Tanzania's vanishing rain forests — assessment of nature conservation values, biodiversity and importance for water catchment

The rain forests of Tanzania occupy small areas, mostly confined to isolated mountains. Except for some isolated volcanic mountains (Mt. Kilimanjaro, Mt. Meru, the Ngorongoro Crater), most of the rain forests are confined to the so-called Eastern Arc mountains with old crystalline bedrocks. The Eastern Arc rain forests are characterized by high biodiversity, and have large numbers of endemic and rare taxa of plants and animals. The submontane and montane rain forests are extremely important water catchments, providing water for major cities and densely populated rural areas. Most of the rain forest catchments are forest reserves, but still the human impact around and inside the reserves is considerable. Intensive cultivation due to heavy population pressure affects the reserves from all sides, leaving the forests isolated, fragmented ‘islands’ surrounded by the cultural landscape. Former timber production and logging programs initiated by the State and some foreign development organizations have depleted large areas of rain forests, e.g. in the Usambara Mountains. Extensive, destructive, legal and illegal activities such as, e.g. logging, pit-sawing and grazing have taken place inside most of the forest reserves. Some research programs on rain forest catchments are now being carried out in Tanzania, forming a basis for future management and monitoring of the forest reserves. The forest authorities are currently much concerned about the problems, giving catchment forest management highest priority in the Tropical Forestry Action Plan.     

Mosaicism of isochromosome 18p.

The first case of isochromosome 18p as a mosaic in a male fetus diagnosed by amniocentesis is reported. After termination of the pregnancy at 21 weeks gestation biopsies from different fetal organs as well as from the placenta were taken and set up for long term cell cultures. The distribution of the normal and abnormal cell-line in fetal organs was unequal. Unexpectedly the metaphases in the placenta and the lymphocyte culture all showed a normal karyotype. The tetrasomy 18p is associated with a uniform phenotype, even in fetal life, characterized by a small head with protuberant occiput, low-set ears with posterior rotation, epicanthic fold, sharp pinched nose, convex and poorly formed philtrum, high-arched palate, retrognathia, flexion contractures of fingers, short and broad hallux, hypoplastic penis, angulation of clavicles and mild scoliosis. The propositus showed no growth retardation.     

Human Settlements on the Northern Shores of Lake Aral and Water Level Changes

The shore of Lake Aral in Kazakhstan is a perfect area for studying the human adaptation strategy to past climate changes. New archaeological material, gathered along the northern shores during the expedition of the INTAS project CLIMAN, is briefly presented. Changes in settlement activity during the Atlantic and Subboreal are related to lake level changes of the Aral Sea. A previ-ously proposed lake level maximum needs to be revised. In particular the lake level stand at 72/73 m, with an assumed age of 5000 BP is definitely refused. Based on the presented data the maximum lake level most probably never reached beyond 57/58 mean average sea level (masl). Furthermore the regression during the 15^th–16^th centuries has been underestimated. It may have been lower than the present day level. Thus the present desiccation of the Aral Sea is historically not unique, as a similar regression, probably induced by man as well, has occurred at least once during history. A readjustment of the water level is, therefore, possible at any time.     

Prenatal diagnosis of aortic atresia by colour doppler flow mapping

A case of aortic atresia with insufficiency of mitral valve diagnosed prenatally at 33 weeks of gestation is presented. An accurate diagnosis of this fetal cardiovascular malformation was possible by application of Doppler colour flow mapping, which demonstrated (a) the absence of forward flow in the hypoplastic ascending aorta, (b) reverse flow of blood from the ductus arteriosus into the severely hypoplastic ascending aorta in the late systole, (c) pansystolic mitral valve regurgitation, and (d) absent flow across the foramen ovale as a result of premature closure of the foramen ovale.     

HLA-A,B,C,DR typing and 17-OHP determination for second trimester prenatal diagnosis of 21-hydroxylase deficient CAH

In 18 families at risk for the HLA-linked, 21-hydroxylase deficient form of autosomal recessive congenital adrenal hyperplasia (CAH), prenatal diagnosis (PD) was performed using two methods: (1) HLA-A,B,C typing and in the latter 11 cases also DR typing of cultured amniotic fluid cells (AFC) using the standard microcytotoxicity assay, and (2) measurement of second trimester amniotic fluid 17-hydroxyprogesterone (17-OHP) concentration using gel chromatography and radioimmunoassay. The accuracy of the prenatal predictions was confirmed by postnatal HLA typing of umbilical cord blood lymphocytes and by clinical evaluation. In 16/18 families, both HLA typing of AFC and 17-OHP measurements proved informative for PD. The predictions of both methods were concordant in 14/16 families (88 per cent). In ten of these families, a normal fetus was predicted, and in four, an affected fetus; all pregnancies were carried to term and all predictions were confirmed postnatally. In 2/16 cases (12 per cent), however, the predictions were discordant: the prenatal HLA typing indicated an affected fetus, whereas the 17-OHP values predicted a normal fetus. Both pregnancies were continued and two healthy boys were delivered. The discordance proved to be due to a ‘missed’ HLA antigen in one case and to serologically cross-reactive HLA antigens in the second. Finally, in 2/18 cases, prenatal assessment of fetal genotype had to rely on HLA typing alone as 17-OHP measurement was not performed in one family and in the second family the 17-OHP values obtained were not informative due to inadvertent continuation of hormone therapy to the date of amniocentesis. In both cases, the HLA typing data accurately predicted a normal fetus. In conclusion, a combination of HLA typing of cultured AFC and 17-OHP measurements of amniotic fluid permits accurate prenatal diagnosis of CAH in most cases (88 per cent). In addition, the supplementary use of HLA-DR typing of AFC as presented here for the first time proved helpful in families with HLA-A.B homozygosity due to parental sharing of antigens and can be informative for identifying HLA-B/21-OH recombinant haplotypes.