title: Gonad examination reveals diandry and baseline DNA methylation in the three sexual phenotypes of the New Zealand spotty wrasse, Notolabrus celidotus

authors: Robertson, Holly A.

subjects: gonad

abstract: Understanding reproductive plasticity and how sexual phenotypes arise is of great interest to biology, particularly the form and function of sex changing fish. However, there are gaps regarding detailed descriptions of gonad morphology and structure of the different sexual phenotypes. Furthermore, the role of epigenetic regulation has yet to be applied to these studies. 
Sexually mature terminal phase (TP) males were significantly larger in length, and weight (214 ± 7.74 mm standard length (SL), 146 ± 16.6 g), than the similar sized sexually mature initial phase (IP) males (169 ± 6.24 mm SL, 67 ± 9.52 g) and sexually mature females (167 ± 3.54 mm SL, 61 ± 4.07 g). There was a large overlap in size distributions with a vast size range in sexually mature males (147 – 240 mm SL, 42 – 221 g) and small sexually mature females (146 – 183 mm, 41 – 82 g). These results suggest small males use female mimicry and overlapping size ranges suggest diandry. 
Three gonad types were identified, one ovary and two types of testis. Solid testes were more common in IP males than in TP males. It is proposed that the unique and complex shape of the solid testis arises through an evagination process in juvenile males. Hollow testes arise through sex change from female and are more common in TP males. Colour phase not always corresponding to testis type suggests the ability to transition between body colour phenotype according to environmental influences, and two testis types suggest two different developmental pathways to become a male (diandry). 
Females and one male were identified as juveniles. All sexually mature males had similar testis lobular structure and somatic and germ cell arrangement. The structural arrangement of the solid testis was consistent with primary male testes, and the hollow testis was consistent with secondary male testes. Juvenile males and the existence of primary and secondary testes are associated with diandry in protogynous species. 
Whole-genome percentage methylation analysis revealed no significant difference in global brain DNA methylation between females (71.4 ± 1.06 %), TP males (72.2 ± 0.5 %) or IP males (75.1 %). Global ovarian methylation (53.7 ± 1.16 %) was significantly lower than both the similarly high global methylation in the IP male testis (82.2 ± 1.39 %) and TP male testis (86.8 ± 0.21 %). Ovaries during spawning season (67.3 ± 1.27 %) had significantly higher global methylation than ovaries outside of spawning season (51.4 ± 0.96 %). Global gonad DNA methylation variations suggest sex-specific differences and seasonal effects on reproduction are under epigenetic control. 
The results of this study clearly support diandry in N. celidotus and provide insight into the fundamental differences in gonad morphology. Also, the results warrant further investigation into male developmental pathways and the role of epigenetic regulation. These findings provide critical knowledge towards developing the spotty as a model species for sex change research in temperate species.

text: Gonad examination reveals diandry and baseline DNA methylation in the three sexual phenotypes of the New Zealand spotty wrasse, Notolabrus celidotus Understanding reproductive plasticity and how sexual phenotypes arise is of great interest to biology, particularly the form and function of sex changing fish. However, there are gaps regarding detailed descriptions of gonad morphology and structure of the different sexual phenotypes. Furthermore, the role of epigenetic regulation has yet to be applied to these studies. 
Sexually mature terminal phase (TP) males were significantly larger in length, and weight (214 ± 7.74 mm standard length (SL), 146 ± 16.6 g), than the similar sized sexually mature initial phase (IP) males (169 ± 6.24 mm SL, 67 ± 9.52 g) and sexually mature females (167 ± 3.54 mm SL, 61 ± 4.07 g). There was a large overlap in size distributions with a vast size range in sexually mature males (147 – 240 mm SL, 42 – 221 g) and small sexually mature females (146 – 183 mm, 41 – 82 g). These results suggest small males use female mimicry and overlapping size ranges suggest diandry. 
Three gonad types were identified, one ovary and two types of testis. Solid testes were more common in IP males than in TP males. It is proposed that the unique and complex shape of the solid testis arises through an evagination process in juvenile males. Hollow testes arise through sex change from female and are more common in TP males. Colour phase not always corresponding to testis type suggests the ability to transition between body colour phenotype according to environmental influences, and two testis types suggest two different developmental pathways to become a male (diandry). 
Females and one male were identified as juveniles. All sexually mature males had similar testis lobular structure and somatic and germ cell arrangement. The structural arrangement of the solid testis was consistent with primary male testes, and the hollow testis was consistent with secondary male testes. Juvenile males and the existence of primary and secondary testes are associated with diandry in protogynous species. 
Whole-genome percentage methylation analysis revealed no significant difference in global brain DNA methylation between females (71.4 ± 1.06 %), TP males (72.2 ± 0.5 %) or IP males (75.1 %). Global ovarian methylation (53.7 ± 1.16 %) was significantly lower than both the similarly high global methylation in the IP male testis (82.2 ± 1.39 %) and TP male testis (86.8 ± 0.21 %). Ovaries during spawning season (67.3 ± 1.27 %) had significantly higher global methylation than ovaries outside of spawning season (51.4 ± 0.96 %). Global gonad DNA methylation variations suggest sex-specific differences and seasonal effects on reproduction are under epigenetic control. 
The results of this study clearly support diandry in N. celidotus and provide insight into the fundamental differences in gonad morphology. Also, the results warrant further investigation into male developmental pathways and the role of epigenetic regulation. These findings provide critical knowledge towards developing the spotty as a model species for sex change research in temperate species.

