Limits...
Size isn't everything.

Ellis RE, Wei Q - Elife (2015)

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, United States ellisre@rowan.edu.

ABSTRACT

Male nematode worms may make larger sperm than hermaphrodite worms, but this is not the only reason that sperm from males have a competitive edge.

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Related in: MedlinePlus

COMP-1 controls sperm competition in nematodes.(A) When a normal male (outlined in blue) mates with a hermaphrodite (red), his sperm (blue) are larger than the hermaphrodite sperm (pink) and are better able to compete for positions in the two spermathecae (purple). Sperm located in the spermathecae are in a better position to fertilize the hermaphrodite's oocytes. Some sperm and a young embryo are shown in the uterus (brown), and the passage of an oocyte through the spermatheca on the right has dislodged the sperm. The region inside the dashed box is expanded in B–D. (B) Male sperm can normally outcompete hermaphrodite sperm and enter the spermathecae (middle), but Hansen et al. show that comp-1 mutant male sperm (green) are outcompeted by hermaphrodite sperm (bottom). (C) Furthermore, although comp-1 sperm can fertilize female oocytes in the absence of competition (bottom), they cannot compete with normal male sperm (middle). (D) When both the male sperm (green) and hermaphrodite sperm (orange) are made by comp-1 mutants, the larger male sperm have a competitive advantage. This shows that the COMP-1 protein and sperm size independently affect competition.
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fig1: COMP-1 controls sperm competition in nematodes.(A) When a normal male (outlined in blue) mates with a hermaphrodite (red), his sperm (blue) are larger than the hermaphrodite sperm (pink) and are better able to compete for positions in the two spermathecae (purple). Sperm located in the spermathecae are in a better position to fertilize the hermaphrodite's oocytes. Some sperm and a young embryo are shown in the uterus (brown), and the passage of an oocyte through the spermatheca on the right has dislodged the sperm. The region inside the dashed box is expanded in B–D. (B) Male sperm can normally outcompete hermaphrodite sperm and enter the spermathecae (middle), but Hansen et al. show that comp-1 mutant male sperm (green) are outcompeted by hermaphrodite sperm (bottom). (C) Furthermore, although comp-1 sperm can fertilize female oocytes in the absence of competition (bottom), they cannot compete with normal male sperm (middle). (D) When both the male sperm (green) and hermaphrodite sperm (orange) are made by comp-1 mutants, the larger male sperm have a competitive advantage. This shows that the COMP-1 protein and sperm size independently affect competition.

Mentions: As a result, a simple model for how nematode sperm compete was proposed (Figure 1A; Ellis and Scharer, 2014). Inside a hermaphrodite, sperm are stored in the two structures called spermathecae and fight for positions near the maturing oocytes, where they will have the best chance of fertilization. Since each newly fertilized oocyte passes through the spermatheca, it dislodges many of the sperm, setting up a new round of competition to move into a good spot. Larger sperm appear to handle this intense competition better.Figure 1.COMP-1 controls sperm competition in nematodes.


Size isn't everything.

Ellis RE, Wei Q - Elife (2015)

COMP-1 controls sperm competition in nematodes.(A) When a normal male (outlined in blue) mates with a hermaphrodite (red), his sperm (blue) are larger than the hermaphrodite sperm (pink) and are better able to compete for positions in the two spermathecae (purple). Sperm located in the spermathecae are in a better position to fertilize the hermaphrodite's oocytes. Some sperm and a young embryo are shown in the uterus (brown), and the passage of an oocyte through the spermatheca on the right has dislodged the sperm. The region inside the dashed box is expanded in B–D. (B) Male sperm can normally outcompete hermaphrodite sperm and enter the spermathecae (middle), but Hansen et al. show that comp-1 mutant male sperm (green) are outcompeted by hermaphrodite sperm (bottom). (C) Furthermore, although comp-1 sperm can fertilize female oocytes in the absence of competition (bottom), they cannot compete with normal male sperm (middle). (D) When both the male sperm (green) and hermaphrodite sperm (orange) are made by comp-1 mutants, the larger male sperm have a competitive advantage. This shows that the COMP-1 protein and sperm size independently affect competition.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4400580&req=5

fig1: COMP-1 controls sperm competition in nematodes.(A) When a normal male (outlined in blue) mates with a hermaphrodite (red), his sperm (blue) are larger than the hermaphrodite sperm (pink) and are better able to compete for positions in the two spermathecae (purple). Sperm located in the spermathecae are in a better position to fertilize the hermaphrodite's oocytes. Some sperm and a young embryo are shown in the uterus (brown), and the passage of an oocyte through the spermatheca on the right has dislodged the sperm. The region inside the dashed box is expanded in B–D. (B) Male sperm can normally outcompete hermaphrodite sperm and enter the spermathecae (middle), but Hansen et al. show that comp-1 mutant male sperm (green) are outcompeted by hermaphrodite sperm (bottom). (C) Furthermore, although comp-1 sperm can fertilize female oocytes in the absence of competition (bottom), they cannot compete with normal male sperm (middle). (D) When both the male sperm (green) and hermaphrodite sperm (orange) are made by comp-1 mutants, the larger male sperm have a competitive advantage. This shows that the COMP-1 protein and sperm size independently affect competition.
Mentions: As a result, a simple model for how nematode sperm compete was proposed (Figure 1A; Ellis and Scharer, 2014). Inside a hermaphrodite, sperm are stored in the two structures called spermathecae and fight for positions near the maturing oocytes, where they will have the best chance of fertilization. Since each newly fertilized oocyte passes through the spermatheca, it dislodges many of the sperm, setting up a new round of competition to move into a good spot. Larger sperm appear to handle this intense competition better.Figure 1.COMP-1 controls sperm competition in nematodes.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, United States ellisre@rowan.edu.

ABSTRACT

Male nematode worms may make larger sperm than hermaphrodite worms, but this is not the only reason that sperm from males have a competitive edge.

Show MeSH
Related in: MedlinePlus