A neonatal polyvisceral failure linked to a de novo homoplasmic mutation in the mitochondrially encoded cytochrome b gene

Mutations within the mitochondrially encoded cytochrome b (MTCYB) gene are heteroplasmic and lead to severe exercise intolerance. We describe an unusual clinical presentation secondary to a novel homoplasmic mutation within MTCYB. The m.15635T > C transition (S297P) was carried by a newborn who presented with a polyvisceral failure. This mutation was responsible for a complex III deficiency. It was homoplasmic in all tissues tested and was undetectable in patient’s mother. Functional analyses, including studies on patient’s cybrid cell lines, demonstrate the pathogenicity of this variant. Our data show that mutations within MTCYB can be responsible for severe phenotype at birth.     

Abeta42 mutants with different aggregation profiles induce distinct pathologies in Drosophila

Aggregation of the amyloid-beta-42 (Abeta42) peptide in the brain parenchyma is a pathological hallmark of Alzheimer's disease (AD), and the prevention of Abeta aggregation has been proposed as a therapeutic intervention in AD. However, recent reports indicate that Abeta can form several different prefibrillar and fibrillar aggregates and that each aggregate may confer different pathogenic effects, suggesting that manipulation of Abeta42 aggregation may not only quantitatively but also qualitatively modify brain pathology. Here, we compare the pathogenicity of human Abeta42 mutants with differing tendencies to aggregate. We examined the aggregation-prone, EOFAD-related Arctic mutation (Abeta42Arc) and an artificial mutation (Abeta42art) that is known to suppress aggregation and toxicity of Abeta42 in vitro. In the Drosophila brain, Abeta42Arc formed more oligomers and deposits than did wild type Abeta42, while Abeta42art formed fewer oligomers and deposits. The severity of locomotor dysfunction and premature death positively correlated with the aggregation tendencies of Abeta peptides. Surprisingly, however, Abeta42art caused earlier onset of memory defects than Abeta42. More remarkably, each Abeta induced qualitatively different pathologies. Abeta42Arc caused greater neuron loss than did Abeta42, while Abeta42art flies showed the strongest neurite degeneration. This pattern of degeneration coincides with the distribution of Thioflavin S-stained Abeta aggregates: Abeta42Arc formed large deposits in the cell body, Abeta42art accumulated preferentially in the neurites, while Abeta42 accumulated in both locations. Our results demonstrate that manipulation of the aggregation propensity of Abeta42 does not simply change the level of toxicity, but can also result in qualitative shifts in the pathology induced in vivo.     

Development and Characterization of a Nonmorphogenetic Cell Line of Wheat (Triticum aestivum)

This study was conducted to compare characteristics of a wheat (Triticum aestivum L.) cell line to those of the maize (Zea mays L.) black Mexican sweet (BMS) cell line and to compare protoplasts isolated from suspension cells of these cell lines. The wheat cell line was established from immature-embryo derived callus of the experimental line ‘ND7532’ and was conditioned for growth in suspension culture. For both cell lines, measurements of packed cell volume (PCV), fresh weight (FW), and dry weight (DW) were taken at 3 day intervals from suspension cultures. Measurements of FW of calluses cultured from suspension cells of both cell lines were taken at 6 day intervals. The morphogenetic potential of the wheat ND7532 cell line was tested in both callus and suspension cultures using media promoting regeneration and/or organogenesis. Growth rates of ND7532 cells in suspension culture were comparable to those of BMS cells. However, relative growth rates of calluses recovered from ND7532 suspension cells were slower than those of calluses recovered from BMS suspension cells. The ND7532 cell line has very limited morphogenetic potential and has been maintained as rapidly growing callus tissue for 11 years. Yields of protoplasts from suspension cells of the two cell lines were comparable, though ND7532 protoplasts were typically smaller. The wheat cell line has is now designated ND7532-NM (nonmorphogenetic) and is available for cellular and molecular biology research.     