year: 2020

title: The synthesis of water-soluble analogues of Pt₂(μ₂-S)₂(PPh₃)₄

authors: Sutton, Ryan

subjects: Chemistry

abstract: Platinum has a very rich chemistry with sulfur, and this field has been extensively studied. Of particular interest are complexes containing the {Pt₂(μ₂-S)₂} core, comprising two platinum atoms with μ₂-sulfurs bridging through a flexible hinge. These complexes can act as potent metalloligands (through the two sulfurs) toward a wide range of transition metal and other centres, allowing for the synthesis of complexes with trinuclear mixed-metal cores {Pt₂(μ₃-S)₂M} (M = heterometal). The {Pt₂(μ₂-S)₂} core is also highly nucleophilic and alkylated by the mildest of reagents. The ancillary ligands coordinated to the {Pt₂(μ₂-S)₂} core are primarily triphenylphosphine (PPh₃), resulting in the complexes being significantly insoluble in water, preventing any forms of bioactivity or biphasic catalysis from being assessed.
This research project has widened the scope of {Pt₂(μ₂-S)₂} complexes via the synthesis of the new water-soluble complexes {Pt₂(μ₂-S)₂}(PTA)₄, [Pt₂(μ₃- S)₂(PTA)₄Rh(cod)]Cl, and [Pt₃(μ3-S)₂(PTA)6]²⁺ (PTA = 1,3,5-triaza-7- phosphaadamantane, cod = 1,5-cyclooctadiene) that were characterised by electrospray ionisation mass spectrometry (ESI-MS) and phosphorus-31 nuclear magnetic resonance spectroscopy (³¹P{¹H} NMR). The complex [Pt₃(μ₃- S)₂(PTA)₆]²⁺ was synthesised during the research into the use of a sulfide exchange column as an alternative source of sulfide for the synthesis of Pt₂(μ₂- S)₂(PTA)₄.
The water-soluble phosphine ligands tris(2-carboxyethyl)phosphine (TCEP) and monosulfonated triphenylphosphine [TPPMS]⁻ were determined to be unsuitable ligands for complexes of the general form {Pt₂(μ₂-S)₂}(L)₄ (L = TCEP, [TPPMS]⁻). During these attempted syntheses the complex {Pt₂(μ₂-S)₂} (cod)₂ was successfully produced and characterised with ESI-MS, ¹H NMR, ¹H-¹H COSY, and ¹³C-¹H HSQC (Proton nuclear magnetic resonance spectroscopy, Correlation Spectroscopy, Heteronuclear Single Quantum Coherence).
The use of thioacetamide (CH₂C(S)NH₂) as an alternative source of sulfide in the synthesis of {Pt₂(μ₂-S)₂}(PPh₃)₄ was found to be a poor substitute for the well established Na₂S·9H₂O. The reaction does result in [Pt(CH₃C(S)NH)(PPh₃)₂]⁺+, subsequently isolated as the BPh₄- salt, [Pt(CH₃C(S)NH)(PPh₃)₂](BPh₄) and was characterised by ESI-MS and ³¹P{1H} NMR. The X-ray crystal structure of the by-product trans-Pt(SC(O)CH₃)₂(PPh₃)₂ was obtained.

