Haploid phase

It is presumably the ability to survive as a heterozygote, even with one or more highly deleterious mutations, that has led to the dominance of the diploid phase in higher plants and animals.76 However, to the biochemical geneticist organisms with a haploid phase offer experimental advantages because recessive mutants can be detected readily. 

HETEROTHALLIC Having two or more genetically incompatible but morphologically similar haploid phases which function as separate sexes or strains (as in some algae and fungi). 

Many details are still obscure, and data are only available from a limited number of species, but it appears that most coccolithophores alternate between fully armored (heterococcolith-covered) diploid life stages and less-well-armoured (either holococcolith-covered or else naked) haploid phases. Both phases are capable of indefinite asexual reproduction, which is rather unusual among protists. That sexual reproduction also occurs fairly frequently is evidenced by the observation of significant genetic diversity within coccolithophore blooms. Bloom populations do not consist of just one clone... 

Applications of In Vitro Selection Systems Whole-Plant Selection Using the Haploid Phase of Ceratopteris... 

Protamines are small nuclear proteins that replace histones in the haploid phase of spermatogenesis. Because they are arginine-rich proteins they are positively charged at physiological pH, being able to interact with DNA to enable its condensation and stabilization. Protamine can be used in the form of the sulfate or free base, two different forms that may significantly influence the physicochemical properties of the nanoparticles, especially their size [ 116], the sulfate salt being the most used form of the polymer. 

Valero M, Richerd S, Perrot V, Destombe C (1992) Evolution of alternation of haploid and diploid phases in life cycles. Trends Ecol Evol 7 25-29... 

The existence of different morphotypes, two ploidy levels related to phase changes, and the ability of both haploid and diploid stages to divide mitotically (Kornmann 1955 Rousseau et al. 1994 Vaulot et al. 1994), support the existence of a haploid-diploid life cycle in P. globosa. In such life cycles, both haploid and diploid stages are related by sexual processes, meiosis and syngamy, and both are capable of mitotic division (Fig. 3 ... 

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