In situ changes of tropical crustose coralline algae along carbon dioxide gradients.

Crustose coralline algae (CCA) fulfill important ecosystem functions in coral reefs, including reef framework stabilization and induction of larval settlement. To investigate in situ the effects of high carbon dioxide on CCA communities, we deployed settlement tiles at three tropical volcanic CO2 seeps in Papua New Guinea along gradients spanning from 8.1 to 7.4 pH. After 5 and 13 months deployment, there was a steep transition from CCA presence to absence around pH 7.8 (660 µatm pCO2): 98% of tiles had CCA at pH > 7.8, whereas only 20% of tiles had CCA at pH ≤ 7.8. As pH declined from 8.0 to 7.8, the least and most sensitive CCA species lost 43% and 85% of cover, respectively. Communities on upward facing surfaces exposed to high light and high grazing pressure showed less steep losses than those on shaded surfaces with low grazing. Direct CO2 effects on early life stages were the main mechanisms determining CCA cover, rather than competitive interactions with other benthic groups. Importantly, declines were steepest at near-ambient pH, suggesting that CCA may have already declined in abundance due to the recent seawater pH decline of 0.1 units, and that future severe losses are likely with increasing ocean acidification.

Ecological effects of ocean acidification and habitat complexity on reef-associated macroinvertebrate communities.

The ecological effects of ocean acidification (OA) from rising atmospheric carbon dioxide (CO2) on benthic marine communities are largely unknown. We investigated in situ the consequences of long-term exposure to high CO2 on coral-reef-associated macroinvertebrate communities around three shallow volcanic CO2 seeps in Papua New Guinea. The densities of many groups and the number of taxa (classes and phyla) of macroinvertebrates were significantly reduced at elevated CO2 (425-1100 µatm) compared with control sites. However, sensitivities of some groups, including decapod crustaceans, ascidians and several echinoderms, contrasted with predictions of their physiological CO2 tolerances derived from laboratory experiments. High CO2 reduced the availability of structurally complex corals that are essential refugia for many reef-associated macroinvertebrates. This loss of habitat complexity was also associated with losses in many macroinvertebrate groups, especially predation-prone mobile taxa, including crustaceans and crinoids. The transition from living to dead coral as substratum and habitat further altered macroinvertebrate communities, with far more taxa losing than gaining in numbers. Our study shows that indirect ecological effects of OA (reduced habitat complexity) will complement its direct physiological effects and together with the loss of coral cover through climate change will severely affect macroinvertebrate communities in coral reefs.

PHOTOSYNTHETIC SYMBIONTS AND ENERGY SUPPLY DETERMINE OCTOCORAL BIODIVERSITY IN CORAL REEFS.

Many coral reef organisms live in symbiotic relationships with photosynthetic microalgae. This symbiosis extends the energy resources available to reef organisms, thereby potentially influencing biodiversity. In octocorals, about one-half of the taxa contain photosynthetic symbionts while the rest do not, and thus octocorals are an ideal model to assess the relationships between biodiversity, spatial and environmental factors, and photosynthetic symbionts. Data collected from 1106 sites on the Great Barrier Reef, Australia, between 12° and 24° S showed that taxa with photosynthetic symbionts (phototrophs) had higher abundances, wider ranges, and a wider spread of locations than taxa without symbionts (heterotrophs). In phototrophic assemblages, spatial turnover comprised both exchange and loss of taxa, and their richness was high across a broad range of environmental conditions. In contrast, heterotrophs were uncommon, had short ranges, and were located where energy supply was highest and disturbance lowest. Turnover between heterotrophic assemblages comprised taxonomic loss rather than exchange of taxa. The biodiversity patterns and differences between phototrophic and heterotrophic octocorals are similar to those recorded in more spatially limited studies of phototrophic sponges and hard corals, and heterotrophic sponges. This study therefore suggests that the association, or not, with photosynthetic symbionts, and spatial and environmental factors related to energy supply and disturbance are principal drivers of biodiversity, community composition, and ranges of coral reef benthos.

Effects of short-term treatment with progesterone superimposed on 11 or 17 days of norgestomet treatment on the interval to oestrus and fertility in Bos indicus heifers.

