Learning of olfactory cues is not necessary for early lamb recognition by the mother

Ewes identify their young through the use of different sensory modalities. Olfactory recognition, which mediates selective acceptance at the udder, is established at 4 h postpartum (pp). Visual and auditory cues are involved in recognition at a distance, which is evident at 12 h pp. This study investigates whether anosmic ewes are able (a) to develop visual and auditory recognition and (b) to restore selective acceptance of their lamb at the udder. Visual and auditory recognition was assessed in anosmic and intact ewes at 12 h and 24 h pp by a test of two choices: their own and an alien lamb. Selectivity at allowing suckling was tested by presenting successively an alien and the familiar lamb at 4 h, 3 days, and 1 month pp. In the two-choice recognition test, at both 12 h and 24 h pp, anosmic as well as intact ewes showed a preference for their familiar lamb. Although anosmic ewes showed no difference in their acceptance of alien and familiar lambs for suckling at 4 h and 3 days pp, they nursed the alien lamb less at 1 month pp and showed more rejection behaviors toward it. Thus, visual, auditory, or both those types of recognition can be rapidly established, independent of olfactory recognition. Moreover, differential behavior of anosmic ewes toward their own versus an alien lamb at the udder at 1 month suggests that vision and audition may compensate to some extent for the loss of olfaction.     

Functional consequences of ROMK mutants linked to antenatal Bartter's syndrome and implications for treatment

The antenatal variant of Bartter's syndrome is an autosomal recessive kidney disease characterized by polyhydramnios, premature delivery, hypokalemic alkalosis and hypercalciuria. It is genetically heterogeneous, having been linked recently to mutations in an ATP- sensitive, renal outer medullary K+channel, ROMK, and earlier to mutations in the Na-K-2Cl co-transporter, NKCC2. We characterized four of the mutations reported in three heterozygous ROMK variants of antenatal Bartter's and found that each expressed a distinct phenotype in Sf9 cells. One mutation expressed normal function and appears to be an allelic polymorphism. The other three mutations produced channels with significantly reduced K+fluxes. However, the mechanisms in each case were different and reflected abnormalities in phosphorylation, proteolytic processing or protein trafficking. The different mechanisms may be important in the design of appropriate therapy for patients with this disease.      

Uterine myomata and outcome of assisted reproduction

The aim of this work was to study the effect of uterine myomata on the implantation rate and outcome in in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). Among 406 patients, 51 (12.6%) were found to have uterine corporeal myomata. Twelve patients were excluded from the study as they had large myomata, submucous myomata or intramural myomata encroaching on the cavity. These patients were advised to have myomectomy before being enrolled in the IVF/ICSI programme. The remaining patients (n = 39) were sorted according to the number, site and size of the myomata as assessed by transvaginal sonography. Three patients had more than one myoma. Most of the myomata were subserous (72.7%) and the mean diameter of the myomata was 3.5 +/- 0.9 cm. A control group (n = 367) was chosen with normal uteri and no history of uterine reconstruction surgery. The mean age of myoma patients was 34.7 +/- 3.6 years as compared to 34.0 +/- 4.4 years in the control group. The age, period of infertility, body mass index, duration and number of human menopausal gonadotrophin ampoules needed for stimulation, oestradiol levels, number of oocytes retrieved and the fertilization rate were not significantly different in the myoma patients compared to the control group. Fifteen myoma patients (38.5%) subsequently showed one or more pregnancy sacs on ultrasonography of which three (20%) spontaneously aborted during the first trimester and two (13.3%) had preterm labour, as compared to 123 (33.5%), 19 (15.5%) and nine (7.3%) respectively, among the control group (P = 0.27, 0.33 and 0.21). In conclusion, uterine corporeal myomata, not encroaching on the cavity and <7 cm in mean diameter, do not affect the implantation or miscarriage rates in IVF or ICSI.      

Germline mutations of the CDKN2 gene in UK melanoma families

Germline mutations in CDKN2 on chromosome 9p21, which codes for the cyclin D kinase inhibitor p16, and more rarely, mutations in the gene coding for CDK4, the protein to which p16 binds, underlie susceptibility in some melanoma families. We have sequenced all exons of CDKN2 and analysed the CDK4 gene for mutations in 27 UK families showing evidence of predisposition to melanoma. Five different germline mutations in CDKN2 were found in six families. Three of the mutations (Met53Ile, Arg24Pro and 23ins24) have been reported previously. We have identified two novel CDKN2 mutations (88delG and Ala118Thr) which are likely to be associated with the development of melanoma, because of their co-segregation with the disease and their likely functional effect on the CDKN2 protein. In binding assays the protein expressed from the previously described mutation, Met53Ile, did not bind to CDK4/CDK6, confirming its role as a causal mutation in the development of melanoma. Ala118Thr appeared to be functional in this assay. Arg24Pro appeared to bind to CDK6, but not to CDK4. No mutations were detected in exon 2 of CDK4, suggesting that causal mutations in this gene are uncommon. The penetrance of these mutant CDKN2 genes is not yet established, nor is the risk of non-melanoma cancer to gene carriers.      

Determination of the parent of origin in nine cases of prenatally detected chromosome aberrations found after intracytoplasmic sperm injection

Prenatal cytogenetic analysis of 71 fetuses conceived by intracytoplasmic sperm injection (ICSI) resulted in the detection of nine (12.7%) chromosome aberrations including two cases of 47,XXY, four cases involving a 45,X cell line and three autosomal trisomies. Molecular analysis of the parental origin of the deleted or supernumerary chromosome was performed by using polymorphic microsatellite markers. Six cases involving a sex chromosome abnormality were found to be of paternal origin while the two trisomic cases that could be analysed were of maternal origin. Two cases involved the same infertile couple who had two consecutive ICSI pregnancies terminated because of a chromosome abnormality. The replaced embryos in both cases originated from a single batch of ICSI fertilized oocytes of which part was used to initiate the first pregnancy and part was cryopreserved and used to initiate the second pregnancy.