Tpx-1 is a component of the outer dense fibers and acrosome of rat spermatozoa

Previously we reported the cloning of a member of the cysteine-rich secretory protein family, tpx-1, from a testis expression library using an outer dense fiber (ODF)-specific antiserum. Using immunohistochemical and immunoelectron microscopic techniques and Western blotting of purified sperm tail components, we have determined that tpx-1 exists as 25 and 27 kDa proteins in two components of rat spermatid: the ODFs and the acrosome. Tpx-1 mRNA is first expressed in the late pachytene spermatocytes, but the production of these tpx-1 proteins is translationally delayed for 4-5 days before being incorporated into the developing sperm acrosome, surrounding the elongating and condensing spermatid nucleus. Concurrent with sperm head formation, tpx-1 protein was incorporated into the developing sperm tail, and specifically the ODFs. The tpx-1 protein was seen within structures resembling granulated bodies in the cytoplasmic lobe of elongating spermatids and was incorporated subsequently into the growing tail in a manner consistent with ODF development. In addition, tpx-1 protein was localized at the ultrastructural level of the connecting piece of the neck and longitudinal columns of the fibrous sheath, suggesting common protein components in these cytoskeletal structures. As such, tpx-1 may have functional significance in the processes of sperm head development and tail function.     

Maternal regulation of milk composition,milk production,and pouch young development during lactation in the tammar wallaby (Macropus eugenii )

Specific changes in milk composition during lactation in the tammar wallaby (Macropus eugenii) were correlated with the ages of the developing pouch young (PY). The present experiment was designed to test the hypothesis that the sucking pattern of the PY determines the course of mammary development in the tammar wallaby. To test this hypothesis, groups of 60-day-old PY were fostered repeatedly onto one group of host mothers so that a constant sucking stimulus on the mammary gland was maintained for 56 days to allow the lactational stage to progress 42 days ahead of the age of the young. Analysis of the milk in fostered and control groups showed the timing of changes in the concentration of protein and carbohydrate were essentially unaffected by altering the sucking regime. The only change in milk protein secretion was a small delay in the timing of down-regulation of the secretion of whey acidic protein and early lactation protein in the host tammars. In addition, the rates of growth and development of the foster PY were significantly increased relative to those of the control PY because of ingesting more milk with a higher energy content and different composition than normal for their age. The present study demonstrates that the lactating tammar wallaby regulates both milk composition and the rate of milk production and that these determine the rates of PY growth and development, irrespective of the age of the PY.     

Thermodynamic assessment of the stability of thrombin receptor antagonistic peptides in hydrophobic environments

In this paper, a general procedure is described to determine thermodynamic parameters associated with the interaction of thrombin receptor antagonistic peptides (TRAPs) with immobilized nonpolar ligands. The results show that these interactions were associated with nonlinear van't Hoff dependencies over a wide temperature range. Moreover, changes in relevant thermodynamic parameters, namely the changes in Gibbs free energy of interaction, DeltaG(0)assoc, enthalpy of interaction, DeltaH(0)assoc, entropy of interaction, DeltaS(0)assoc, and heat capacity, DeltaC(0)p, have been related to the structural properties of these TRAP analogs. The implications of these investigations for the design of thrombin receptor agonists/antagonists with structures stabilized by intramolecular hydrophobic interactions are discussed.     

Infant vocalization, adult aggression, and fear behavior of an oxytocin null mutant mouse

Previous studies have shown that oxytocin (OT)-deficient female mice produced by homologous recombination fail to lactate but exhibit normal parturition and reproductive behaviors. We examined the ultrasonic vocalizations of infant mice and the subsequent aggressive and fear behavior of adult male OT knockout (OT-KO) mice. Infant OT-KO mice were less vocal than wild-type (WT) control mice during separations from the mother and peers. Adult OT-KO males were generally more aggressive in isolation-induced and resident-intruder tests of aggression and less fearful in the plus maze and acoustic startle reflex tests than WT controls. Although the increase in tests of aggression was robust for OT-KO males from obligate litters (progeny of homozygous x homozygous crossings), the increase in aggression was reduced during tests for OT-KO males derived from nonobligate mating (progeny of heterozygous x heterozygous crossings), suggesting that the OT-KO genotype was not, by itself, responsible for the changes in adult behavior. We conclude that the absence of exposure to OT during development was associated with abnormalities in the development of emotional behavior.     