The aims of this study were to determine: (1) if short-term treatment of Bos indicus heifers with progesterone (P4) while implanted with a s.c. norgestomet implant for 17 days would influence the time interval to oestrus and increase fertility of the synchronised oestrus, and (2) whether the response to treatment with P4 would differ between heifers treated with a norgestomet implant for 17 vs. 11 days when short-term treatment with P4 is applied 3 days prior to implant removal. B. indicus heifers at two separate sites (A and B) were allocated to three groups at each site. Heifers in two groups (NG and NGP4 groups) were given a single s.c. norgestomet implant on the first day of treatment (day 0) while heifers in a third group (NGP4PG group) were implanted on day 6. A single P4 releasing Controlled Internal Drug Release device (CIDR) was inserted on day 14 in heifers in the NGP4 and NGP4PG groups and was removed 23.5 +/- 0.07 h later (day 15). Heifers in the NGP4PG group were administered an analogue of prostaglandin F2 alpha (PGF2 alpha) at the time of CIDR removal to regress corpora lutea. Implants were removed from all heifers on the same day (day 17) and a 400 IU of equine chorionic gonadotrophin (ECG) was administered s.c. Animals were artificially inseminated 11.1 +/- 0.17 h after detection of oestrus, using frozen semen from one bull at site A and one of five bulls at site B. Inseminations were carried out by one of two technicians. Treatment with P4 delayed oestrus and reduced the synchrony of oestrus at site A (hours to oestrus +/- SD: NG group, 39.0 +/- 13.7; NGP4 group, 66.3 +/- 24.4; NGP4PG group, 58.9 +/- 20.5 h; P < 0.05) but not at site B (41.4 +/- 15.2, 42.5 +/- 10.1, 45.4 +/- 10.3 h; P > 0.05). Pregnancy rates 6 weeks after insemination were found to be significantly associated with bull (P < 0.001), treatment group (P = 0.013) and insemination technician (P = 0.033). Pregnancy rates were greater in the heifers in the NGP4 group than heifers in the NG group [50.3% (78/155) vs. 36.4% (60/165); odds ratio = 1.83, 95% CI = 1.14 to 2.96] and similar between heifers in the NGP4 and NGP4PG groups [50.3% (78/155) vs. 51.1% (63/117); odds ratio = 1.06, 95% CI = 0.67 to 1.69]. It was concluded that acute treatment with P4 can improve pregnancy rates in B. indicus heifers treated for 17 days with norgestomet implants. Reducing the duration of norgestomet treatment to 11 days and administration of PGF2 alpha at the time of ending treatment with a CIDR device resulted in no differences in fertility, mean intervals to oestrus or synchrony of oestrus.

Granulosa cell apoptosis, aromatase activity, cyclic adenosine 3',5'-monophosphate response to gonadotropins, and follicular fluid steroid levels during spontaneous and induced follicular atresia in ewes.

