Curd Coconut: Its Mystery and Potentialities (Review Article)

Curd coconut (CC) is a rare abnormality in the meat of the coconut which is thicker than normal and is fluffy and soft like curd. Being more delicious than normal coconut, CC is favored by people who eat it as dessert. In ten countries where CC occurs, its occurrence is at a very low frequency of about 0.15%. CC is produced on a normal-looking palm which bears mostly normal fruits except for a very few CC fruits. Such fruit does not germinate, thus cannot be used to propagate the character. The experienced growers germinate normal-looking fruits obtained from the CC-bearing palm, which may or may not yield CC fruits after 8 years of planting. A controlled self-pollination of the CC-bearing palm yield a 3:1 ratio of normal: CC fruits, indicating the mother palm is a heterozygote (Kk) for the CC character, which is recessive (kk). The CC endosperm (kkk) cannot produce the enzyme galacto-mannanse to digest galactomannan to produce mannan. Thus, it contains galacto-mannanase that is viscous, but is not digested as food of the CC embryo. Consequently, it eventually dies. Galactomannan is responsible for the fluffy texture of the CC. CC embryo can be cultured in aseptic condition. Upon growing this cultured embryo to fruit-bearing stage, CC fruits are produced 100% if self pollinated. A hybridization scheme has been conducted by the Thailand Horticultural Research Institute. Pollen sources were from embryo-cultured palms while maternal parents were found dwarf cultivars, namely ‘Nam Hom’, ‘Thung Khlet’, Malayan Yellow Dwarf’, and ‘Malayan Red Dwarf’. The F1 hybrids were mostly semi-dwarf in stature (that is selfing in nature); they all produced 25% CC fruits as expected. The most interesting cross was that with ‘Nam Hom’, in which 56% have aromatic water. It is postulated that if a backcross is made between semi-dwarf F1 with the CC homozygous (kk) embryo-cultured palms, the resultant offspring would yield 50% CC fruits which doubled that of the F2 which yield only 25% CC fruits. Not only CC fruits are delicious, they are also nutritious with higher amount of saturated and less unsaturated fatty acid than normal fruits. CC is always high on demand because people love to eat CC as dessert, even at the price ten times as much as ordinary coconut. CC growers earn 2.5 times as much compared to ordinary palms if they grow F1 hybrids, but will double that amount if they make backcross by using pollens from homozygous embryo-cultured palms (kk).

The albino deletion complex and early postimplantation survival in the mouse

The albino deletion complex in the mouse represents 37 overlapping chromosomal deficiencies that have been arranged into at least twelve complementation groups. Many of the deletions cover regions of chromosome 7 that contain genes necessary for early embryonic development. The work reported here concentrates on two of these deletions (c6H, c11DSD), both of which were known to be lethal around the time of gastrulation when homozygous. A detailed embryological analysis has revealed distinct differences in the lethal phenotype associated with the c6H and c11DSD deletions. c6H homozygous embryos are grossly abnormal at day 7.5 of gestation, whereas c11DSD homozygous embryos appear abnormal at day 8.5 of gestation. There is no development of the extraembryonic ectoderm in c6H homozygotes, whereas extensive development of this tissue type occurs in c11DSD homozygotes. The visceral endoderm is abnormally shaped and the parietal endoderm appears to be overproduced in c6H homozygotes; these structures are not affected in c11DSD homozygotes. The embryonic ectoderm is runted in both types of embryo and it is not possible to obtain homozygous embryo-derived stem-cell lines for either deletion. Mesoderm formation occurs in the c11DSD but not in the c6H homozygotes. The c11DSD deletion chromosome complements the c6H chromosome in that the lethal phenotype of the compound heterozygote is similar to that of the c11DSD homozygote. These results suggest that a gene(s) necessary for normal development of the extraembryonic ectoderm is present in the c11DSD but deficient in the c6H deletion chromosome.