Isolation of thecal cells: an assessment of purity and steroidogenic potential

In the present investigation, the responsiveness of rat thecal cells, prepared by means of an optimised discontinuous Percoll density gradient centrifugation procedure and cultured under serum-free cell culture conditions, to different concentrations of follitropin (FSH), basic fibroblast growth factor (FGF-2 or bFGF), and lutropin (LH) has been examined. The estradiol (E(2)) and progesterone (P(4)) contents of the cell culture medium were simultaneously determined with aliquots collected after different times of exposure to these regulatory proteins, either individually or in combination. The results confirm that no E(2) could be detected in the cell culture medium of the rat thecal cells prepared and cultured in this manner following all of these different treatments, and hence no contamination of the thecal cell preparations by granulosa cells was evident. The effects of FGF-2 and LH on the steroidogenic and cytodifferentiational properties of these rat thecal cells under serum-free cell culture procedures were also examined. The production of P(4) in the Percoll-purified rat thecal cell cultures receiving different treatments of FSH, and/or FGF-2 did not differ from the basal cell cultures, and no E(2) was detected from the same culture media. In contrast, LH (20 or 50 ng/ml) was found to enhance the production of P(4) (P<0.05) in the serum-free cell culture media. The stimulation of P(4) production was greater at higher LH concentration (50 ng/ml) (P<0.05). Concurrent treatment of LH (20 or 50 ng/ml) and FGF-2 (1-100 ng/ml) showed that FGF-2 inhibited the production of P(4) by LH-stimulated thecal cell cultures (P<0.05). The inhibition by FGF-2 was greater when LH was at a lower concentration (EC(50)<1 ng/ml at LH-20 ng/ml vs. EC(50)>1 ng/ml at LH-50 ng/ml). The results of the present study thus indicate that rat thecal cells isolated by this optimised Percoll density centrifugation procedure maintain a very high steroidogenic potential and specificity. Consistent with the absence of contaminating granulosa cells, these rat theca cell preparations do not respond to FSH treatment in terms of E(2) production. However, these rat theca cell preparations can be stimulated by LH to express their differentiated status in serum-free medium and respond to growth factors such as FGF-2.     

Presence of novel N-CAM glycoforms in the rat olfactory system

The functional activity of the neural cell adhesion molecule N-CAM can be modulated by posttranslational modifications such as glycosylation. For instance, the long polysialic acid side chains of N-CAM alter the adhesion properties of the protein backbone. In the present study, we identified two novel carbohydrates present on N-CAM, NOC-3 and NOC-4. Both carbohydrates were detected on N-CAM glycoforms expressed by subpopulations of primary sensory olfactory neurons in the rat olfactory system. Based on the expression of NOC-3 and NOC-4 and the olfactory marker protein (OMP), four independent subpopulations of primary sensory olfactory neurons were characterized. These neurons expressed: both NOC-3 and NOC-4 but not OMP; both NOC-4 and OMP but not NOC-3; NOC-3, NOC-4, and OMP together; and OMP alone. The NOC-3- and NOC-4-expressing neurons were widely dispersed in the olfactory neuroepithelium lining the nasal cavity. The axons of NOC-4 expressing neurons innervated all glomeruli in the olfactory bulb, whereas the NOC-3 expressing axons terminated in a discrete subset of glomeruli scattered throughout the whole olfactory bulb. We propose that both NOC-3 and NOC-4 are part of a chemical code of olfactory neurons which is used in establishing the topography of connections between the olfactory neuroepithelium and the olfactory bulb. © 1997 John Wiley & Sons, Inc. J Neurobiol 32 : 659–670, 1997