The aims of the present study in ewes were 1) to test the hypothesis that apoptosis in granulosa cells is one of the processes involved in the structural demise of follicles and 2) to define the temporal relationships among the occurrence and degree of apoptosis in granulosa cells, aromatase activity, production of cyclic AMP (cAMP) by granulosa cells in response to FSH or LH, concentrations of estradiol 17 beta (E2) and progesterone in follicular fluid, and the characteristic morphometric changes associated with the process of follicular atresia. To address these aims, ewes were treated with either saline or steroid-free bovine follicular fluid (bFF) at 60 h after estrus, and ovarian follicles > or = 3 mm diameter were recovered at 0, 12, 18, or 24 h later. Apoptotic granulosa cells were identified by the presence of oligonucleosomes after 3'-end labeling of extracted DNA with [32P]alpha dideoxy ATP (ddATP). The degree of oligonucleosome formation, based on the intensity of radiolabeling, was given an apoptosis score (AP) of 0 (nondetectable), 1 (slight), 2 (moderate), or 3 (marked). Moreover, a labeling index (LI) was calculated from the amount of radiolabeled ddATP incorporated into low-molecular weight (< 4.2 kb) DNA fragments. On the basis of morphometric criteria, 73% (141 of 194) of the follicles classified as healthy had apoptotic granulosa cells compared to 86% (18 of 21) of the follicles classified as atretic. In the bFF-but not saline-treated ewes, the concentrations of plasma FSH had declined to basal values at 12 h after treatment. At the beginning of the treatment period, the degree of granulosa cell apoptosis was either undetectable (AP = 0, 47% of follicles) or slight (AP = 1, 44% of follicles) in the majority of follicles. After 12 h from the bFF but not the saline injection, there was a significant increase in the proportion of follicles (> or = 3 mm diameter) per ewe containing apoptotic granulosa cells (p < 0.001) and a significant decrease in the number of follicles per ewe with aromatase activity (p < 0.05) and with follicular fluid E2 > 20 ng/ml (p < 0.05). By 24 h after bFF treatment, apoptosis was evident in all follicles (> or = 3 mm diameter), fewer follicles contained FSH-responsive granulosa cells in terms of cAMP production (p < 0.05), and none were LH-responsive. A significant negative relationship was found between the degree of granulosa cell death as measured by L1 and follicular fluid E2 concentrations. In summary, the presence of apoptotic granulosa cells in an appreciable number of follicles considered to be healthy by morphometric criteria and before their commitment to preovulatory enlargement and ovulation suggests that apoptosis may be a physiological process in developing follicles and/or a very early event in atresia. Collectively, these data provide strong evidence that granulosa cells may die by apoptosis before there is an appreciable decrease in the capacity of the granulosa cell layer as a whole to respond to gonadotropins or to produce E2.

Effect of 48 h treatment with 17 beta-oestradiol or progesterone on follicular wave emergence and synchrony of ovulation in Bos indicus cows when administered at the end of a period of progesterone treatment.

The objective of this study was to determine the effect of treatment with additional progesterone (P4) or 17 beta-oestradiol (E2) at the end of a period of P4 treatment on ovarian follicular development, ovulation time, and plasma gonadotrophin and steroid hormone concentrations of Bos indicus cows. Initially, two injections of PGF2 alpha were given 14 days apart, and at the time of the second injection (Day 0) all cows received a single P4-releasing controlled internal drug release (CIDR) device that was removed 10 days later. Control cows (Group 1, n = 8) received no other treatment. On Day 8, cows in Group 2 (n = 8) and Group 3 (n = 8) received either a s.c. implant containing E2, or a second CIDR device, respectively. All CIDR devices and E2 implants were removed at a similar time on Day 10. Treatment with E2 or P4 delayed mean (+/- SD) time of ovulation (113.1 +/- 25.6 h, 153.4 +/- 44.5 h and 150.8 +/- 25.1 h for Groups 1, 2 and 3, respectively; P < 0.05) and the mean time (+/- SD) of the luteinising hormone (LH) peak (87.4 +/- 24.5 h, 124.3 +/- 45.0 h and 122.3 +/- 25.04 h for Groups 1, 2 and 3, respectively; P < 0.05). Both treatments delayed the mean (+/- SD) day of emergence of the ovulatory follicle (7.7 +/- 3.6 days, 11.3 +/- 1.7 days and 11.1 +/- 1.5 days for Groups 1, 2 and 3, respectively; P < 0.05), and reduced the variability in the day of emergence of the ovulatory follicle (P < 0.05) compared with the control cows. Variability in age and duration of dominance of the ovulatory follicle was greater in control animals compared with treated animals (P < 0.05). Treatment with E2 on Days 9 and 10 did not alter mean concentrations of gonadotrophins in the cows in Group 2 compared with control cows (P > 0.05), whereas treatment of cows with an additional CIDR device resulted in greater mean concentrations of FSH and lesser concentrations of LH on Day 9 (P < 0.05) compared with cows in Groups 1 and 2. By Day 10 mean concentrations of gonadotrophins were similar among cows in all three groups. Concentrations of E2 were less in cows in Group 3 compared with cows in Groups 1 and 2 from Day 9 to Day 11 (P < 0.05). We conclude that treatment with either E2 or P4 can influence the pattern of ovarian follicular development and ovulation in cattle; however, the mechanism of action of the two treatments may differ. Atretogenic treatments for ovarian follicles applied at the end of a period of progesterone treatment did not improve synchrony of ovulation.

