimizing the harmful effects of reactive oxygen species, and these systems are enhanced by interactions with nonenzymatic antioxidant nutrients. Because fetal growth requires extensive mitochondrial respiration, pregnant women and fetuses are at high risk of exposure to excessive reactive oxygen species. The enhancement of the antioxidant system, e.g., by nutritional management, is therefore critical for both the mother and fetus. Folic acid supplementation prevents homocysteine accumulation and epigenetic dysregulation associated with one-carbon metabolism. However, few studies have examined the antioxidant effects of folic acid for healthy pregnancy outcomes. The purpose of this study was to elucidate the association between the antioxidant effect of folic acid and mitochondria in undifferentiated cells during fetal growth. Neural crest-derived dental pulp stem cells of human exfoliated deciduous teeth were used as a model of undifferentiated cells in the fetus. Pyocyanin induced excessive reactive oxygen species, resulting in a decrease in cell growth and migration accompanied by mitochondrial fragmentation and inactivation in dental pulp stem cells. This damage was significantly improved by folic acid, along with decreased mitochondrial reactive oxygen species, PGC-1α upregulation, DRP1 downregulation, mitochondrial elongation, and increased ATP production. Folic acid may protect undifferentiated cells from oxidative damage by targeting mitochondrial activation. These results provide evidence for a new benefit of folic acid in pregnant women and fetuses.     

Dap ( D efective a leurone p igmentation) mutations affect maize aleurone development

Dap (Defective aleurone pigmentation) is the designation for mutations in maize that give rise to a characteristic dappled endosperm phenotype, consisting of patches of purple tissue, of variable size and shape, on a yellow background. Features shared by all Dap mutants are: dominant expression when they are maternally derived, lack of expression or transmission when they originate from pollen, failure to recover homozygous Dap genotypes, reduced frequency of Dap seeds in the progeny of outcrosses of Dap/+ females, association of the dappled phenotype with reduction in seed size. The mutants so far tested, six in all, can be grouped into two classes, one including male-transmissible (MT) isolates not expressed in the endosperm if their contribution is paternal, and a second class of isolates (NMT) that are permanently lost following paternal transmission. We suggest that the NMT mutations are on a chromosome that carries an intercalary deletion. Assuming linkage between the mutant and the deletion, selection against the deficient chromosome during male gametogenesis would account for the failure to recover Dap seeds in the progeny of Dap/+ male parents. We have obtained genetic evidence supporting this hypothesis. This interpretation, however, does not apply to MT alleles. For these, other mechanisms, such as imprinting and/or dosage effects may be proposed. The mutable pattern in the endosperm to which all Dap mutants give rise is an intriguing phenotype which remains to be clarified. An unexpected finding is that aleuronic and subaleuronic cells corresponding to the colourless areas are abnormal in shape and anthocyanin biosynthesis is blocked in these cells. This finding calls for further investigation in light of a possible connection between flavonoid precursors and cell shape. Received: 2 January 1997 / Accepted: 26 May 1997     

The proprotein convertase amontillado (amon) is required during Drosophila pupal development

Peptide hormones governing many developmental processes are generated via endoproteolysis of inactive precursor molecules by a family of subtilisin-like proprotein convertases (SPCs). We previously identified mutations in the Drosophila amontillado (amon) gene, a homolog of the vertebrate neuroendocrine-specific Prohormone Convertase 2 (PC2) gene, and showed that amon is required during embryogenesis, early larval development, and larval molting. Here, we define amon requirements during later developmental stages using a conditional rescue system and find that amon is required during pupal development for head eversion, leg and wing disc extension, and abdominal differentiation. Immuno-localization experiments show that amon protein is expressed in a subset of central nervous system cells but does not co-localize with peptide hormones known to elicit molting behavior, suggesting the involvement of novel regulatory peptides in this process. The amon protein is expressed in neuronal cells that innervate the corpus allatum and corpora cardiaca of the ring gland, an endocrine organ which is the release site for many key hormonal signals. Expression of amon in a subset of these cell types using the GAL4/UAS system in an amon mutant background partially rescues larval molting and growth. Our results show that amon is required for pupal development and identify a subset of neuronal cell types in which amon function is sufficient to rescue developmental progression and growth defects shown by amon mutants. The results are consistent with a model that the amon protein acts to proteolytically process a diverse suite of peptide hormones that coordinate larval and pupal growth and development.     

