Occurrence Of Intersex Research Articles

Intersexes in Mississippi River shovelnose sturgeon sampled below Saint Louis, Missouri, USA

The Missouri Department of Conservation detected high organochlorine levels in tissues of fish from the Mississippi River south of Saint Louis. Chlordane, which is both a carcinogen and an endocrine disrupter, reached 2960 μg/kg in fillets of shovelnose sturgeon, Scaphirhynchus platyorynchus, and 1926 μg/kg in their roe, wet weight basis. Polychlorinated biphenyls (PCBs) and p,p′-dichlorodiphenyldichloroethylene (DDE) in roe have reached 5810 and 780 μg/kg, respectively. The purpose of this study was to determine if endocrine disrupters and carcinogens are a potential cause of the significantly diminished reproduction capacity and population declines in the endangered pallid sturgeon, Scaphirhynchus albus. Twenty-four surrogate shovelnose sturgeons were sampled north of Saint Louis where contaminant levels were lower compared with 17 sampled south of Saint Louis where contaminant levels were high. Liver and gonad tissues were formalin-fixed, histologically processed and examined. Neoplasms were not found. The principal finding was that the testes of two of the seven downstream male fish contained ovigerous lamellae, in addition to mature sperm. Since sturgeons are gonochoristic and intersexes are rare and unusual, the occurrence of intersex in 29% of the male Mississippi River shovelnose sturgeon examined from a population contaminated with chlordane and other chemicals raise concern for human health, species biodiversity and preservation of waterway quality. These findings, however, need to be corroborated by expanded studies with a higher sample size.

Is intersexuality a cost of environmental sex determination in Gammarus duebeni?

Three possible causes of intersexuality in Gammarus duebeni, a crustacean with environmental sex determination, were investigated. Intersexuality appears to be a cost of the flexible sex‐determining mechanism of this species: the occurrence of intersexes is influenced by photoperiod, which also cues sex determination. Intersexuality is heritable: intersex mothers produce more intersex offspring than do true females. Parasitism by a feminizing microsporidian is ruled out as a significant cause of intersexuality.

The occurrence of intersexuality in harpacticoid copepods and its relationship with pollution

Intersexuality in harpacticoid copepods is extremely rare, only one specimen having previously been recorded in the literature over 40 years ago. We record the presence of intersexes of several species in the Firth of Forth and elsewhere in Scotland. The possibility that pollution may be implicated in the causation of the phenomenon is suggested by the high level of intersexuality in the vicinity of a major sewage discharge off Edinburgh, where 93% of the specimens examined of one of the dominant species exhibit intersexuality.

Resistance in coffee to Meloidogyne spp. and occurrence of intersexes in M. thamesi

Resistance in coffee to Meloidogyne spp. and occurrence of intersexes in M. thamesi

THE FREQUENCY OF OCCURRENCE OF INTERSEXES IN MILK GOATS

1) In the male which is homozygous for the intersexual gene, no abnormalities appear in its sexuality, and accordingly such males occasionally used as sires.2) As most of the sires were heterozygous for the intersexual gene in Japan, so the percentage of intersexes would be on the increase and will approach to 7.3% of occurrence in the near future. With the increase of intersexes, the homozygous recessive males also will be on the increase. If some homozygous, recessive males were used as sires in the herd, the occurrence of intersexual kids would become 14.6%, and if these were continued to mate in the herd, it would show the highest frequency of occurrence of intersexes, being attained to 25% of the total kids or 50% of the female ones.3) To eliminate the intersexual gene, the proven sire must be used continuously for over seven generations, and when progeny test is difficult to apply, to use the horned male as the sire seems also to be the effective method of breeding.