Sequential changes in ovarian follicular dynamics in Bos indicus heifers before and after nutritional anoestrus.

This study examined the effects of live mass on ovarian follicular dynamics in heifers before and after the onset of nutritional anoestrus. The effects of decreased live mass on secretion of progesterone, LH and FSH were also investigated. Ovarian characteristics were monitored in 16 postpubertal Brahman heifers using daily transrectal ultrasonography. After two normal oestrous cycles, 11 heifers (treatment group) were allocated to a restricted diet, until the cessation of their oestrous cycles, that resulted in a decrease in live mass of 0.8 kg day-1. Heifers were then fed an ad libitum diet, resulting in increasing live mass until resumption of oestrous cycles. Five heifers (control group) were fed an unrestricted diet throughout the experimental period. The concentrations of progesterone in plasma were monitored twice a week and the concentrations of LH and FSH were determined on day 6 after ovulation, before initiation of dietary restriction, after a 17% decrease in live mass and after the onset of anoestrus in the treatment group. Onset of anoestrus was preceded by linear decreases in the size of ovarian follicles and corpora lutea, and in the persistence of the first dominant follicles of oestrous cycles. These changes were proportional to the decrease in live mass (P < 0.001). The frequency of pulses of LH or mean concentration of FSH on day 6 of the oestrous cycle were not changed after a 17% decrease in live mass, and did not increase following the onset of anoestrus, although concentrations of progesterone were < 0.2 ng ml-1, suggesting that release of LH was suppressed at this time.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoglobulin containing cells in normal and inflamed accessory sex glands of bulls.

The peroxidase-antiperoxidase (PAP) technique was used to identify cytoplasmic immunoglobulins in the accessory sex glands of 15 normal bulls and 13 bulls with inflammation of the ASG. Immunoglobulin containing cells (ICC) of the types IgA, IgM, total IgG, IgG1 and IgG2 were measured and their percentages expressed. In accessory sex glands from normal bulls, IgA containing cells were the most frequent in prostate and bulbourethral glands (86.7% and 86.1%, respectively of all ICC present) whereas in the ampulla, IgG containing cells comprised 78.6% of the ICC. IgG1 and IgG2 containing cells were present in all the accessory sex glands in approximately equal numbers. Frequencies of IgM containing cells in the ampulla, prostate and bulbourethral glands were 6.3%, 4.0% and 3.7%, respectively. Although all isotypes of ICC were present in the seminal vesicle, the very low number precluded accurate quantification. In inflamed ampulla, seminal vesicle, bulbourethral gland and colliculus seminalis, IgG containing cells were the most frequent ICC with values of 66.2%, 83.0%, 69.0% and 53.5%, respectively; IgA containing cells were the second in prevalence with values of 21.5%, 10.3% 19.3% and 40.5%, respectively. The contribution of ICC to the locally protective immunoglobulins in accessory sex gland secretions is discussed.

THE SPREAD OF MYCORRHIZAL INFECTION BY GIGASPORA CALOSPORA FROM A LOCALIZED INOCULUM.

The lateral spread of Gigaspora calospora (Nicol. and Gerd.) Gerdemann & Trappe was examined in Trifolium subterraneum L. (subterranean clover) grown on a steamed lateritic podsol. Plants were sown in a sward in pots 29 cm long × 12 cm wide and inoculum of G. calospora was placed at one end. Mycorrhizal infection was estimated 21, 35, 63, 91 and 119 d after sowing at points 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24 and 26 cm from the inoculum. The lateral spread of Glotnusfasciculatum (Thaxter sensu Gerd.) through roots of T. subterraneum was measured 35 d after sowing. The percentage root length infected by G. calospora declined exponentially with distance from the inoculum. In contrast, infection by G. fasciculatum spread with a distinct front and hence was best described by a Gompertz curve. The number of spores of G. calospora recovered at increasing distances from the point of inoculation at the final harvest was correlated with the proportion of roots infected at an earlier harvest, and therefore provided a useful measure of the pattern of spread of G. calospora within roots.