Timeless or tainted? The effects of male ageing on seminal fluid

Reproductive ageing can occur due to the deterioration of both the soma and germline. In males, it has mostly been studied with respect to age-related changes in sperm. However, the somatic component of the ejaculate, seminal fluid, is also essential for maintaining reproductive function. Whilst we know that seminal fluid proteins (SFPs) are required for male reproductive success across diverse taxa, age-related changes in SFP quantity and composition are little understood. Additionally, only few studies have explored the reproductive ageing of the tissues that produce SFPs, and the resulting reproductive outcomes. Here we provide a systematic review of studies addressing how advancing male age affects the production and properties of seminal fluid, in particular SFPs and oxidative stress, highlighting many open questions and generating new hypotheses for further research. We additionally discuss how declines in function of different components of seminal fluid, such as SFPs and antioxidants, could contribute to age-related loss of reproductive ability. Overall, we find evidence that ageing results in increased oxidative stress in seminal fluid and a decrease in the abundance of various SFPs. These results suggest that seminal fluid contributes towards important age-related changes influencing male reproduction. Thus, it is essential to study this mostly ignored component of the ejaculate to understand male reproductive ageing, and its consequences for sexual selection and paternal age effects on offspring.

Functional insights from the GC-poor genomes of two aphid parasitoids, Aphidius ervi and Lysiphlebus fabarum

BACKGROUND

Parasitoid wasps have fascinating life cycles and play an important role in trophic networks, yet little is known about their genome content and function. Parasitoids that infect aphids are an important group with the potential for biological control. Their success depends on adapting to develop inside aphids and overcoming both host aphid defenses and their protective endosymbionts.

RESULTS

We present the de novo genome assemblies, detailed annotation, and comparative analysis of two closely related parasitoid wasps that target pest aphids: Aphidius ervi and Lysiphlebus fabarum (Hymenoptera: Braconidae: Aphidiinae). The genomes are small (139 and 141 Mbp) and the most AT-rich reported thus far for any arthropod (GC content: 25.8 and 23.8%). This nucleotide bias is accompanied by skewed codon usage and is stronger in genes with adult-biased expression. AT-richness may be the consequence of reduced genome size, a near absence of DNA methylation, and energy efficiency. We identify missing desaturase genes, whose absence may underlie mimicry in the cuticular hydrocarbon profile of L. fabarum. We highlight key gene groups including those underlying venom composition, chemosensory perception, and sex determination, as well as potential losses in immune pathway genes.

CONCLUSIONS

These findings are of fundamental interest for insect evolution and biological control applications. They provide a strong foundation for further functional studies into coevolution between parasitoids and their hosts. Both genomes are available at https://bipaa.genouest.org.

Physiological Maturation Lags Behind Behavioral Maturation in Newly Eclosed Drosophila melanogaster Males

The accessory gland (AG) produces seminal fluid proteins that are transferred to the female upon mating in many insects. These seminal fluid proteins often promote a male's post-copulatory reproductive success. Despite its crucial function many males eclose with a small gland not yet containing the full set of proteins. Thus, they need a physiological maturation period. Using Drosophila melanogaster, we tested whether this physiological maturation is linked to behavioral maturation in males and to what extent seminal fluid allocation patterns are influenced by physiological maturation. To that end, we measured AG protein content (as a proxy for physiological maturation) of young, immature males that were either successful in gaining a mating, but prevented from transferring seminal fluid proteins, or unsuccessful, thus using mating success as a proxy for behavioral maturation. Furthermore, we compared ejaculate allocation in immature and mature males in a single mating. Though mating success and gland maturation increase with male age, we found no evidence for a fine-tuned synchronization of behavioral and physiological maturation in males. This is especially surprising since we found reduced ejaculate allocation in very young, immature males, hinting at reduced fitness benefits from early matings in D. melanogaster.