text: The synthesis of water-soluble analogues of Pt₂(μ₂-S)₂(PPh₃)₄ Platinum has a very rich chemistry with sulfur, and this field has been extensively studied. Of particular interest are complexes containing the {Pt₂(μ₂-S)₂} core, comprising two platinum atoms with μ₂-sulfurs bridging through a flexible hinge. These complexes can act as potent metalloligands (through the two sulfurs) toward a wide range of transition metal and other centres, allowing for the synthesis of complexes with trinuclear mixed-metal cores {Pt₂(μ₃-S)₂M} (M = heterometal). The {Pt₂(μ₂-S)₂} core is also highly nucleophilic and alkylated by the mildest of reagents. The ancillary ligands coordinated to the {Pt₂(μ₂-S)₂} core are primarily triphenylphosphine (PPh₃), resulting in the complexes being significantly insoluble in water, preventing any forms of bioactivity or biphasic catalysis from being assessed.
This research project has widened the scope of {Pt₂(μ₂-S)₂} complexes via the synthesis of the new water-soluble complexes {Pt₂(μ₂-S)₂}(PTA)₄, [Pt₂(μ₃- S)₂(PTA)₄Rh(cod)]Cl, and [Pt₃(μ3-S)₂(PTA)6]²⁺ (PTA = 1,3,5-triaza-7- phosphaadamantane, cod = 1,5-cyclooctadiene) that were characterised by electrospray ionisation mass spectrometry (ESI-MS) and phosphorus-31 nuclear magnetic resonance spectroscopy (³¹P{¹H} NMR). The complex [Pt₃(μ₃- S)₂(PTA)₆]²⁺ was synthesised during the research into the use of a sulfide exchange column as an alternative source of sulfide for the synthesis of Pt₂(μ₂- S)₂(PTA)₄.
The water-soluble phosphine ligands tris(2-carboxyethyl)phosphine (TCEP) and monosulfonated triphenylphosphine [TPPMS]⁻ were determined to be unsuitable ligands for complexes of the general form {Pt₂(μ₂-S)₂}(L)₄ (L = TCEP, [TPPMS]⁻). During these attempted syntheses the complex {Pt₂(μ₂-S)₂} (cod)₂ was successfully produced and characterised with ESI-MS, ¹H NMR, ¹H-¹H COSY, and ¹³C-¹H HSQC (Proton nuclear magnetic resonance spectroscopy, Correlation Spectroscopy, Heteronuclear Single Quantum Coherence).
The use of thioacetamide (CH₂C(S)NH₂) as an alternative source of sulfide in the synthesis of {Pt₂(μ₂-S)₂}(PPh₃)₄ was found to be a poor substitute for the well established Na₂S·9H₂O. The reaction does result in [Pt(CH₃C(S)NH)(PPh₃)₂]⁺+, subsequently isolated as the BPh₄- salt, [Pt(CH₃C(S)NH)(PPh₃)₂](BPh₄) and was characterised by ESI-MS and ³¹P{1H} NMR. The X-ray crystal structure of the by-product trans-Pt(SC(O)CH₃)₂(PPh₃)₂ was obtained.

year: 2019

title: The biology and general ecology of the Koaro (Galaxias brevipinnis) in some tributary streams of Lake Taupo

authors: Kusabs, Ian Andrew

abstract: The ecology and general biology of Galaxias brevipinnis were studied in three tributary streams of Lake Taupo between May 1988 and April 1989. Adult koaro were found in relatively high densities in the Waipehi and Omori streams but in low densities in the larger Waiotaka stream. The results of population estimation studies suggest that the distribution and abundance of koaro is negatively correlated with that of trout. There was a general decline in the population density of stream-resident koaro in the winter months. Juvenile koaro were found to migrate into the tributaries from August to December, with migrations being at a peak in October and November.

Population length-frequency distributions and otoliths used to age koaro indicated that there were up to 5 age classes. Growth was allometric and was adequately described by the von Bertalanffy equation after the first year of life. Koaro were found to be in best condition in the Spring and lowest in Winter.

Spawning appeared to occur from December through to April peaking in late Summer to early in the Waipehi Stream was Autumn. The mean fecundity of koaro approximately 5500. A sex-ratio of approximately 1:1 (males: females) were found in the koaro populations in the Omori and Waipehi streams, but during spawning there were always more ripe males than gravid females.

There was considerable overlap in the diets of both koaro and juvenile rainbow trout in the Waipehi and Omori streams, with invertebrates being consumed according to their relative abundance in the benthos. Ephemeroptera larvae were numerically the most important food item in the diet of both species. However, by weight, fish (juvenile koaro) were the most important food · item in the diet of koaro and rainbow trout in the Waipehi stream. In the Omori stream in Winter, trout eggs were the most important food item in terms of weight. Terrestrial prey was found to be of relatively minor importance in the diets of koaro and rainbow trout in the Waipehi and Omori streams.

text: The biology and general ecology of the Koaro (Galaxias brevipinnis) in some tributary streams of Lake Taupo The ecology and general biology of Galaxias brevipinnis were studied in three tributary streams of Lake Taupo between May 1988 and April 1989. Adult koaro were found in relatively high densities in the Waipehi and Omori streams but in low densities in the larger Waiotaka stream. The results of population estimation studies suggest that the distribution and abundance of koaro is negatively correlated with that of trout. There was a general decline in the population density of stream-resident koaro in the winter months. Juvenile koaro were found to migrate into the tributaries from August to December, with migrations being at a peak in October and November.

Population length-frequency distributions and otoliths used to age koaro indicated that there were up to 5 age classes. Growth was allometric and was adequately described by the von Bertalanffy equation after the first year of life. Koaro were found to be in best condition in the Spring and lowest in Winter.

Spawning appeared to occur from December through to April peaking in late Summer to early in the Waipehi Stream was Autumn. The mean fecundity of koaro approximately 5500. A sex-ratio of approximately 1:1 (males: females) were found in the koaro populations in the Omori and Waipehi streams, but during spawning there were always more ripe males than gravid females.

There was considerable overlap in the diets of both koaro and juvenile rainbow trout in the Waipehi and Omori streams, with invertebrates being consumed according to their relative abundance in the benthos. Ephemeroptera larvae were numerically the most important food item in the diet of both species. However, by weight, fish (juvenile koaro) were the most important food · item in the diet of koaro and rainbow trout in the Waipehi stream. In the Omori stream in Winter, trout eggs were the most important food item in terms of weight. Terrestrial prey was found to be of relatively minor importance in the diets of koaro and rainbow trout in the Waipehi and Omori streams.

year: 1989