Molecular cloning of the lectin and a lectin-related protein from common Solomon's seal (Polygonatum multiflorum)

The most prominent protein ofPolygonatum multiflorum (common Solomon's seal) rhizomes has been identified as a mannose-binding lectin. Analysis of the purified lectin demonstrated that it is a tetramer of four identical subunits of 14 kDa. Molecular cloning further revealed that the lectin from this typical Liliaceae species belongs to the superfamily of monocot mannose-binding proteins. Screening of cDNA libraries constructed with RNA isolated from buds, leaves and flowers ofP. multiflorum also yielded cDNA clones encoding a protein, which contains two tandemly arranged domains with an obvious sequence homology to the mannose-binding lectins. Molecular modelling of thePolygonatum lectin and lectin-related protein indicated that the three-dimensional structure of both proteins strongly resembles that of the snowdrop lectin. In addition, this approach suggested that the presumed carbohydrate-binding sites of the lectin can accommodate a mannose residue whereas most of the carbohydratebinding sites of the lectin-related protein cannot.Abbreviations GNA Galanthus nivalis agglutinin - HCA hydrophobic cluster analysis - LECPMA cDNA clone encoding PMA - PM30 30 kDa protein isolated fromPolygonatum multiforum - PMA Polygonatum multiflorum agglutinin - PMLRP Polygonatum multiflorum lectin-related protein     

Tooth Replacement in Late Jurassic Dryolestidae (Eupantotheria, Mammalia)

The discovery of juvenile dentitions of late Jurassic (Kimmeridgian) Dryolestidae (Eupantotheria, Mammalia) from Guimarota, Portugal, yields for the first time information on the mode of tooth replacement in therian mammals prior to the dichotomy of placentals and marsupials. As in extant placentals, tooth replacement occurs at all antemolar positions [incisors (I1–I4), canine (C), premolars (P1–P4)]. P1 and P2 have premolariform milk predecessors, whereas the large premolariform third (P3) and fourth premolars (P4) are preceded by molariform deciduous premolars (dP3, dP4). Tooth replacement takes place in two waves, at least in the lower jaw, with I₂, I₄, P₁, and P₃ in the first series and I₁, I₃, C, P₂, and P₄ in the second. P₄ is the last premolar to erupt, and it is present when the sixth molar (M₆) starts to break through. The reduced tooth replacement pattern of marsupials (with only dP3 being replaced postnatally) evolved secondarily from the primitive or plesiomorphic mammalian condition, which was retained in Dryolestidae and Eutheria.     

Sequence and age of eruption of deciduous dentition in the baboon (Papio sp)

A detailed eruption sequence and associated age of eruption for deciduous dentition in baboons (Papio sp) are presented in this paper. The sequence was determined by evaluation and comparison of the number and kinds of teeth present in nine age cohorts comprising the study sample of 88 males and 87 females who ranged in age from birth to 763 days. Eruption was assessed visually as present or absent. Several statistical methods used to derive the ages associated with the eruption sequence are described. The basic eruption sequence in the sample population is: i¹ i₁, i₂, i², \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm c}\limits_{\rm -} {\rm,}\mathop {\rm c}\limits^{\rm -} $\end{document} m¹ (m², m₂), M₁, M¹. Both sexes show the same pattern, with the exception of the second deciduous molar, where males show a sequence of m₂, m₂, while females show the opposite. Posterior dentition shows the greatest gender-specific variation in average age of eruption.