Leptospirosis in Israel: a report of 14 cases caused by icterohaemorrhagiae serogroup (1968-82)

Fourteen cases of leptospirosis due to the Leptospira interrogans serogroup Icterohaemorrhagiae (Weil's disease) were serologically confirmed in the last 15 years. In two cases, Icterohaemorrhagiae was also isolated from the patients' blood. Both positive cultures were obtained in Korthof's medium by indirect passage through brain-heart infusion medium. One of the isolates was identified as serovar budapest, which has never been reported in Israel. In most of the cases, paradoxical cross-reactions with serovars of the Autumnalis, Hebdomadis and Canicola serogroups were observed in the early stages of the illness. In all cases, we suspected that the source of the infection was serovars of the Icterohaemorrhagiae serogroup shed in the urine of Rattus norvegicus rats. Thirteen of the affected persons were working and living in the Tel Aviv area, all in places not known to be Icterohaemorrhagiae endemic before 1968. One patient was working and living in the Hadera region. All patients were jaundiced, and one died. The illness was usually accompanied by pronounced and long-lasting elevation of blood bilirubin and urea levels.

Leptospirosis in Israel: epidemiological features and laboratory findings in 13 human cases due to Leptospira ballum

Thirteen sporadic cases of human leptospirosis due to Leptospira ballum were laboratory confirmed during a period of 11 yr. In four cases the diagnosis was proved retrospectively. All but three were residents of the Sharon plain region, living 10 to 15 km apart. All were engaged in some form of agriculture, especially in irrigated fields or groves, or in chicken farming. It was suspected that wet soil contaminated with the urine of rodents, carriers of L. ballum, was the main source of infection. Two types of immunological response were observed: 1) high microscopic agglutination (MA) titers with L. ballum serovar only (nine cases); and 2) considerable coagglutination titers with heterologous serovars as well (four cases). The serological follow-up of these cases for several years revealed that in some, a relatively high MA titer (1:200 to 1:400) against L. ballum serovars persisted for 4 to 9 yr. Sera from 10 patients were tested for IgM and IgG anti-bodies by the MA test. In eight cases the IgM responded to a higher titer and persisted for many years, regardless of whether or not any IgG agglutinins were detected. The importance of blood cultures is emphasized and the possibility of misinterpretation of MA results is discussed.

Leptospirosis in man, Israel, 1970-1979

In 1970-1979, the incidence of human leptospirosis in Israel was 0.7 per 100,000 population. The majority of the cases (62%) occurred in northeastern Israel (Upper Galilee). Prior to 1973 the main infecting serotypes were grippotyphosa (41%) and Hebdomadis szwajizak (31%). Following the first outbreak of Hebdomadis hardjo infection in 1973, a change occurred in the epidemiologic pattern of human leptospirosis, with hardjo becoming the most common serotype (59%). Hardjo infection outbreaks were sporadic and localized to dairy farms. The peak of incidence was during the summer months, June-September. All the patients with hardjo were dairy workers. The illness was relatively mild and mostly unicteric. Cattle seemed to be the principal source of hardjo infection for man.

Leptospirosis in Rattus norvegicus and Rattus rattus in Israel

Leptospires were isolated from 21.2% of Rattus norvegicus (the brown rat) and 9.9% of Rattus rattus trapped in a survey of urban and rural areas in Israel. Microagglutination antibodies were found in sera of 9.4 and 8.1% of these rats, respectively. The 191 strains isolated belonged to six serogroups: Leptospira icterohaemorrhagiae (169), L. bataviae (3), L. semeranga (1), L andamana (1) and L. ballum (1) from R. norvegicus and L. ballum (13) and L. hebdomadis (3) from R. rattus. No significant differences were found between the infection rate of mature male and female brown rats, but all six strains isolated from young animals were obtained from male rats. Two factors influence the rat of Leptospira infection among urban brown rats: the age of the animals and the area in which they are trapped. Adult brown rats trapped in a newly infected area showed a considerably higher level of contamination (61.8%) than those trapped in areas where the infection had persisted for many years (22.8%). Young rats showed a low degree of contamination in both the old foci (5.7%) and the new foci (2.2%). New and highly infected areas were found during this survey in Tel Aviv (Carmel market) and its neighboring cities of Holon, Ramat Gan and Givatayim.

Isolation of a 'saprophytic' leptospiral serotype andamana from carrier rats in Israel

The first isolation of two leptospira strains belonging to the serotype andamana from the kidney of Rattus norvegicus is reported. A strain of this serotype has never before been isolated in the Middle East, nor from any rodent in any other part of the world. Its epidemiologic significance and the classification of this serotype as part of the saprophytic Biflexa species is discussed.