Karyolysus
Encyclopedia
Karyolysus is a genus of coccidia. With the exception of K. sonomae whose vertebrate host is the yellow legged frog (Rana boyli boyli) species in this genus only infect lizards of the genus Lacerta
.
The family Karyolysidae was created by Wenyon in 1926.
The type speces is Karyolysus lacertae
.
Gametogony occurs in the erythrocytes after their penetration by the merozoites.
Differentiation from the genus Haemogregarina
may be difficult as in both genera gametocytogenis occurs in the erythrocytes and are have similar morphology. They can be distinguished on the location of schizogony: In Karyolysus this occurs in the endothelial cells of the visera while in Haemogregarina schizogony occurs in the bone marrow
.
s which the host lizard
ingests the veriform sporozoites are released from the sporocyst
s. These newly liberated sporozoites bore into the intestinal wall and enter the lymph
atic vessels and the blood
stream. On reaching the vsiera and in particular the liver
the sporozoites penetrate the endothelial cells. There they form ovoid schizonts within a membranous capsule. They remain in these cells for some time and give rise to 8 to 30 merozoites. The merozoites remain in the cell for some time before rupturing it and entering the blood stream.
On entering the blood stream the merozoites penetrate other endothelial cells. There they grow and undergo schizogeny producing a number of small merozoites. These second generation schizonts are smaller than the first generation and lack a discerable nucleous. These are also eventually released into the blood stream, This occurs usually day 42 post infection.
These small merozoites are actually gametocyte
s. These penetrate erythrocytes and differentiate into macrogametoctyes and microgametocytes. Both types are surrounded by a thin membrane. The microgametocytes remain thin and do not develop a nucleous. The macrogametocytes in contrast enlarge and develop a visible nucleous at one end of the nucleus.
On ingestion by a female mite (male mites do not require blood) the gametocytes are released from the erythrocytes. Within the gut they associate in spindle like pairs and enter the epithelial cells of the gut. Within the epithelial cell the macrogametocyte increases in size while the microgametocyte shrinks. The microgametocyte divides in two and one of the motile gametes so formed fuses with the macrogametocyte to form a zygote
.
The zygote (or ookinete) grows within the cell and undergoes meiosis
followed by several rounds of mitosis
. The ookinte is now known as an oocyst. Within the oocyst the nuclei migrate to the surface of the oocyst and gather cytoplasm around them becoming known as sporoblasts. As they mature become vermicular in shape and are known as sporokinetes. These which are very active.
On release from the oocyst the sporokinetes migrate throughout the body of the mite. Some settle in the ovaries and enter the yolk of the egg
s. Within the egg they develop a membrane and grow within this. This stage is known as the sporocyst. Within the sporocyst sporogony generates 20 to 30 sporozoites. These invade the developing nymph and enter the endodermal cells of the gut. On feeding some of the sporozoites enter the gut. Some remain within the gut while others exit in the faeces. When a lizard swallows the faeces or the mite which may be feeding on it the cycle begins again.
Hypnozoites are found in Karyolysus lacerate.
Lacerta
Lacerta is one of the 88 modern constellations defined by the International Astronomical Union. Its name is Latin for lizard. A small, faint constellation, it was created in 1687 by the astronomer Johannes Hevelius. Its brightest stars form a "W" shape similar to that of Cassiopeia, and it is thus...
.
History
The genus was created by Labbe in 1894 for those species of sporozoans that fragmented the host nucleus. Reichenow in 1921 established that this property was of dubious taxonomic value. He propose a different set of criteria for inclusion in this genus and these are the one currently in use.The family Karyolysidae was created by Wenyon in 1926.
The type speces is Karyolysus lacertae
.
Characteristics of the genus
Schizongeny occurs in the endothelial cellsGametogony occurs in the erythrocytes after their penetration by the merozoites.
Differentiation from the genus Haemogregarina
Haemogregarina
Haemogregarina is a genus of haemoprotozoans, parasitic mainly on cold-blooded vertebrates. They are unicellular organisms which are parasitic in the red blood cells.-History:...
may be difficult as in both genera gametocytogenis occurs in the erythrocytes and are have similar morphology. They can be distinguished on the location of schizogony: In Karyolysus this occurs in the endothelial cells of the visera while in Haemogregarina schizogony occurs in the bone marrow
Bone marrow
Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...
.
Life cycle
Starting with infected miteMite
Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...
s which the host lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
ingests the veriform sporozoites are released from the sporocyst
Sporocyst
Sporocyst is a common name of a lifecycle stage in two unrelated groups of species:*Apicomplexa parasites: see Apicomplexa lifecycle stages*Trematode flatworms: see Trematode lifecycle stages...
s. These newly liberated sporozoites bore into the intestinal wall and enter the lymph
Lymph
Lymph is considered a part of the interstitial fluid, the fluid which lies in the interstices of all body tissues. Interstitial fluid becomes lymph when it enters a lymph capillary...
atic vessels and the blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
stream. On reaching the vsiera and in particular the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
the sporozoites penetrate the endothelial cells. There they form ovoid schizonts within a membranous capsule. They remain in these cells for some time and give rise to 8 to 30 merozoites. The merozoites remain in the cell for some time before rupturing it and entering the blood stream.
On entering the blood stream the merozoites penetrate other endothelial cells. There they grow and undergo schizogeny producing a number of small merozoites. These second generation schizonts are smaller than the first generation and lack a discerable nucleous. These are also eventually released into the blood stream, This occurs usually day 42 post infection.
These small merozoites are actually gametocyte
Gametocyte
A gametocyte is a eukaryotic germ cell that divides by mitosis into other gametocytes or by meiosis into gametids during gametogenesis. Male gametocytes are called spermatocytes, and female gametocytes are called oocytes....
s. These penetrate erythrocytes and differentiate into macrogametoctyes and microgametocytes. Both types are surrounded by a thin membrane. The microgametocytes remain thin and do not develop a nucleous. The macrogametocytes in contrast enlarge and develop a visible nucleous at one end of the nucleus.
On ingestion by a female mite (male mites do not require blood) the gametocytes are released from the erythrocytes. Within the gut they associate in spindle like pairs and enter the epithelial cells of the gut. Within the epithelial cell the macrogametocyte increases in size while the microgametocyte shrinks. The microgametocyte divides in two and one of the motile gametes so formed fuses with the macrogametocyte to form a zygote
Zygote
A zygote , or zygocyte, is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo...
.
The zygote (or ookinete) grows within the cell and undergoes meiosis
Meiosis
Meiosis is a special type of cell division necessary for sexual reproduction. The cells produced by meiosis are gametes or spores. The animals' gametes are called sperm and egg cells....
followed by several rounds of mitosis
Mitosis
Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly...
. The ookinte is now known as an oocyst. Within the oocyst the nuclei migrate to the surface of the oocyst and gather cytoplasm around them becoming known as sporoblasts. As they mature become vermicular in shape and are known as sporokinetes. These which are very active.
On release from the oocyst the sporokinetes migrate throughout the body of the mite. Some settle in the ovaries and enter the yolk of the egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s. Within the egg they develop a membrane and grow within this. This stage is known as the sporocyst. Within the sporocyst sporogony generates 20 to 30 sporozoites. These invade the developing nymph and enter the endodermal cells of the gut. On feeding some of the sporozoites enter the gut. Some remain within the gut while others exit in the faeces. When a lizard swallows the faeces or the mite which may be feeding on it the cycle begins again.
Hypnozoites are found in Karyolysus lacerate.